diff --git a/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigManager.kt b/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigManager.kt
index 4f67ea3a..af24ea7c 100644
--- a/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigManager.kt
+++ b/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigManager.kt
@@ -10,10 +10,11 @@ package xyz.nulldev.ts.config
 import ch.qos.logback.classic.Level
 import com.typesafe.config.Config
 import com.typesafe.config.ConfigFactory
+import com.typesafe.config.ConfigObject
 import com.typesafe.config.ConfigValue
-import com.typesafe.config.ConfigValueFactory
 import com.typesafe.config.parser.ConfigDocument
 import com.typesafe.config.parser.ConfigDocumentFactory
+import io.github.config4k.toConfig
 import io.github.oshai.kotlinlogging.KotlinLogging
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
@@ -113,7 +114,7 @@ open class ConfigManager {
     ) {
         mutex.withLock {
             val actualValue = if (value is Enum<*>) value.name else value
-            val configValue = ConfigValueFactory.fromAnyRef(actualValue)
+            val configValue = actualValue.toConfig("internal").getValue("internal")
 
             updateUserConfigFile(path, configValue)
             internalConfig = internalConfig.withValue(path, configValue)
@@ -142,8 +143,13 @@ open class ConfigManager {
         val serverConfig = ConfigFactory.parseResources("server-reference.conf")
         val userConfig = getUserConfig()
 
-        val hasMissingSettings = serverConfig.entrySet().any { !userConfig.hasPath(it.key) }
-        val hasOutdatedSettings = userConfig.entrySet().any { !serverConfig.hasPath(it.key) }
+        // NOTE: if more than 1 dot is included, that's a nested setting, which we need to filter out here
+        val refKeys =
+            serverConfig.root().entries.flatMap {
+                (it.value as? ConfigObject)?.entries?.map { e -> "${it.key}.${e.key}" }.orEmpty()
+            }
+        val hasMissingSettings = refKeys.any { !userConfig.hasPath(it) }
+        val hasOutdatedSettings = userConfig.entrySet().any { !refKeys.contains(it.key) && it.key.count { c -> c == '.' } <= 1 }
         val isUserConfigOutdated = hasMissingSettings || hasOutdatedSettings
         if (!isUserConfigOutdated) {
             return
@@ -159,7 +165,8 @@ open class ConfigManager {
             .filter {
                 serverConfig.hasPath(
                     it.key,
-                )
+                ) ||
+                    it.key.count { c -> c == '.' } > 1
             }.forEach { newUserConfigDoc = newUserConfigDoc.withValue(it.key, it.value) }
 
         newUserConfigDoc =
diff --git a/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigModule.kt b/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigModule.kt
index d569bbf1..aa2b6281 100644
--- a/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigModule.kt
+++ b/AndroidCompat/Config/src/main/java/xyz/nulldev/ts/config/ConfigModule.kt
@@ -8,9 +8,13 @@ package xyz.nulldev.ts.config
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 import com.typesafe.config.Config
+import com.typesafe.config.ConfigException
 import com.typesafe.config.ConfigFactory
-import com.typesafe.config.ConfigValueFactory
+import io.github.config4k.ClassContainer
+import io.github.config4k.TypeReference
 import io.github.config4k.getValue
+import io.github.config4k.readers.SelectReader
+import io.github.config4k.toConfig
 import kotlin.reflect.KProperty
 
 /**
@@ -26,7 +30,7 @@ abstract class ConfigModule(
  */
 abstract class SystemPropertyOverridableConfigModule(
     getConfig: () -> Config,
-    moduleName: String,
+    val moduleName: String,
 ) : ConfigModule(getConfig) {
     val overridableConfig = SystemPropertyOverrideDelegate(getConfig, moduleName)
 }
@@ -46,20 +50,31 @@ class SystemPropertyOverrideDelegate(
         val combined =
             System.getProperty(
                 "$CONFIG_PREFIX.$moduleName.${property.name}",
-                if (T::class.simpleName == "List") {
-                    ConfigValueFactory.fromAnyRef(configValue).render()
-                } else {
-                    configValue.toString()
-                },
+                configValue!!
+                    .toConfig("internal")
+                    .root()
+                    .render()
+                    .removePrefix("internal="),
             )
+        val combinedConfig =
+            try {
+                ConfigFactory.parseString(combined)
+            } catch (_: ConfigException) {
+                ConfigFactory.parseString("internal=$combined")
+            }
 
-        return when (T::class.simpleName) {
-            "Int" -> combined.toInt()
-            "Boolean" -> combined.toBoolean()
-            "Double" -> combined.toDouble()
-            "List" -> ConfigFactory.parseString("internal=" + combined).getStringList("internal").orEmpty()
-            // add more types as needed
-            else -> combined // covers String
-        } as T
+        val genericType = object : TypeReference<T>() {}.genericType()
+        val clazz = ClassContainer(T::class, genericType)
+        val reader = SelectReader.getReader(clazz)
+        val path = property.name
+
+        val result = reader(combinedConfig, "internal")
+        return try {
+            result as T
+        } catch (e: Exception) {
+            throw result
+                ?.let { e }
+                ?: ConfigException.BadPath(path, "take a look at your config")
+        }
     }
 }
diff --git a/AndroidCompat/build.gradle.kts b/AndroidCompat/build.gradle.kts
index e5889b14..cdf20edc 100644
--- a/AndroidCompat/build.gradle.kts
+++ b/AndroidCompat/build.gradle.kts
@@ -47,5 +47,5 @@ dependencies {
 
     // OpenJDK lacks native JPEG encoder and native WEBP decoder
     implementation(libs.bundles.twelvemonkeys)
-    implementation(libs.sejda.webp)
+    implementation(libs.imageio.webp)
 }
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 221dd2dc..fbd28249 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -136,7 +136,7 @@ twelvemonkeys-imageio-metadata = { module = "com.twelvemonkeys.imageio:imageio-m
 twelvemonkeys-imageio-jpeg = { module = "com.twelvemonkeys.imageio:imageio-jpeg", version.ref = "twelvemonkeys" }
 twelvemonkeys-imageio-webp = { module = "com.twelvemonkeys.imageio:imageio-webp", version.ref = "twelvemonkeys" }
 
-sejda-webp = "com.github.usefulness:webp-imageio:0.10.2"
+imageio-webp = "com.github.usefulness:webp-imageio:0.10.2"
 
 # Testing
 mockk = "io.mockk:mockk:1.14.4"
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/ChapterMutation.kt b/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/ChapterMutation.kt
index 5c809293..50824807 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/ChapterMutation.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/ChapterMutation.kt
@@ -16,6 +16,7 @@ import suwayomi.tachidesk.manga.impl.chapter.getChapterDownloadReadyById
 import suwayomi.tachidesk.manga.model.table.ChapterMetaTable
 import suwayomi.tachidesk.manga.model.table.ChapterTable
 import suwayomi.tachidesk.server.JavalinSetup.future
+import java.net.URLEncoder
 import java.time.Instant
 import java.util.concurrent.CompletableFuture
 
@@ -226,7 +227,15 @@ class ChapterMutation {
     data class FetchChapterPagesInput(
         val clientMutationId: String? = null,
         val chapterId: Int,
-    )
+        val format: String? = null,
+    ) {
+        fun toParams(): Map<String, String> =
+            buildMap {
+                if (!format.isNullOrBlank()) {
+                    put("format", format)
+                }
+            }
+    }
 
     data class FetchChapterPagesPayload(
         val clientMutationId: String?,
@@ -236,16 +245,32 @@ class ChapterMutation {
 
     fun fetchChapterPages(input: FetchChapterPagesInput): CompletableFuture<DataFetcherResult<FetchChapterPagesPayload?>> {
         val (clientMutationId, chapterId) = input
+        val paramsMap = input.toParams()
 
         return future {
             asDataFetcherResult {
                 val chapter = getChapterDownloadReadyById(chapterId)
 
+                val params =
+                    buildString {
+                        if (paramsMap.isNotEmpty()) {
+                            append("?")
+                            paramsMap.entries.forEach { entry ->
+                                if (length > 1) {
+                                    append("&")
+                                }
+                                append(entry.key)
+                                append("=")
+                                append(URLEncoder.encode(entry.value, Charsets.UTF_8))
+                            }
+                        }
+                    }
+
                 FetchChapterPagesPayload(
                     clientMutationId = clientMutationId,
                     pages =
                         List(chapter.pageCount) { index ->
-                            "/api/v1/manga/${chapter.mangaId}/chapter/${chapter.index}/page/$index"
+                            "/api/v1/manga/${chapter.mangaId}/chapter/${chapter.index}/page/${index}$params"
                         },
                     chapter = ChapterType(chapter),
                 )
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/SettingsMutation.kt b/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/SettingsMutation.kt
index 7ad5748d..4cc0bc1c 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/SettingsMutation.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/graphql/mutations/SettingsMutation.kt
@@ -111,6 +111,18 @@ class SettingsMutation {
         configSetting.value = newSetting
     }
 
+    private fun <SettingType : Any, RealSettingType : Any> updateSetting(
+        newSetting: RealSettingType?,
+        configSetting: MutableStateFlow<SettingType>,
+        mapper: (RealSettingType) -> SettingType,
+    ) {
+        if (newSetting == null) {
+            return
+        }
+
+        configSetting.value = mapper(newSetting)
+    }
+
     @GraphQLIgnore
     fun updateSettings(settings: Settings) {
         updateSetting(settings.ip, serverConfig.ip)
@@ -140,6 +152,15 @@ class SettingsMutation {
         updateSetting(settings.autoDownloadAheadLimit, serverConfig.autoDownloadNewChaptersLimit) // deprecated
         updateSetting(settings.autoDownloadNewChaptersLimit, serverConfig.autoDownloadNewChaptersLimit)
         updateSetting(settings.autoDownloadIgnoreReUploads, serverConfig.autoDownloadIgnoreReUploads)
+        updateSetting(settings.downloadConversions, serverConfig.downloadConversions) { list ->
+            list.associate {
+                it.mimeType to
+                    ServerConfig.DownloadConversion(
+                        target = it.target,
+                        compressionLevel = it.compressionLevel,
+                    )
+            }
+        }
 
         // extension
         updateSetting(settings.extensionRepos, serverConfig.extensionRepos)
@@ -218,7 +239,12 @@ class SettingsMutation {
         val (clientMutationId) = input
 
         GlobalConfigManager.resetUserConfig()
-        val defaultServerConfig = ServerConfig({ GlobalConfigManager.config.getConfig(SERVER_CONFIG_MODULE_NAME) })
+        val defaultServerConfig =
+            ServerConfig {
+                GlobalConfigManager.config.getConfig(
+                    SERVER_CONFIG_MODULE_NAME,
+                )
+            }
 
         val settings = SettingsType(defaultServerConfig)
         updateSettings(settings)
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/graphql/types/SettingsType.kt b/server/src/main/kotlin/suwayomi/tachidesk/graphql/types/SettingsType.kt
index d0002a90..6b5c65f3 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/graphql/types/SettingsType.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/graphql/types/SettingsType.kt
@@ -48,6 +48,7 @@ interface Settings : Node {
     val autoDownloadAheadLimit: Int?
     val autoDownloadNewChaptersLimit: Int?
     val autoDownloadIgnoreReUploads: Boolean?
+    val downloadConversions: List<SettingsDownloadConversion>?
 
     // extension
     val extensionRepos: List<String>?
@@ -113,6 +114,18 @@ interface Settings : Node {
     val opdsChapterSortOrder: SortOrder?
 }
 
+interface SettingsDownloadConversion {
+    val mimeType: String
+    val target: String
+    val compressionLevel: Float?
+}
+
+class SettingsDownloadConversionType(
+    override val mimeType: String,
+    override val target: String,
+    override val compressionLevel: Float?,
+) : SettingsDownloadConversion
+
 data class PartialSettingsType(
     override val ip: String?,
     override val port: Int?,
@@ -142,6 +155,7 @@ data class PartialSettingsType(
     override val autoDownloadAheadLimit: Int?,
     override val autoDownloadNewChaptersLimit: Int?,
     override val autoDownloadIgnoreReUploads: Boolean?,
+    override val downloadConversions: List<SettingsDownloadConversionType>?,
     // extension
     override val extensionRepos: List<String>?,
     // requests
@@ -222,7 +236,8 @@ class SettingsType(
     )
     override val autoDownloadAheadLimit: Int,
     override val autoDownloadNewChaptersLimit: Int,
-    override val autoDownloadIgnoreReUploads: Boolean?,
+    override val autoDownloadIgnoreReUploads: Boolean,
+    override val downloadConversions: List<SettingsDownloadConversionType>,
     // extension
     override val extensionRepos: List<String>,
     // requests
@@ -299,6 +314,13 @@ class SettingsType(
         config.autoDownloadNewChaptersLimit.value, // deprecated
         config.autoDownloadNewChaptersLimit.value,
         config.autoDownloadIgnoreReUploads.value,
+        config.downloadConversions.value.map {
+            SettingsDownloadConversionType(
+                it.key,
+                it.value.target,
+                it.value.compressionLevel,
+            )
+        },
         // extension
         config.extensionRepos.value,
         // requests
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/controller/MangaController.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/controller/MangaController.kt
index 5a918891..c875d15b 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/controller/MangaController.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/controller/MangaController.kt
@@ -403,6 +403,7 @@ object MangaController {
             pathParam<Int>("chapterIndex"),
             pathParam<Int>("index"),
             queryParam<Boolean?>("updateProgress"),
+            queryParam<String?>("format"),
             documentWith = {
                 withOperation {
                     summary("Get a chapter page")
@@ -411,9 +412,9 @@ object MangaController {
                     )
                 }
             },
-            behaviorOf = { ctx, mangaId, chapterIndex, index, updateProgress ->
+            behaviorOf = { ctx, mangaId, chapterIndex, index, updateProgress, format ->
                 ctx.future {
-                    future { Page.getPageImage(mangaId, chapterIndex, index, null) }
+                    future { Page.getPageImage(mangaId, chapterIndex, index, format, null) }
                         .thenApply {
                             ctx.header("content-type", it.second)
                             val httpCacheSeconds = 1.days.inWholeSeconds
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Page.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Page.kt
index 19c4f9bc..d8e1cf41 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Page.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/Page.kt
@@ -11,6 +11,7 @@ import eu.kanade.tachiyomi.source.local.LocalSource
 import eu.kanade.tachiyomi.source.model.Page
 import eu.kanade.tachiyomi.source.online.HttpSource
 import kotlinx.coroutines.flow.StateFlow
+import libcore.net.MimeUtils
 import org.jetbrains.exposed.sql.SortOrder
 import org.jetbrains.exposed.sql.and
 import org.jetbrains.exposed.sql.selectAll
@@ -23,8 +24,12 @@ import suwayomi.tachidesk.manga.impl.util.storage.ImageUtil
 import suwayomi.tachidesk.manga.model.table.ChapterTable
 import suwayomi.tachidesk.manga.model.table.MangaTable
 import suwayomi.tachidesk.manga.model.table.PageTable
+import suwayomi.tachidesk.util.ConversionUtil
+import java.io.ByteArrayInputStream
+import java.io.ByteArrayOutputStream
 import java.io.File
 import java.io.InputStream
+import javax.imageio.ImageIO
 
 object Page {
     /**
@@ -45,6 +50,7 @@ object Page {
         mangaId: Int,
         chapterIndex: Int,
         index: Int,
+        format: String? = null,
         progressFlow: ((StateFlow<Int>) -> Unit)? = null,
     ): Pair<InputStream, String> {
         val mangaEntry = transaction { MangaTable.selectAll().where { MangaTable.id eq mangaId }.first() }
@@ -61,7 +67,7 @@ object Page {
 
         try {
             if (chapterEntry[ChapterTable.isDownloaded]) {
-                return ChapterDownloadHelper.getImage(mangaId, chapterId, index)
+                return convertImageResponse(ChapterDownloadHelper.getImage(mangaId, chapterId, index), format)
             }
         } catch (_: Exception) {
             // ignore and fetch again
@@ -90,12 +96,15 @@ object Page {
             // is of archive format
             if (LocalSource.pageCache.containsKey(chapterEntry[ChapterTable.url])) {
                 val pageStream = LocalSource.pageCache[chapterEntry[ChapterTable.url]]!![index]
-                return pageStream() to (ImageUtil.findImageType { pageStream() }?.mime ?: "image/jpeg")
+                return convertImageResponse(pageStream() to (ImageUtil.findImageType { pageStream() }?.mime ?: "image/jpeg"), format)
             }
 
             // is of directory format
             val imageFile = File(tachiyomiPage.imageUrl!!)
-            return imageFile.inputStream() to (ImageUtil.findImageType { imageFile.inputStream() }?.mime ?: "image/jpeg")
+            return convertImageResponse(
+                imageFile.inputStream() to (ImageUtil.findImageType { imageFile.inputStream() }?.mime ?: "image/jpeg"),
+                format,
+            )
         }
 
         val source = getCatalogueSourceOrStub(mangaEntry[MangaTable.sourceReference])
@@ -115,9 +124,38 @@ object Page {
         val cacheSaveDir = getChapterCachePath(mangaId, chapterId)
 
         // Note: don't care about invalidating cache because OS cache is not permanent
-        return getImageResponse(cacheSaveDir, fileName) {
-            source.getImage(tachiyomiPage)
+        return convertImageResponse(
+            getImageResponse(cacheSaveDir, fileName) {
+                source.getImage(tachiyomiPage)
+            },
+            format,
+        )
+    }
+
+    private suspend fun convertImageResponse(
+        image: Pair<InputStream, String>,
+        format: String? = null,
+    ): Pair<InputStream, String> {
+        val imageExtension = MimeUtils.guessExtensionFromMimeType(image.second) ?: image.second.removePrefix("image/")
+
+        val targetExtension =
+            (if (format != imageExtension) format else null)
+                ?: return image
+
+        val outStream = ByteArrayOutputStream()
+        val writers = ImageIO.getImageWritersBySuffix(targetExtension)
+        val writer = writers.next()
+        ImageIO.createImageOutputStream(outStream).use { o ->
+            writer.setOutput(o)
+
+            val inImage =
+                ConversionUtil.readImage(image.first, image.second)
+                    ?: throw NoSuchElementException("No conversion to $targetExtension possible")
+            writer.write(inImage)
         }
+        writer.dispose()
+        val inStream = ByteArrayInputStream(outStream.toByteArray())
+        return Pair(inStream.buffered(), MimeUtils.guessMimeTypeFromExtension(targetExtension) ?: "image/$targetExtension")
     }
 
     /** converts 0 to "001" */
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/ProtoBackupExport.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/ProtoBackupExport.kt
index 47a1a0d4..d7846d1e 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/ProtoBackupExport.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/ProtoBackupExport.kt
@@ -37,6 +37,7 @@ import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupChapter
 import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupHistory
 import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupManga
 import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupServerSettings
+import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupServerSettings.BackupSettingsDownloadConversionType
 import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupSource
 import suwayomi.tachidesk.manga.impl.backup.proto.models.BackupTracking
 import suwayomi.tachidesk.manga.impl.track.Track
@@ -408,6 +409,14 @@ object ProtoBackupExport : ProtoBackupBase() {
             autoDownloadAheadLimit = 0, // deprecated
             autoDownloadNewChaptersLimit = serverConfig.autoDownloadNewChaptersLimit.value,
             autoDownloadIgnoreReUploads = serverConfig.autoDownloadIgnoreReUploads.value,
+            downloadConversions =
+                serverConfig.downloadConversions.value.map {
+                    BackupSettingsDownloadConversionType(
+                        it.key,
+                        it.value.target,
+                        it.value.compressionLevel,
+                    )
+                },
             // extension
             extensionRepos = serverConfig.extensionRepos.value,
             // requests
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/models/BackupServerSettings.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/models/BackupServerSettings.kt
index 64ba171b..89b14e04 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/models/BackupServerSettings.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/backup/proto/models/BackupServerSettings.kt
@@ -5,6 +5,7 @@ import kotlinx.serialization.protobuf.ProtoNumber
 import org.jetbrains.exposed.sql.SortOrder
 import suwayomi.tachidesk.graphql.types.AuthMode
 import suwayomi.tachidesk.graphql.types.Settings
+import suwayomi.tachidesk.graphql.types.SettingsDownloadConversion
 import suwayomi.tachidesk.graphql.types.WebUIChannel
 import suwayomi.tachidesk.graphql.types.WebUIFlavor
 import suwayomi.tachidesk.graphql.types.WebUIInterface
@@ -35,6 +36,7 @@ data class BackupServerSettings(
     @ProtoNumber(19) override var autoDownloadAheadLimit: Int,
     @ProtoNumber(20) override var autoDownloadNewChaptersLimit: Int,
     @ProtoNumber(21) override var autoDownloadIgnoreReUploads: Boolean,
+    @ProtoNumber(57) override val downloadConversions: List<BackupSettingsDownloadConversionType>?,
     // extension
     @ProtoNumber(22) override var extensionRepos: List<String>,
     // requests
@@ -82,4 +84,11 @@ data class BackupServerSettings(
     @ProtoNumber(53) override var opdsShowOnlyUnreadChapters: Boolean,
     @ProtoNumber(54) override var opdsShowOnlyDownloadedChapters: Boolean,
     @ProtoNumber(55) override var opdsChapterSortOrder: SortOrder,
-) : Settings
+) : Settings {
+    @Serializable
+    class BackupSettingsDownloadConversionType(
+        @ProtoNumber(1) override val mimeType: String,
+        @ProtoNumber(2) override val target: String,
+        @ProtoNumber(3) override val compressionLevel: Float?,
+    ) : SettingsDownloadConversion
+}
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/ChaptersFilesProvider.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/ChaptersFilesProvider.kt
index e85c5645..cdb93c06 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/ChaptersFilesProvider.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/ChaptersFilesProvider.kt
@@ -1,6 +1,7 @@
 package suwayomi.tachidesk.manga.impl.download.fileProvider
 
 import eu.kanade.tachiyomi.source.local.metadata.COMIC_INFO_FILE
+import io.github.oshai.kotlinlogging.KotlinLogging
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.Job
@@ -8,6 +9,7 @@ import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.sample
+import libcore.net.MimeUtils
 import org.apache.commons.compress.archivers.zip.ZipArchiveEntry
 import org.jetbrains.exposed.sql.SqlExpressionBuilder.eq
 import org.jetbrains.exposed.sql.selectAll
@@ -21,8 +23,14 @@ import suwayomi.tachidesk.manga.impl.util.getChapterDownloadPath
 import suwayomi.tachidesk.manga.impl.util.storage.ImageResponse
 import suwayomi.tachidesk.manga.model.table.ChapterTable
 import suwayomi.tachidesk.manga.model.table.MangaTable
+import suwayomi.tachidesk.server.serverConfig
+import suwayomi.tachidesk.util.ConversionUtil
 import java.io.File
+import java.io.IOException
 import java.io.InputStream
+import javax.imageio.IIOImage
+import javax.imageio.ImageIO
+import javax.imageio.ImageWriteParam
 
 sealed class FileType {
     data class RegularFile(
@@ -61,6 +69,8 @@ abstract class ChaptersFilesProvider<Type : FileType>(
     val mangaId: Int,
     val chapterId: Int,
 ) : DownloadedFilesProvider {
+    protected val logger = KotlinLogging.logger {}
+
     protected abstract fun getImageFiles(): List<Type>
 
     protected abstract fun getImageInputStream(image: Type): InputStream
@@ -75,7 +85,7 @@ abstract class ChaptersFilesProvider<Type : FileType>(
         val image = images[index]
         val imageFileType = image.getExtension()
 
-        return Pair(getImageInputStream(image).buffered(), "image/$imageFileType")
+        return Pair(getImageInputStream(image).buffered(), MimeUtils.guessMimeTypeFromExtension(imageFileType) ?: "image/$imageFileType")
     }
 
     fun getImageCount(): Int = getImageFiles().filter { it.getName() != COMIC_INFO_FILE }.size
@@ -166,6 +176,8 @@ abstract class ChaptersFilesProvider<Type : FileType>(
             },
         )
 
+        maybeConvertChapterImages(downloadCacheFolder)
+
         handleSuccessfulDownload()
 
         transaction {
@@ -185,4 +197,64 @@ abstract class ChaptersFilesProvider<Type : FileType>(
     abstract override fun delete(): Boolean
 
     abstract fun getAsArchiveStream(): Pair<InputStream, Long>
+
+    private fun maybeConvertChapterImages(chapterCacheFolder: File) {
+        if (chapterCacheFolder.isDirectory) {
+            val conv = serverConfig.downloadConversions.value
+            chapterCacheFolder
+                .listFiles()
+                .orEmpty()
+                .filter { it.name != COMIC_INFO_FILE }
+                .forEach {
+                    val imageType = MimeUtils.guessMimeTypeFromExtension(it.extension) ?: return@forEach
+                    val targetConversion =
+                        conv.getOrElse(imageType) {
+                            conv.getOrElse("default") {
+                                logger.debug { "Skipping conversion of $it since no conversion specified" }
+                                return@forEach
+                            }
+                        }
+                    val targetMime = targetConversion.target
+                    if (imageType == targetMime || targetMime == "none") return@forEach // nothing to do
+                    logger.debug { "Converting $it to $targetMime" }
+                    val targetExtension = MimeUtils.guessExtensionFromMimeType(targetMime) ?: targetMime.removePrefix("image/")
+
+                    val outFile = File(it.parentFile, it.nameWithoutExtension + "." + targetExtension)
+
+                    val writers = ImageIO.getImageWritersByMIMEType(targetMime)
+                    val writer =
+                        try {
+                            writers.next()
+                        } catch (_: NoSuchElementException) {
+                            logger.warn { "Conversion aborted: No reader for target format $targetMime" }
+                            return@forEach
+                        }
+                    val writerParams = writer.defaultWriteParam
+                    targetConversion.compressionLevel?.let {
+                        writerParams.compressionMode = ImageWriteParam.MODE_EXPLICIT
+                        writerParams.compressionQuality = it
+                    }
+                    val success =
+                        try {
+                            ImageIO.createImageOutputStream(outFile)
+                        } catch (e: IOException) {
+                            logger.warn(e) { "Conversion aborted" }
+                            return@forEach
+                        }.use { outStream ->
+                            writer.setOutput(outStream)
+
+                            val inImage = ConversionUtil.readImage(it) ?: return@use false
+                            writer.write(null, IIOImage(inImage, null, null), writerParams)
+                            return@use true
+                        }
+                    writer.dispose()
+                    if (success) {
+                        it.delete()
+                    } else {
+                        logger.warn { "Conversion aborted: No reader for image $it" }
+                        outFile.delete()
+                    }
+                }
+        }
+    }
 }
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/FileRetriever.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/FileRetriever.kt
index 81c09f80..75bffaf2 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/FileRetriever.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/fileProvider/FileRetriever.kt
@@ -19,6 +19,16 @@ fun interface RetrieveFile1Args<A> : RetrieveFile {
     override fun executeGetImage(vararg args: Any): Pair<InputStream, String> = execute(args[0] as A)
 }
 
+@Suppress("UNCHECKED_CAST")
+fun interface RetrieveFile2Args<A, B> : RetrieveFile {
+    fun execute(
+        a: A,
+        b: B,
+    ): Pair<InputStream, String>
+
+    override fun executeGetImage(vararg args: Any): Pair<InputStream, String> = execute(args[0] as A, args[1] as B)
+}
+
 fun interface FileRetriever {
     fun getImage(): RetrieveFile
 }
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/track/tracker/kitsu/KitsuApi.kt b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/track/tracker/kitsu/KitsuApi.kt
index 0724f6f5..40345a1e 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/track/tracker/kitsu/KitsuApi.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/manga/impl/track/tracker/kitsu/KitsuApi.kt
@@ -29,7 +29,6 @@ import suwayomi.tachidesk.manga.impl.track.tracker.model.Track
 import suwayomi.tachidesk.manga.impl.track.tracker.model.TrackSearch
 import uy.kohesive.injekt.injectLazy
 import java.net.URLEncoder
-import java.nio.charset.StandardCharsets
 
 class KitsuApi(
     private val client: OkHttpClient,
@@ -151,7 +150,7 @@ class KitsuApi(
         withIOContext {
             val jsonObject =
                 buildJsonObject {
-                    put("params", "query=${URLEncoder.encode(query, StandardCharsets.UTF_8.name())}$ALGOLIA_FILTER")
+                    put("params", "query=${URLEncoder.encode(query, Charsets.UTF_8)}$ALGOLIA_FILTER")
                 }
 
             with(json) {
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/opds/util/OpdsStringUtil.kt b/server/src/main/kotlin/suwayomi/tachidesk/opds/util/OpdsStringUtil.kt
index e05120d2..22b1c5d4 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/opds/util/OpdsStringUtil.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/opds/util/OpdsStringUtil.kt
@@ -2,7 +2,6 @@ package suwayomi.tachidesk.opds.util
 
 import suwayomi.tachidesk.server.serverConfig
 import java.net.URLEncoder
-import java.nio.charset.StandardCharsets
 import java.text.Normalizer
 
 /**
@@ -15,7 +14,7 @@ object OpdsStringUtil {
      * Encodes a string to be used in OPDS URLs.
      * @return The URL-encoded string
      */
-    fun String.encodeForOpdsURL(): String = URLEncoder.encode(this, StandardCharsets.UTF_8.toString())
+    fun String.encodeForOpdsURL(): String = URLEncoder.encode(this, Charsets.UTF_8)
 
     /**
      * Converts a string into a URL-friendly slug.
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/server/ConfigAdapters.kt b/server/src/main/kotlin/suwayomi/tachidesk/server/ConfigAdapters.kt
deleted file mode 100644
index 8276bed6..00000000
--- a/server/src/main/kotlin/suwayomi/tachidesk/server/ConfigAdapters.kt
+++ /dev/null
@@ -1,27 +0,0 @@
-package suwayomi.tachidesk.server
-
-interface ConfigAdapter<T> {
-    fun toType(configValue: String): T
-}
-
-object StringConfigAdapter : ConfigAdapter<String> {
-    override fun toType(configValue: String): String = configValue
-}
-
-object IntConfigAdapter : ConfigAdapter<Int> {
-    override fun toType(configValue: String): Int = configValue.toInt()
-}
-
-object BooleanConfigAdapter : ConfigAdapter<Boolean> {
-    override fun toType(configValue: String): Boolean = configValue.toBoolean()
-}
-
-object DoubleConfigAdapter : ConfigAdapter<Double> {
-    override fun toType(configValue: String): Double = configValue.toDouble()
-}
-
-class EnumConfigAdapter<T : Enum<T>>(
-    private val enumClass: Class<T>,
-) : ConfigAdapter<T> {
-    override fun toType(configValue: String): T = java.lang.Enum.valueOf(enumClass, configValue.uppercase())
-}
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/server/JavalinSetup.kt b/server/src/main/kotlin/suwayomi/tachidesk/server/JavalinSetup.kt
index 9cff65b3..dc818351 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/server/JavalinSetup.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/server/JavalinSetup.kt
@@ -33,7 +33,6 @@ import suwayomi.tachidesk.server.util.WebInterfaceManager
 import uy.kohesive.injekt.injectLazy
 import java.io.IOException
 import java.net.URLEncoder
-import java.nio.charset.StandardCharsets
 import java.util.concurrent.CompletableFuture
 import kotlin.concurrent.thread
 import kotlin.time.Duration.Companion.days
@@ -168,7 +167,7 @@ object JavalinSetup {
                 return@beforeMatched
             }
 
-            val authMode = serverConfig.authMode.value ?: AuthMode.NONE
+            val authMode = serverConfig.authMode.value
 
             fun credentialsValid(): Boolean {
                 val basicAuthCredentials = ctx.basicAuthCredentials() ?: return false
@@ -187,7 +186,7 @@ object JavalinSetup {
             }
 
             if (authMode == AuthMode.SIMPLE_LOGIN && !cookieValid()) {
-                val url = "/login.html?redirect=" + URLEncoder.encode(ctx.fullUrl(), StandardCharsets.UTF_8)
+                val url = "/login.html?redirect=" + URLEncoder.encode(ctx.fullUrl(), Charsets.UTF_8)
                 ctx.header("Location", url)
                 throw RedirectResponse(HttpStatus.SEE_OTHER)
             }
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/server/ServerConfig.kt b/server/src/main/kotlin/suwayomi/tachidesk/server/ServerConfig.kt
index 7b2ec743..1b68b7c5 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/server/ServerConfig.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/server/ServerConfig.kt
@@ -8,6 +8,7 @@ package suwayomi.tachidesk.server
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 import com.typesafe.config.Config
+import io.github.config4k.getValue
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -38,39 +39,29 @@ const val SERVER_CONFIG_MODULE_NAME = "server"
 
 class ServerConfig(
     getConfig: () -> Config,
-    val moduleName: String = SERVER_CONFIG_MODULE_NAME,
 ) : SystemPropertyOverridableConfigModule(
         getConfig,
-        moduleName,
+        SERVER_CONFIG_MODULE_NAME,
     ) {
-    open inner class OverrideConfigValue<T>(
-        private val configAdapter: ConfigAdapter<out Any>,
-    ) {
-        private var flow: MutableStateFlow<T>? = null
+    open inner class OverrideConfigValue {
+        var flow: MutableStateFlow<Any>? = null
 
-        open fun getValueFromConfig(
+        inline operator fun <reified T : MutableStateFlow<R>, reified R> getValue(
             thisRef: ServerConfig,
             property: KProperty<*>,
-        ): Any = configAdapter.toType(overridableConfig.getValue<ServerConfig, String>(thisRef, property))
-
-        operator fun getValue(
-            thisRef: ServerConfig,
-            property: KProperty<*>,
-        ): MutableStateFlow<T> {
+        ): T {
             if (flow != null) {
-                return flow!!
+                return flow as T
             }
 
+            val stateFlow = overridableConfig.getValue<ServerConfig, T>(thisRef, property)
             @Suppress("UNCHECKED_CAST")
-            val value = getValueFromConfig(thisRef, property) as T
-
-            val stateFlow = MutableStateFlow(value)
-            flow = stateFlow
+            flow = stateFlow as MutableStateFlow<Any>
 
             stateFlow
                 .drop(1)
                 .distinctUntilChanged()
-                .filter { it != getValueFromConfig(thisRef, property) }
+                .filter { it != thisRef.overridableConfig.getConfig().getValue<ServerConfig, R>(thisRef, property) }
                 .onEach { GlobalConfigManager.updateValue("$moduleName.${property.name}", it as Any) }
                 .launchIn(mutableConfigValueScope)
 
@@ -78,29 +69,12 @@ class ServerConfig(
         }
     }
 
-    inner class OverrideConfigValues<T>(
-        private val configAdapter: ConfigAdapter<out Any>,
-    ) : OverrideConfigValue<T>(configAdapter) {
-        override fun getValueFromConfig(
-            thisRef: ServerConfig,
-            property: KProperty<*>,
-        ): Any =
-            overridableConfig
-                .getValue<ServerConfig, List<String>>(thisRef, property)
-                .map { configAdapter.toType(it) }
-    }
-
     open inner class MigratedConfigValue<T>(
-        private val readMigrated: () -> Any,
+        private val readMigrated: () -> T,
         private val setMigrated: (T) -> Unit,
     ) {
         private var flow: MutableStateFlow<T>? = null
 
-        open fun getValueFromConfig(
-            thisRef: ServerConfig,
-            property: KProperty<*>,
-        ): Any = readMigrated()
-
         operator fun getValue(
             thisRef: ServerConfig,
             property: KProperty<*>,
@@ -109,8 +83,7 @@ class ServerConfig(
                 return flow!!
             }
 
-            @Suppress("UNCHECKED_CAST")
-            val value = getValueFromConfig(thisRef, property) as T
+            val value = readMigrated()
 
             val stateFlow = MutableStateFlow(value)
             flow = stateFlow
@@ -118,7 +91,7 @@ class ServerConfig(
             stateFlow
                 .drop(1)
                 .distinctUntilChanged()
-                .filter { it != getValueFromConfig(thisRef, property) }
+                .filter { it != readMigrated() }
                 .onEach(setMigrated)
                 .launchIn(mutableConfigValueScope)
 
@@ -126,51 +99,57 @@ class ServerConfig(
         }
     }
 
-    val ip: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val port: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
+    val ip: MutableStateFlow<String> by OverrideConfigValue()
+    val port: MutableStateFlow<Int> by OverrideConfigValue()
 
     // proxy
-    val socksProxyEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val socksProxyVersion: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val socksProxyHost: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val socksProxyPort: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val socksProxyUsername: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val socksProxyPassword: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
+    val socksProxyEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val socksProxyVersion: MutableStateFlow<Int> by OverrideConfigValue()
+    val socksProxyHost: MutableStateFlow<String> by OverrideConfigValue()
+    val socksProxyPort: MutableStateFlow<String> by OverrideConfigValue()
+    val socksProxyUsername: MutableStateFlow<String> by OverrideConfigValue()
+    val socksProxyPassword: MutableStateFlow<String> by OverrideConfigValue()
 
     // webUI
-    val webUIEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val webUIFlavor: MutableStateFlow<WebUIFlavor> by OverrideConfigValue(EnumConfigAdapter(WebUIFlavor::class.java))
-    val initialOpenInBrowserEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val webUIInterface: MutableStateFlow<WebUIInterface> by OverrideConfigValue(EnumConfigAdapter(WebUIInterface::class.java))
-    val electronPath: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val webUIChannel: MutableStateFlow<WebUIChannel> by OverrideConfigValue(EnumConfigAdapter(WebUIChannel::class.java))
-    val webUIUpdateCheckInterval: MutableStateFlow<Double> by OverrideConfigValue(DoubleConfigAdapter)
+    val webUIEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val webUIFlavor: MutableStateFlow<WebUIFlavor> by OverrideConfigValue()
+    val initialOpenInBrowserEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val webUIInterface: MutableStateFlow<WebUIInterface> by OverrideConfigValue()
+    val electronPath: MutableStateFlow<String> by OverrideConfigValue()
+    val webUIChannel: MutableStateFlow<WebUIChannel> by OverrideConfigValue()
+    val webUIUpdateCheckInterval: MutableStateFlow<Double> by OverrideConfigValue()
 
     // downloader
-    val downloadAsCbz: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val downloadsPath: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val autoDownloadNewChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val excludeEntryWithUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val autoDownloadNewChaptersLimit: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val autoDownloadIgnoreReUploads: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
+    val downloadAsCbz: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val downloadsPath: MutableStateFlow<String> by OverrideConfigValue()
+    val autoDownloadNewChapters: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val excludeEntryWithUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val autoDownloadNewChaptersLimit: MutableStateFlow<Int> by OverrideConfigValue()
+    val autoDownloadIgnoreReUploads: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val downloadConversions: MutableStateFlow<Map<String, DownloadConversion>> by OverrideConfigValue()
+
+    data class DownloadConversion(
+        val target: String,
+        val compressionLevel: Float? = null,
+    )
 
     // extensions
-    val extensionRepos: MutableStateFlow<List<String>> by OverrideConfigValues(StringConfigAdapter)
+    val extensionRepos: MutableStateFlow<List<String>> by OverrideConfigValue()
 
     // requests
-    val maxSourcesInParallel: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
+    val maxSourcesInParallel: MutableStateFlow<Int> by OverrideConfigValue()
 
     // updater
-    val excludeUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val excludeNotStarted: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val excludeCompleted: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val globalUpdateInterval: MutableStateFlow<Double> by OverrideConfigValue(DoubleConfigAdapter)
-    val updateMangas: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
+    val excludeUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val excludeNotStarted: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val excludeCompleted: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val globalUpdateInterval: MutableStateFlow<Double> by OverrideConfigValue()
+    val updateMangas: MutableStateFlow<Boolean> by OverrideConfigValue()
 
     // Authentication
-    val authMode: MutableStateFlow<AuthMode> by OverrideConfigValue(EnumConfigAdapter(AuthMode::class.java))
-    val authUsername: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val authPassword: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
+    val authMode: MutableStateFlow<AuthMode> by OverrideConfigValue()
+    val authUsername: MutableStateFlow<String> by OverrideConfigValue()
+    val authPassword: MutableStateFlow<String> by OverrideConfigValue()
     val basicAuthEnabled: MutableStateFlow<Boolean> by MigratedConfigValue({
         authMode.value == AuthMode.BASIC_AUTH
     }) {
@@ -184,37 +163,37 @@ class ServerConfig(
     }
 
     // misc
-    val debugLogsEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val systemTrayEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val maxLogFiles: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val maxLogFileSize: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val maxLogFolderSize: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
+    val debugLogsEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val systemTrayEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val maxLogFiles: MutableStateFlow<Int> by OverrideConfigValue()
+    val maxLogFileSize: MutableStateFlow<String> by OverrideConfigValue()
+    val maxLogFolderSize: MutableStateFlow<String> by OverrideConfigValue()
 
     // backup
-    val backupPath: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val backupTime: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val backupInterval: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val backupTTL: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
+    val backupPath: MutableStateFlow<String> by OverrideConfigValue()
+    val backupTime: MutableStateFlow<String> by OverrideConfigValue()
+    val backupInterval: MutableStateFlow<Int> by OverrideConfigValue()
+    val backupTTL: MutableStateFlow<Int> by OverrideConfigValue()
 
     // local source
-    val localSourcePath: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
+    val localSourcePath: MutableStateFlow<String> by OverrideConfigValue()
 
     // cloudflare bypass
-    val flareSolverrEnabled: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val flareSolverrUrl: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val flareSolverrTimeout: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val flareSolverrSessionName: MutableStateFlow<String> by OverrideConfigValue(StringConfigAdapter)
-    val flareSolverrSessionTtl: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val flareSolverrAsResponseFallback: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
+    val flareSolverrEnabled: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val flareSolverrUrl: MutableStateFlow<String> by OverrideConfigValue()
+    val flareSolverrTimeout: MutableStateFlow<Int> by OverrideConfigValue()
+    val flareSolverrSessionName: MutableStateFlow<String> by OverrideConfigValue()
+    val flareSolverrSessionTtl: MutableStateFlow<Int> by OverrideConfigValue()
+    val flareSolverrAsResponseFallback: MutableStateFlow<Boolean> by OverrideConfigValue()
 
     // opds settings
-    val opdsUseBinaryFileSizes: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val opdsItemsPerPage: MutableStateFlow<Int> by OverrideConfigValue(IntConfigAdapter)
-    val opdsEnablePageReadProgress: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val opdsMarkAsReadOnDownload: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val opdsShowOnlyUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val opdsShowOnlyDownloadedChapters: MutableStateFlow<Boolean> by OverrideConfigValue(BooleanConfigAdapter)
-    val opdsChapterSortOrder: MutableStateFlow<SortOrder> by OverrideConfigValue(EnumConfigAdapter(SortOrder::class.java))
+    val opdsUseBinaryFileSizes: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val opdsItemsPerPage: MutableStateFlow<Int> by OverrideConfigValue()
+    val opdsEnablePageReadProgress: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val opdsMarkAsReadOnDownload: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val opdsShowOnlyUnreadChapters: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val opdsShowOnlyDownloadedChapters: MutableStateFlow<Boolean> by OverrideConfigValue()
+    val opdsChapterSortOrder: MutableStateFlow<SortOrder> by OverrideConfigValue()
 
     @OptIn(ExperimentalCoroutinesApi::class)
     fun <T> subscribeTo(
@@ -259,6 +238,11 @@ class ServerConfig(
     }
 
     companion object {
-        fun register(getConfig: () -> Config) = ServerConfig({ getConfig().getConfig(SERVER_CONFIG_MODULE_NAME) })
+        fun register(getConfig: () -> Config) =
+            ServerConfig {
+                getConfig().getConfig(
+                    SERVER_CONFIG_MODULE_NAME,
+                )
+            }
     }
 }
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/server/ServerSetup.kt b/server/src/main/kotlin/suwayomi/tachidesk/server/ServerSetup.kt
index 574db087..fbaf5550 100644
--- a/server/src/main/kotlin/suwayomi/tachidesk/server/ServerSetup.kt
+++ b/server/src/main/kotlin/suwayomi/tachidesk/server/ServerSetup.kt
@@ -13,13 +13,14 @@ import com.typesafe.config.Config
 import com.typesafe.config.ConfigException
 import com.typesafe.config.ConfigRenderOptions
 import com.typesafe.config.ConfigValue
-import com.typesafe.config.ConfigValueFactory
 import com.typesafe.config.parser.ConfigDocument
 import dev.datlag.kcef.KCEF
 import eu.kanade.tachiyomi.App
 import eu.kanade.tachiyomi.createAppModule
 import eu.kanade.tachiyomi.network.NetworkHelper
 import eu.kanade.tachiyomi.source.local.LocalSource
+import io.github.config4k.registerCustomType
+import io.github.config4k.toConfig
 import io.github.oshai.kotlinlogging.KotlinLogging
 import io.javalin.json.JavalinJackson
 import io.javalin.json.JsonMapper
@@ -44,10 +45,10 @@ import suwayomi.tachidesk.manga.impl.download.DownloadManager
 import suwayomi.tachidesk.manga.impl.update.IUpdater
 import suwayomi.tachidesk.manga.impl.update.Updater
 import suwayomi.tachidesk.manga.impl.util.lang.renameTo
-import suwayomi.tachidesk.server.BooleanConfigAdapter
 import suwayomi.tachidesk.server.database.databaseUp
 import suwayomi.tachidesk.server.generated.BuildConfig
 import suwayomi.tachidesk.server.util.AppMutex.handleAppMutex
+import suwayomi.tachidesk.server.util.MutableStateFlowType
 import suwayomi.tachidesk.server.util.SystemTray
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
@@ -147,7 +148,7 @@ fun <T : Any> migrateConfig(
         if (typedValue != null) {
             return configDocument.withValue(
                 toConfigKey,
-                ConfigValueFactory.fromAnyRef(typedValue),
+                typedValue.toConfig("internal").getValue("internal"),
             )
         }
     } catch (_: ConfigException) {
@@ -174,6 +175,7 @@ fun applicationSetup() {
     mainLoop.start()
 
     // register Tachidesk's config which is dubbed "ServerConfig"
+    registerCustomType(MutableStateFlowType())
     GlobalConfigManager.registerModule(
         ServerConfig.register { GlobalConfigManager.config },
     )
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/server/util/MutableStateFlowType.kt b/server/src/main/kotlin/suwayomi/tachidesk/server/util/MutableStateFlowType.kt
new file mode 100644
index 00000000..b3159811
--- /dev/null
+++ b/server/src/main/kotlin/suwayomi/tachidesk/server/util/MutableStateFlowType.kt
@@ -0,0 +1,39 @@
+package suwayomi.tachidesk.server.util
+
+import com.typesafe.config.Config
+import io.github.config4k.ClassContainer
+import io.github.config4k.CustomType
+import io.github.config4k.readers.SelectReader
+import io.github.config4k.toConfig
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+
+class MutableStateFlowType : CustomType {
+    override fun parse(
+        clazz: ClassContainer,
+        config: Config,
+        name: String,
+    ): Any? {
+        val reader =
+            SelectReader.getReader(
+                clazz.typeArguments.entries
+                    .first()
+                    .value,
+            )
+        val path = name
+        val result = reader(config, path)
+        return MutableStateFlow(result)
+    }
+
+    override fun testParse(clazz: ClassContainer): Boolean =
+        clazz.mapperClass.qualifiedName == "kotlinx.coroutines.flow.MutableStateFlow" ||
+            clazz.mapperClass.qualifiedName == "kotlinx.coroutines.flow.StateFlow" ||
+            clazz.mapperClass.qualifiedName == "kotlinx.coroutines.flow.StateFlowImpl"
+
+    override fun testToConfig(obj: Any): Boolean = (obj as? StateFlow<*>)?.value != null
+
+    override fun toConfig(
+        obj: Any,
+        name: String,
+    ): Config = (obj as StateFlow<*>).value!!.toConfig(name)
+}
diff --git a/server/src/main/kotlin/suwayomi/tachidesk/util/ConversionUtil.kt b/server/src/main/kotlin/suwayomi/tachidesk/util/ConversionUtil.kt
new file mode 100644
index 00000000..2279837c
--- /dev/null
+++ b/server/src/main/kotlin/suwayomi/tachidesk/util/ConversionUtil.kt
@@ -0,0 +1,52 @@
+package suwayomi.tachidesk.util
+
+import io.github.oshai.kotlinlogging.KotlinLogging
+import java.awt.image.BufferedImage
+import java.io.File
+import java.io.InputStream
+import javax.imageio.ImageIO
+
+object ConversionUtil {
+    val logger = KotlinLogging.logger {}
+
+    public fun readImage(image: File): BufferedImage? {
+        val readers = ImageIO.getImageReadersBySuffix(image.extension)
+        image.inputStream().use {
+            ImageIO.createImageInputStream(it).use { inputStream ->
+                for (reader in readers) {
+                    try {
+                        reader.setInput(inputStream)
+                        return reader.read(0)
+                    } catch (e: Throwable) {
+                        logger.debug(e) { "Reader ${reader.javaClass.name} not suitable" }
+                    } finally {
+                        reader.dispose()
+                    }
+                }
+            }
+        }
+        logger.info { "No suitable image converter found for ${image.name}" }
+        return null
+    }
+
+    public fun readImage(
+        image: InputStream,
+        mimeType: String,
+    ): BufferedImage? {
+        val readers = ImageIO.getImageReadersByMIMEType(mimeType)
+        ImageIO.createImageInputStream(image).use { inputStream ->
+            for (reader in readers) {
+                try {
+                    reader.setInput(inputStream)
+                    return reader.read(0)
+                } catch (e: Throwable) {
+                    logger.debug(e) { "Reader ${reader.javaClass.name} not suitable" }
+                } finally {
+                    reader.dispose()
+                }
+            }
+        }
+        logger.info { "No suitable image converter found for $mimeType" }
+        return null
+    }
+}
diff --git a/server/src/main/resources/server-reference.conf b/server/src/main/resources/server-reference.conf
index 86c6a9ae..6242b450 100644
--- a/server/src/main/resources/server-reference.conf
+++ b/server/src/main/resources/server-reference.conf
@@ -26,6 +26,12 @@ server.autoDownloadNewChapters = false # if new chapters that have been retrieve
 server.excludeEntryWithUnreadChapters = true # ignore automatic chapter downloads of entries with unread chapters
 server.autoDownloadNewChaptersLimit = 0 # 0 to disable it - how many unread downloaded chapters should be available - if the limit is reached, new chapters won't be downloaded automatically. this limit will also be applied to the auto download of new chapters on an update
 server.autoDownloadIgnoreReUploads = false # decides if re-uploads should be ignored during auto download of new chapters
+server.downloadConversions = {}
+# map input mime type to conversion information, or "default" for others
+# server.downloadConversions."image/webp" = {
+#   target = "image/jpeg"   # image type to convert to
+#   compressionLevel = 0.8  # quality in range [0,1], leave away to use default compression
+# }
 
 # extension repos
 server.extensionRepos = [
diff --git a/server/src/test/kotlin/suwayomi/tachidesk/manga/impl/update/TestUpdater.kt b/server/src/test/kotlin/suwayomi/tachidesk/manga/impl/update/TestUpdater.kt
index 3b319a50..c600cb91 100644
--- a/server/src/test/kotlin/suwayomi/tachidesk/manga/impl/update/TestUpdater.kt
+++ b/server/src/test/kotlin/suwayomi/tachidesk/manga/impl/update/TestUpdater.kt
@@ -31,6 +31,10 @@ class TestUpdater : IUpdater {
         TODO("Not yet implemented")
     }
 
+    override fun deleteLastAutomatedUpdateTimestamp() {
+        TODO("Not yet implemented")
+    }
+
     override fun addCategoriesToUpdateQueue(
         categories: List<CategoryDataClass>,
         clear: Boolean?,
diff --git a/server/src/test/resources/server-reference.conf b/server/src/test/resources/server-reference.conf
index 14ccfbe2..96f7420c 100644
--- a/server/src/test/resources/server-reference.conf
+++ b/server/src/test/resources/server-reference.conf
@@ -26,6 +26,12 @@ server.autoDownloadNewChapters = false # if new chapters that have been retrieve
 server.excludeEntryWithUnreadChapters = true # ignore automatic chapter downloads of entries with unread chapters
 server.autoDownloadNewChaptersLimit = 0 # 0 to disable it - how many unread downloaded chapters should be available - if the limit is reached, new chapters won't be downloaded automatically. this limit will also be applied to the auto download of new chapters on an update
 server.autoDownloadIgnoreReUploads = false # decides if re-uploads should be ignored during auto download of new chapters
+server.downloadConversions = {}
+# map input mime type to conversion information, or "default" for others
+# server.downloadConversions."image/webp" = {
+#   target = "image/jpeg"   # image type to convert to
+#   compressionLevel = 0.8  # quality in range [0,1], leave away to use default compression
+# }
 
 # extension repos
 server.extensionRepos = [