diff --git a/server/src/lib/image-resize.js b/server/src/lib/image-resize.js
index 4bd7c0f..e6378cc 100644
--- a/server/src/lib/image-resize.js
+++ b/server/src/lib/image-resize.js
@@ -77,13 +77,14 @@ export async function generateAllSizes(uuid, subdir, originalPath) {
   await fs.promises.mkdir(cacheDir, { recursive: true })
 
   const sharp = (await import('sharp')).default
+  const source = sharp(originalPath)
 
   for (const width of VALID_WIDTHS) {
     for (const format of SUPPORTED_FORMATS) {
       const cacheFileName = `${uuid}_w${width}.${format}`
       const cachePath = path.join(CACHE_DIR, cacheSubdir, cacheFileName)
 
-      const pipeline = sharp(originalPath).resize(width, null, { withoutEnlargement: true })
+      const pipeline = source.clone().resize(width, null, { withoutEnlargement: true })
       const options = format === 'avif' ? { quality: 75, effort: 4 } : { quality: 80 }
       await pipeline[format](options).toFile(cachePath)
     }
@@ -97,8 +98,7 @@ export async function generateAllSizes(uuid, subdir, originalPath) {
  * @returns {string} New URL path like `/uploads/<uuid>.webp`
  */
 export async function convertOriginalToWebp(uuid, subdir) {
-  const uploadsDir = path.join(process.cwd(), 'uploads')
-  const targetDir = subdir ? path.join(uploadsDir, subdir) : uploadsDir
+  const targetDir = subdir ? path.join(UPLOADS_DIR, subdir) : UPLOADS_DIR
 
   const originalPath = await findOriginalFile(uuid, subdir)
   if (!originalPath) {