Compression Engine EN

Compression Engine

The compression engine lives in zipax-cross/crates/zipax-core and is the heart of the project, shared by the desktop app and the CLI.

Supported Formats

Format	Encoder	Notes
JPEG	mozjpeg	High-quality JPEG compression
PNG	oxipng + imagequant	Lossless optimization + palette quantization
WebP	webp crate	Lossy / lossless
AVIF	ravif (RAV1E)	Next-gen high-efficiency format
HEIC	libheif-rs	Read HEIC and transcode (embedded libheif)
TIFF	image crate	Read support
GIF	image crate	Read support
PDF	Ghostscript (external process)	Compress PDFs, see Ghostscript-Install-EN

Note: HEIC requires the libde265 system library; deb/rpm packages declare the libde265-0 / libde265 dependency.

Compression Modes (CompressionMode)

Mode	key	Default level	Notes
Quality first	quality	L1	Prioritize visual quality
Balanced	balanced	L3	Balance quality and size (default)
Size first	size	L6	Prioritize small size
Advanced	advanced	L3	Manual quality control
Target size	target / target_size	L3	Compress to a target size (e.g. 500KB)

Quality Levels (QualityLevel)

6 levels (L1 highest → L6 lowest), mapped to 0.0–1.0 quality floats:

Level	Quality
L1	0.95
L2	0.88
L3	0.80
L4	0.70
L5	0.60
L6	0.50

Compression Planning (plan)

plan_compression produces a CompressionPlan before execution:

• Estimates output size and savings
• Iteratively approaches the target KB in target-size mode
• Frontend shows "estimated savings" based on the plan
• Detects previously-compressed markers to skip files

Workflow Options

• Overwrite original: write directly to the original path
• Skip compressed files: recognize prior compression markers
• Copy after compression: output to a directory and keep the original
• Preserve metadata: keep EXIF and other metadata where possible
• Resize limits: max-width / max-height constrain the output size

Batch Processing

process.rs supports compressing multiple files at once (desktop compress_batch, CLI multi-file args). Combined with notify, folder automation adds newly added files to the queue automatically.

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