Compress Images on Mac

Lossy vs lossless

TinyOwl’s built-in levels—Balanced Q75, Smaller Q60, and Smallest Q50—are quality settings, not a separate lossless switch.

• JPEG and AVIF exports at these levels are lossy. Use them when a smaller file matters more than a bit-identical image.
• WebP at the built-in levels is also lossy. It is a common choice for blogs and docs when the destination accepts WebP.
• PNG at Balanced Q75 stays closer to a lossless rewrite. Q60 and Q50 may reduce colors to shrink the file, which is more noticeable on photos than on flat UI screenshots.
• Keep original format still applies the selected level to whatever the source is. A camera JPEG will not become lossless PNG just because you chose a cautious quality number.

Supported input and export formats are PNG, JPG/JPEG, WebP, BMP, TIFF, and AVIF. HEIC is not supported. Test with Save as on a few of your own files before overwriting a folder.

Edit a Compression Preset

Use this path when you want to change output format, compression level, save mode, or compressed filenames.

1. Open Settings.
2. Select Compression Presets in the settings navigation.
3. Click Edit on an existing preset, or click Add preset to create one.
4. Change the preset name if needed.
5. Update the fields you need.
6. Return to Settings -> Workflows if a workflow should use this preset.

Preset Fields

• Output format: keep the original format or export as AVIF, BMP, PNG, JPG, TIFF, or WebP.
• Compression level: choose one of the common benchmark-aligned levels: Balanced Q75, Smaller Q60, or Smallest Q50. The same level can map to different encoder behavior depending on the output format.
• Output mode: choose Save as to write a new file, or Overwrite original to replace the source file.
• Filename strategy: keep the original name, add a suffix, use a timestamp, or use a random name.
• Filename suffix: used when the filename strategy is suffix-based.
• Output folder: used by save-as presets so repeated runs can save automatically.

Use a Compression Preset in a Workflow

Editing a compression preset does not automatically select it for every workflow. If the workflow also changes dimensions first, configure that separately in Resize Presets.

1. Open Settings -> Workflows.
2. Expand the workflow with Edit.
3. Select the Compression step.
4. Choose the compression preset.
5. Click Use now to make it the active workflow for both the main window and menu bar.

Built-In Compression Presets

TinyOwl includes these starting points:

• Basic - Save as: keeps the original format and writes a compressed copy.
• WebP - Save as: exports WebP copies for web use.
• High compression - Save as: keeps the original format with stronger compression.
• AVIF - Save as: exports AVIF copies for smaller files when AVIF is acceptable.
• Basic - Overwrite original: keeps the original format and replaces the source file.

Safe Rules

• Use Save as while testing.
• Give overwrite presets obvious names.
• Test compression levels on representative images before running a large batch.
• Keep one preset per repeated output goal, such as “WebP Q75” or “Archive AVIF Q50”.
• After creating a preset, attach it from Workflows rather than expecting existing workflows to change automatically.
• If you are choosing between a browser compressor and a local Mac app, start with TinyOwl vs TinyPNG. For another local optimizer, see TinyOwl vs ImageOptim.