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Image Compressor

Use Sliprail's Image Compressor when email attachments, document images, website assets, or photo copies take more space than you want. It can process several supported images at once or scan a folder recursively in the Windows and macOS desktop apps.

Image Compressor keeps each supported file in its original format. It is not an image resizer or format converter, and it cannot target an exact file size such as 200 KB.

Open Image Compressor

  1. Open the Sliprail launcher
  2. Type CompressImages
  3. Press Enter to open the Image Compression window

Image Compressor is a built-in desktop extension and is not available in Sliprail Web. If the command is missing, open Settings > Extensions and check that Image Compression is enabled in a Sliprail version that includes it.

Choose images or drag in a folder

Choose the compression mode before adding files, then use either method:

  • Select Select Images to choose one or more images in the file picker
  • Drag one or more supported images or folders into the window

The file picker selects files only. To process a folder, drag it into the window. Sliprail scans dragged folders recursively, compresses supported images, and preserves their relative subfolder layout in the output. Other files in the folder are not copied.

Compression starts as soon as Sliprail accepts the selection or drop.

Drag-and-drop when Sliprail runs as administrator

Sliprail disables file drag-and-drop in this window when it is running as administrator on Windows. The drop prompt is hidden in that situation, but Select Images remains available. This restriction does not apply on macOS.

Choose a compression mode

  • Quality Priority is selected by default. It keeps more visible detail and aims for a moderate reduction
  • Balanced aims for a smaller output while keeping the image looking clear

Both modes re-encode images and can change image data. Use Quality Priority when detail matters most, and try Balanced when reducing transfer or storage size matters more.

Watch or stop progress

Sliprail first scans the selected paths and then compresses the images it found. The progress area shows:

  • Processed images and total images found
  • Original size, current output size, and space saved
  • A per-file result such as Compressed, Unchanged, Skipped, or Failed
  • The original and output sizes for each processed image

Select Stop Compression while Sliprail is scanning or compressing to request cancellation. This stops the batch rather than pausing it. Files that finished before the stop are kept, while remaining queued images are not processed.

Find the output files

Sliprail leaves each source file in place and writes a separate output:

  • A standalone image is saved beside its source. For example, photo.jpg becomes photo-compressed.jpg
  • A dragged folder creates a sibling folder. For example, album becomes album-compressed
  • If that name already exists, Sliprail uses the next available suffix, such as photo-compressed-2.jpg or album-compressed-2
  • Existing files and folders are not overwritten

After the batch completes or stops, use the buttons under Output Locations to open the generated locations. The result table also provides Open Location for each output. Files are revealed in Finder or File Explorer, while folder outputs open directly.

A recompressed image is not guaranteed to be smaller. If the new encoding would be the same size or larger, Sliprail copies the original into the output path and marks the result as Unchanged.

Supported formats and file details

Image Compressor accepts these extensions:

  • JPEG: .jpg, .jpeg, and .jfif
  • PNG: .png
  • WebP: .webp
  • AVIF: .avif
  • GIF: .gif
  • JPEG XL: .jxl

The output keeps the same format as the source. Animated GIF and animated WebP files are processed with their animation preserved. SVG and other unlisted formats are not supported.

Do not rely on re-encoded outputs to retain embedded metadata such as EXIF. Sliprail applies orientation information before saving. When a file is marked Unchanged, the output is a copy of the original file instead of the re-encoded result.

Image Compressor does not provide controls for changing dimensions, converting formats, or reaching an exact KB value.