Add an option to use immich previews (1440p) intead of full images

frontend/src/lib/components/SettingsPanel.svelte

@@ -41,6 +41,7 @@
       const configToSend = {
         processing: {
           max_workers: Number(config.processing.max_workers),
+          use_preview: config.processing.use_preview,
           face_resolution: {
             enabled: config.processing.face_resolution.enabled,
             min_size: Number(config.processing.face_resolution.min_size),
@@ -384,6 +385,14 @@
                     <span class="value">{config.processing.max_workers}</span>
                   </div>
                 </div>
+
+                <div class="setting-row checkbox-row">
+                  <label for="use-preview">
+                    <span class="setting-label">Use Preview Images</span>
+                    <span class="setting-hint">Download Immich 1440p previews instead of originals (much faster)</span>
+                  </label>
+                  <input id="use-preview" type="checkbox" bind:checked={config.processing.use_preview} />
+                </div>
               </div>
 
               <!-- Time Interval Section -->

frontend/src/lib/constants.js

@@ -50,6 +50,7 @@ export const JOB_STATUS = {
 export const DEFAULT_CONFIG = {
   processing: {
     max_workers: 4,
+    use_preview: true,
     face_resolution: {
       enabled: true,
       min_size: 80,

src/config.rs

@@ -495,6 +495,12 @@ pub struct ProcessingConfig {
     /// Number of parallel workers for processing.
     pub max_workers: usize,
 
+    /// Whether to download Immich preview images (1440p JPEG) instead of originals.
+    /// Preview images are much faster to decode and sufficient for most use cases.
+    /// Disable only if you need full original resolution (e.g., very small faces in high-res photos).
+    #[serde(default = "default_true")]
+    pub use_preview: bool,
+
     /// Face resolution validation settings.
     #[serde(default)]
     pub face_resolution: FaceResolutionConfig,
@@ -536,6 +542,7 @@ impl Default for ProcessingConfig {
     fn default() -> Self {
         Self {
             max_workers: num_cpus(),
+            use_preview: true,
             face_resolution: FaceResolutionConfig::default(),
             blur: BlurConfig::default(),
             brightness: BrightnessConfig::default(),
@@ -570,6 +577,10 @@ impl ProcessingConfig {
     }
 }
 
+fn default_true() -> bool {
+    true
+}
+
 fn num_cpus() -> usize {
     std::thread::available_parallelism()
         .map(|p| p.get())

src/immich_api/mod.rs

@@ -240,6 +240,33 @@ impl ImmichClient {
         Ok(bytes)
     }
 
+    /// Download an asset's preview image (1440p JPEG pre-generated by Immich).
+    ///
+    /// Much faster to download and decode than the original.
+    /// Falls back to the original if the preview is unavailable.
+    pub async fn download_asset_preview(&self, asset_id: &str) -> Result<bytes::Bytes> {
+        let encoded_id = urlencode(asset_id);
+        let url = format!("{}/assets/{}/thumbnail?size=preview", self.base_url, encoded_id);
+
+        let response = self
+            .client
+            .get(&url)
+            .header("x-api-key", &self.api_key)
+            .send()
+            .await?;
+
+        if !response.status().is_success() {
+            return Err(Error::ImmichApi(format!(
+                "Failed to download preview for asset {}: {}",
+                asset_id,
+                response.status()
+            )));
+        }
+
+        let bytes = response.bytes().await?;
+        Ok(bytes)
+    }
+
     /// Get all people from Immich.
     pub async fn get_people(&self) -> Result<Vec<Person>> {
         let url = format!("{}/people", self.base_url);

src/job/processing.rs

@@ -108,8 +108,13 @@ pub async fn process_single_asset(
         };
     }
 
-    // Download image
-    let image_bytes: Bytes = match client.download_asset(asset_id).await {
+    // Download image (preview or original based on config)
+    let download_result = if config.processing.use_preview {
+        client.download_asset_preview(asset_id).await
+    } else {
+        client.download_asset(asset_id).await
+    };
+    let image_bytes: Bytes = match download_result {
         Ok(bytes) => bytes,
         Err(e) => {
             skip_stats.increment("download_failed");