Support
Everything you need to know about Outer. Can't find your answer? Email [email protected].
Getting started
- Drag a folder of images onto Outer — or use File → Open Folder.
- Outer detects each image's content edges and shows a live preview.
- Tweak the threshold, padding, or resize options in the sidebar.
- Pick an export folder and hit Export.
By default, Outer writes processed files to a new folder. Your originals are left untouched unless you turn on Replace Original.
Supported formats
Input
PNG, JPEG, WebP, HEIC, TIFF, SVG.
Output
PNG, JPEG, TIFF, HEIC, AVIF — or preserve the original format. SVGs stay vector when output as SVG; exporting an SVG to a raster format renders it at the output size (never upscaled from a thumbnail). WebP is read-only: macOS can decode it but has no encoder, so WebP sources export as PNG. Animated sheets export as GIF, APNG, MP4 or Lottie (see Multi Mode below).
Settings guide
Threshold
Controls how aggressively Outer trims. Default is 15 (range 0–254). Lower values trim tighter; higher values are more forgiving. For JPEGs with compression artifacts, try 10–30.
Padding
Add space back after trimming.
- Pixels: −500 to +500 px. Negative values trim further in.
- Percent: 0–50% of the shorter side. Default 5%.
- Uniform padding (when resize is on): applies padding after resize so every exported image has identical spacing around the subject. This is how you get batches that line up perfectly.
Center by
How the subject sits inside its padding. Edges centers the pixel bounding box. Mass centers the shape's center of mass, and Contrast weights bold, high-contrast areas more — closest to how the eye judges balance; a Balance slider sets how far to go. Manual gives you sliders, and the arrow keys nudge in the preview (⇧ for bigger steps). Turn on Centre in the preview's bottom bar for a crosshair.
Remove background
- Colour — keys pixels close to the background color detected from the edges. Best for flat art and scans.
- Object Size — keeps only shapes above a size; drops the background and stray bits.
- Subject (AI) — macOS's on-device subject detection, for photos on busy backgrounds.
- Clean edges — edge pixels are re-read as partial coverage of the line beside them, so outlines lose their light halo and pencil strokes stay soft. Edge width sets how far in that reaches; Shrink edge chokes anything left.
- Corner cleanup — clears the tiny pockets of background a key leaves where strokes meet.
- Regions tool (preview bottom bar) — click an enclosed gap to remove it, drag to brush away leftovers, ⌥-drag to restore. In Subject mode a click removes a piece the detector got wrong.
Detached pieces
Drop detached pieces removes separate shapes up to a size — specks, sparks, stray bits — from any source; Keep only the largest shape is the blunt version. The opposite of Multi Mode's fragment attachment.
Multi Mode
Detects every separate shape on a sheet and exports each as its own file — trim, padding, resize and centering apply per shape. Attach small fragments keeps sparks and drips with their subject; Clean cuts masks neighbours. Rebuild as sheet lays the frames back out in equal cells (largest frame or a fixed size, columns auto or set) in the order you choose. The preview's Animate tab steps through frames with onion skinning, a timeline to reorder, zoom controls (fit, 1:1, steps — SVG sources are redrawn from the vector at any zoom, so they stay crisp), and per-frame nudges by drag or arrow keys; Nudge limit decides whether a frame may use its padding, must keep its padding inside the cell, or has no limit. Export the sheet with a JSON atlas, plus GIF, APNG, MP4 (H.264) or Lottie (image sequence) at the frame delay you set.
Resize
- Percentage (10–400%)
- Fixed width or fixed height — aspect ratio maintained by default
- Fixed dimensions — set both; the subject is fitted and centered inside the canvas, never stretched
Rename
Add a prefix (default processed_) or suffix (default
_trimmed), and optionally change case:
lowercase, UPPERCASE, kebab-case, snake_case, camelCase, or
PascalCase.
Keyboard shortcuts
- ⌘OOpen folder
- ⌘⇧OAdd files
- ⌘ASelect all images
- ⌘DDeselect all
- ⌘⌫Remove selected
- ⌘↩Process selected
- ⌘EExport
- ← → ↑ ↓Nudge the shape (Manual centering) or the current frame (Animate); ⇧ for bigger steps
- , .Previous / next frame in Animate
- spacePlay / pause in Animate
FAQ
My images don't have transparent backgrounds. Does Outer still work?
Yes. When there's no transparency, Outer samples the edge pixels to detect the background color and trims based on that. If the background is noisy (like a JPEG with compression), bump the threshold up.
Will my original files be changed?
No, not unless you explicitly turn on Replace Original. By default Outer writes processed copies to a new export folder. Even so, always back up important images before large batch operations.
How do I make every image have identical padding?
Turn on resize (to a fixed width, height, or dimensions) and enable Uniform padding. The padding is applied after resize, so every image ends up with the exact same space around the subject.
What happens to SVGs?
When the output format is SVG (or "preserve original"),
Outer adjusts the SVG's viewBox without
rasterizing — you keep full vector quality. If you export an
SVG to PNG/JPEG/TIFF, Outer rasterizes it and shows a
warning first.
How big of a batch can I run?
Outer processes images in chunks and uses a disk-backed cache to keep memory usage low, so batches of thousands are fine as long as you have disk space. Files are processed 100 at a time to keep the UI responsive.
What if one file fails to process?
The batch keeps going. Outer counts the failures and shows a summary at the end (for example: "Processed 982 images with 3 errors"). The failed files are left untouched.
Does Outer support RAW, PDF, or animated GIFs?
RAW and PDF: no. Animated GIF, APNG, MP4 and Lottie: as output from Multi Mode's rebuilt sheets — one cell per frame. Inputs are PNG, JPEG, WebP, HEIC, TIFF, or SVG.
Are my images sent anywhere?
No. Outer runs entirely on your Mac. Nothing is uploaded. See the privacy policy for details.
Troubleshooting
If you see one of these messages:
- "Failed to load image" — the file is likely corrupted or an unsupported variant. Try opening it in Preview to confirm it reads.
- "N files have outdated settings" — you changed a setting after processing. Re-process before export.
- "JPEG does not support transparency" — heads up that trimmed edges will be filled when exporting to JPEG. Use PNG or TIFF to preserve transparency.
- "Original files will be overwritten" — you have Replace Original on. Turn it off or make sure you have backups.
Still stuck?
Email [email protected] with a description of the issue and, if relevant, an example image. We read every message.