image-converter

name

image-converter

description

Convert images between common formats on macOS, especially SVG/PNG/ICO/ICNS/JPEG/WebP/PDF, using installed local tools such as ImageMagick, rsvg-convert, sips, qlmanage, and iconutil. Use when the user asks to convert image files, generate favicon/icon assets, rasterize SVGs, create Windows .ico files, create macOS .icns files, resize during conversion, or inspect available image conversion commands.

Image Converter

Use this skill for local image format conversion on macOS.

Tool preference

Prefer tools in this order:

1. rsvg-convert for SVG to PNG when available. It gives predictable SVG rasterization.
2. magick for most conversions and for multi-size .ico.
3. sips for simple macOS-native PNG/JPEG/TIFF conversions and resizing.
4. iconutil for .iconset to .icns.
5. qlmanage -t only as a fallback preview renderer when SVG/PDF conversion tools fail.

Common macOS tool locations include:

• /opt/homebrew/bin/rsvg-convert
• /opt/homebrew/bin/magick
• /usr/bin/sips
• /usr/bin/iconutil
• /usr/bin/qlmanage

Use command -v at runtime instead of hardcoding paths unless a command lookup fails.

Quick workflow

1. Inspect the input:

   file input.svg
   magick identify input.svg
   

   If magick identify cannot read the file, use file only and continue with format-specific tools.

2. Convert with the bundled script when possible:

   skills/image-converter/scripts/convert-image.sh input.svg output.png --size 800
   skills/image-converter/scripts/convert-image.sh input.svg output.ico
   skills/image-converter/scripts/convert-image.sh input.png output.icns
   

3. Verify output:

   file output.png output.ico
   magick identify output.png output.ico
   

Format notes

• SVG to PNG: preserve transparency with rsvg-convert or magick -background none.
• SVG/PNG to ICO: create a multi-resolution icon containing 256,128,64,48,32,16.
• PNG to ICNS: create an .iconset with 16, 32, 64, 128, 256, 512, and 1024 pixel variants, then run iconutil -c icns.
• JPEG output has no alpha channel. If converting transparent input to JPEG, flatten onto white unless the user specifies a background.
• Do not overwrite source files unless the user explicitly asks. Same-stem outputs such as icon.svg -> icon.png are fine.

Guardrails

• Never overwrite source files unless the user explicitly asks.
• Never assume a tool is installed — check with command -v at runtime before using it.
• When all conversion tools are missing, report which tools are needed and stop; do not silently fall back to a different output format.
• For ICO/ICNS generation, always verify the output contains the expected sizes before reporting success.

Common commands

SVG to PNG:

rsvg-convert -w 800 -h 800 icon.svg -o icon.png

SVG/PNG to multi-size ICO:

magick icon.svg -background none -define icon:auto-resize=256,128,64,48,32,16 icon.ico

PNG/JPEG resize:

sips -Z 1024 input.png --out output.png

PNG to ICNS:

mkdir -p AppIcon.iconset
sips -z 16 16 input.png --out AppIcon.iconset/icon_16x16.png
sips -z 32 32 input.png --out AppIcon.iconset/[e-mail]
sips -z 32 32 input.png --out AppIcon.iconset/icon_32x32.png
sips -z 64 64 input.png --out AppIcon.iconset/[e-mail]
sips -z 128 128 input.png --out AppIcon.iconset/icon_128x128.png
sips -z 256 256 input.png --out AppIcon.iconset/[e-mail]
sips -z 256 256 input.png --out AppIcon.iconset/icon_256x256.png
sips -z 512 512 input.png --out AppIcon.iconset/[e-mail]
sips -z 512 512 input.png --out AppIcon.iconset/icon_512x512.png
sips -z 1024 1024 input.png --out AppIcon.iconset/[e-mail]
iconutil -c icns AppIcon.iconset -o AppIcon.icns