Formats

Matrix

Format	Read (input)	Write (output)
JPEG	yes	yes
PNG	yes	yes
WebP	yes	yes
AVIF	yes	yes
GIF	yes	yes
BMP	yes	yes
TIFF	yes	no

Set the output format with the format option (or --format on the CLI). If you do not set it, the output keeps the input format.

# PNG in, WebP out, lossless
dusimagez compress in.png out.webp --format webp --lossless

# Any input, JPEG out at quality 80
dusimagez compress in.png out.jpg --format jpeg

v0.1.0 limits — stated plainly

• No HEIC. Reading or writing HEIC is not supported in v0.1.0 (libheif + licence). An HEIC input fails with UNSUPPORTED_FORMAT.
• AVIF encode is lossy-only / 8-bit. This is a limit of the underlying encoder crate, not a choice: no lossless AVIF, no 10-bit AVIF in v0.1.0. AVIF decoding is unaffected.
• GIF encode is first-frame only. An animated GIF input compresses to a still GIF of its first frame. Animation is not preserved.
• TIFF is input-only. You can compress a TIFF by converting it to another format (--format jpeg, for example), but dusimagez cannot write TIFF in v0.1.0.
• Whole image in memory. There is no streaming mode; a very large image is refused by the max_pixels / max_dimension limits (IMAGE_TOO_LARGE) rather than being processed in chunks.

Format notes

• JPEG — the workhorse. Quality, subsampling, progressive and target-size search all apply. No transparency: converting a transparent PNG to JPEG drops the alpha channel.
• PNG — lossless by nature. Controlled by png_compression_level (0–9) and palette (quantise to 256 colours), not by quality. progressive means interlaced PNG.
• WebP — lossy or lossless (lossless: true), with effort 0–6. The best all-round choice when you control both ends.
• AVIF — the smallest lossy files in v0.1.0, at the cost of slower encoding (effort is the AVIF speed, 0–10). Lossy / 8-bit only.
• GIF — for simple graphics. First frame only on output.
• BMP — uncompressed output; useful as a compatibility target, not for saving space.