cjxl 命令

常用示例

说明

cjxl is the reference encoder for JPEG XL, a next-generation image format designed to replace both JPEG and PNG. It is part of the libjxl project maintained by the JPEG committee. JPEG XL offers superior compression compared to legacy formats, supporting both lossy and lossless modes. A unique feature is the ability to losslessly transcode existing JPEG files, reducing their size by approximately 20% while allowing perfect reconstruction of the original JPEG. The encoder supports a wide range of input formats including PNG, APNG, GIF, JPEG, PPM, and PFM. It handles high bit depths, HDR content, and animations natively. The effort parameter provides a trade-off between encoding speed and compression ratio.

参数

-q _N_, --quality=_N_

Quality setting from 1 to 100. 100 is mathematically lossless. Default is 90.

-d _N_, --distance=_N_

Target visual distance (0=lossless, 1.0=visually lossless, higher means more compression). Overrides quality.

-e _N_, --effort=_N_

Encoder effort level from 1 to 9. Higher values produce smaller files but encode slower. Default is 7.

--lossless_jpeg=_N_

When encoding JPEG input, 1 preserves the original JPEG data for bit-exact reconstruction.

-j, --jpeg_transcode

Lossless JPEG transcode mode (shortcut for --lossless_jpeg=1).

--num_threads=_N_

Number of threads to use. 0 means use all available cores.

--progressive

Enable progressive decoding for the output file.

--premultiply=_N_

Premultiply alpha channel (0=no, 1=yes, -1=auto).

-h, --help

Display help information and exit.

-v, --verbose

Enable verbose output.