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image-rendering.md

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Image Rendering

fetch can render images directly in your terminal when fetching image URLs.

Image Control

--image OPTION

Control how images are rendered:

Value Description
auto Try optimal protocol, fallback to external tools (default)
native Use only built-in decoders
off Disable image rendering 
fetch --image native example.com/photo.jpg
fetch --image off example.com/image.png

Supported Image Formats

Built-in Decoders (Native)

These formats are decoded without external tools:

  • JPEG - .jpg, .jpeg
  • PNG - .png
  • TIFF - .tiff, .tif
  • WebP - .webp

With External Adapters

When --image auto (default), these additional formats are supported if you have the required tools installed:

  • AVIF - .avif
  • HEIF/HEIC - .heif, .heic
  • GIF - .gif (static frame)
  • BMP - .bmp
  • And many more...

Terminal Protocols

fetch automatically detects your terminal and uses the best available image protocol.

Kitty Graphics Protocol

Supported terminals: Kitty, Ghostty, Konsole

The highest quality protocol with full color support and efficient transmission.

iTerm2 Inline Images

Supported terminals: iTerm2, WezTerm, Hyper, Mintty

Base64-encoded PNG images displayed inline.

Unicode Block Characters

Supported terminals: All terminals

Fallback rendering using Unicode block characters (▀▄█). Works everywhere but with reduced resolution.

Terminal Detection

fetch detects your terminal emulator through environment variables:

Terminal Detection Method
Kitty KITTY_PID or TERM=xterm-kitty
Ghostty GHOSTTY_BIN_DIR or TERM=xterm-ghostty
iTerm2 ITERM_SESSION_ID or TERM_PROGRAM=iTerm.app
WezTerm WEZTERM_EXECUTABLE or TERM_PROGRAM=WezTerm
Konsole KONSOLE_VERSION
Hyper TERM_PROGRAM=Hyper
Mintty TERM_PROGRAM=mintty
VS Code TERM_PROGRAM=vscode or VSCODE_INJECTION
Windows Terminal WT_SESSION
Apple Terminal TERM_PROGRAM=Apple_Terminal
Alacritty TERM=alacritty
Zellij ZELLIJ
tmux TERM_PROGRAM=tmux

External Adapters

When native decoders can't handle an image format, fetch tries external tools in this order:

1. VIPS (vips)

Fast image processing library.

# Install on macOS
brew install vips

# Install on Ubuntu/Debian
apt install libvips-tools

2. ImageMagick (magick)

Comprehensive image manipulation tool.

# Install on macOS
brew install imagemagick

# Install on Ubuntu/Debian
apt install imagemagick

3. FFmpeg (ffmpeg)

Multimedia framework with image support.

# Install on macOS
brew install ffmpeg

# Install on Ubuntu/Debian
apt install ffmpeg

Configuration

Set image rendering preferences in your configuration file:

# Disable image rendering
image = off

# Use only native decoders
image = native

# Auto-detect (default)
image = auto

Image Sizing

Images are automatically resized to fit within 80% of the terminal height while maintaining aspect ratio. This ensures images don't overwhelm the terminal display.

Examples

View an Image

fetch example.com/photo.jpg

Download Instead of Display

fetch -o photo.jpg example.com/photo.jpg

Force Native Decoding

fetch --image native example.com/image.png

Disable Image Rendering

fetch --image off example.com/image.jpg

Troubleshooting

Image Not Displaying

  1. Check terminal support: Not all terminals support inline images
  2. Verify format: Use --image native to test if it's a format issue
  3. Install adapters: Install VIPS, ImageMagick, or FFmpeg for more formats
  4. Check terminal size: Very small terminals may not render properly

Poor Quality

  1. Use a native protocol terminal: Kitty, Ghostty, or iTerm2 provide best quality
  2. Check image dimensions: Very large images are resized
  3. Block character fallback: Quality is limited with Unicode blocks

Colors Look Wrong

  1. Terminal color support: Ensure your terminal supports 24-bit color
  2. tmux/screen: May reduce color depth
  3. Try native decoding: --image native

Image Dimensions Too Large

fetch limits images to 8192x8192 pixels maximum to prevent memory issues. Larger images will fail to decode with a "dimensions are too large" error.

Limitations

  • Animated GIFs: Only the first frame is displayed
  • Maximum size: 8192x8192 pixels
  • Memory limit: Images are loaded into memory for processing
  • Terminal multiplexers: tmux and screen may interfere with image protocols

See Also