convertImage

Convert images between popular raster formats.

Usage

openGyver convertImage <image> [flags]

Arguments

Argument	Required	Description
image	Yes	Path to the input image file

Flags

Flag	Short	Type	Default	Description
--output	-o	string	""	Output file path (required)
--quality		int	90	JPEG quality 1-100 (ignored for other formats)
--width		int	0	Resize to this width in pixels (0 = keep original)
--height		int	0	Resize to this height in pixels (0 = keep original)
--format	-f	string	""	Override input format detection (png, jpeg, gif, bmp, tiff, webp, raw)
--quiet	-q	bool	false	Suppress output messages (for piping)
--json	-j	bool	false	Output result as JSON
--help	-h	bool	false	Show help for convertImage

Supported Formats

Native Go Formats

Format	Read	Write	Extensions
PNG	Yes	Yes	.png
JPEG	Yes	Yes	.jpg, .jpeg, .jfif, .jpe
GIF	Yes	Yes	.gif (first frame)
BMP	Yes	Yes	.bmp
TIFF	Yes	Yes	.tiff, .tif
WebP	Yes	No*	.webp
PPM	Yes	Yes	.ppm, .pgm, .pbm, .pnm
PCX	Yes	No	.pcx
TGA	Yes	No	.tga
SVG	No	Yes*	.svg (raster to vector via potrace/ImageMagick)
ICO	No	No	.ico (use toIco command instead)

External Tool Formats

Format	Extensions	Requirements
HEIC	.heic, .heif	dcraw, ImageMagick, or Apple sips
Camera RAW	.cr2, .cr3, .crw, .nef, .arw, .dng, .orf, .raf, .rw2, .pef, .erf, .mrw, .srf, .sr2, .3fr, .k25, .kdc, .mef, .nrw, .x3f, .dcr, .mos, .iiq, .raw	dcraw, ImageMagick, or Apple sips

* WebP can be decoded (read) but not encoded (write) in pure Go. SVG writing uses potrace or ImageMagick for raster-to-vector tracing.

Resize Behavior

• If only --width is set, height scales proportionally to maintain aspect ratio.
• If only --height is set, width scales proportionally to maintain aspect ratio.
• If both are set, the image is resized to the exact dimensions (may change aspect ratio).
• If neither is set (both 0), the original dimensions are kept.
• Resizing uses nearest-neighbor interpolation.

Examples

# Convert PNG to JPEG
openGyver convertImage photo.png -o photo.jpg

# Convert JPEG to PNG
openGyver convertImage photo.jpg -o photo.png

# Convert JPEG to BMP
openGyver convertImage photo.jpg -o photo.bmp

# Convert BMP to TIFF
openGyver convertImage photo.bmp -o photo.tiff

# Convert WebP to PNG (WebP decode supported)
openGyver convertImage photo.webp -o photo.png

# Convert with custom JPEG quality
openGyver convertImage photo.png -o photo.jpg --quality 85

# Create a thumbnail (width only, height auto-calculated)
openGyver convertImage photo.png -o thumb.jpg --width 200

# Resize to exact dimensions
openGyver convertImage photo.png -o resized.png --width 800 --height 600

# Override input format detection
openGyver convertImage raw.dat -o out.png --format bmp

# Quiet mode for scripting
openGyver convertImage photo.png -o photo.jpg -q

# JSON output for automation
openGyver convertImage photo.png -o photo.jpg -j

# Convert RAW camera file (requires dcraw or ImageMagick)
openGyver convertImage photo.cr2 -o photo.png

# Convert HEIC to JPEG (requires sips on macOS)
openGyver convertImage photo.heic -o photo.jpg

# Batch convert with a shell loop
for f in *.png; do openGyver convertImage "$f" -o "${f%.png}.jpg" -q; done

# Resize and convert in one step
openGyver convertImage photo.png -o thumb.jpg --width 150 --quality 75

# Pipe JSON to check dimensions
openGyver convertImage photo.png -o photo.jpg -j | jq '{width, height}'

# Convert to PPM format
openGyver convertImage photo.png -o photo.ppm

# Trace raster to SVG (requires potrace or ImageMagick)
openGyver convertImage logo.png -o logo.svg

JSON Output Format

{
  "success": true,
  "input": "photo.png",
  "output": "photo.jpg",
  "input_format": "png",
  "output_format": "jpeg",
  "width": 1920,
  "height": 1080
}

Notes

• The input format is auto-detected from the file header (magic bytes), not the extension.
• The output format is determined by the --output file extension.
• Use --format to override input format detection when auto-detection fails.
• JPEG quality is only relevant for JPEG output; it is ignored for all other formats.
• WebP encoding is not supported in pure Go. Use cwebp as a workaround: convert to PNG first, then run cwebp temp.png -o output.webp.
• HEIC encoding is not supported in pure Go. On macOS, use sips -s format heic input.png --out output.heic.
• For ICO output, use the separate toIco command.
• Camera RAW decoding tries dcraw first, then ImageMagick (magick or convert), then Apple sips on macOS.