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CaesiumCLT Usage

Options

Compression (at least one is required)
  • -q, --quality <QUALITY>
    Sets compression quality between 0 and 100. Higher the value, better the quality and bigger the file size.
  • --lossless
    Perform lossless compression. Some file formats may not support this or result in bigger file sizes.
  • --max-size <MAX_SIZE>
    Attempts to compress the image to the nearest size in bytes without exceeding it. If the requested size is too small, it will output the smallest possible result.
Advanced compression

  • --jpeg-chroma-subsampling <JPEG_CHROMA_SUBSAMPLING>
    Sets the chroma subsampling for JPEG files. Possible values are:

    • 4:4:4
    • 4:2:2
    • 4:2:0
    • 4:1:1
    • auto

  • --jpeg-baseline
    Forces the output to be in baseline JPEG format instead of progressive.

  • --png-opt-level <PNG_OPT_LEVEL>
    Sets the optimization level for PNG files. Higher values result in better compression but take longer to complete. Possible values are between 0 and 6. Default is 3.

  • --zopfli
    Use zopfli when optimizing PNG files. It may take a very long time to complete, especially if the application is not build in release mode.

Metadata
  • -e, --exif
    Keeps EXIF metadata info during compression, if present. This can slightly increase the output file size.
  • --keep-dates
    Keeps the original last modified and last accessed date information, if possible.
  • --strip-icc
    Strips all ICC profile information on JPG, regardless of -e flag.
Resizing
  • --width <WIDTH>
    Sets the width of the output image. If height is not set, it will preserve the aspect ratio. Can't be used with --long-edge or --short-edge.
  • --height <HEIGHT>
    Sets the height of the output image. If width is not set, it will preserve the aspect ratio. Can't be used with --long-edge or --short-edge.
  • --long-edge <LONG_EDGE>
    Sets the size of the longest edge of the image. It is aware of rotation metadata. Can't be used with --width or --height or --short-edge.
  • --short-edge <SHORT_EDGE>
    Sets the size of the shortest edge of the image. It is aware of rotation metadata. Can't be used with --width or --height or --long-edge.
  • `--no-upscale Prevent upscaling the image when resizing
Destination
  • -o, --output <OUTPUT>
    Sets the output folder. If the folder does not exist, it will be created. Can't be used with --same-folder-as-input.
  • --same-folder-as-input
    Sets the output folder to be the same as the input folder. WARNING: this can potentially overwrite the original files if a suffix is not set. Overwritten files CANNOT be recovered.
  • --suffix <SUFFIX>
    Adds a suffix to the output filename, before the file extension.
  • -S, --keep-structure
    Preserves the folder tree structure of the input files. Can be used only with -R.
  • -O, --overwrite <OVERWRITE>
    Sets the overwrite policy if the output file already exists. Possible values are:
    • all: Always overwrite
    • never: Never overwrite
    • bigger: Overwrite only if the file to be overwritten is bigger
  • --min-savings <MIN_SAVINGS>
    Skip writing the output file if the compression savings are below the specified threshold. This is useful to prevent repeated re-compression from degrading image quality.
    Supported formats:
    • Percentage (supports decimals): 10%, 1.5%, 0.1%
    • Size with unit: 100KB, 1MB, 500KiB
    • Plain number (interpreted as bytes): 1000, 50000
  • --format <FORMAT>
    Converts the original image to the selected format. Possible values are:
    • jpeg
    • png
    • webp
    • original (default, no changes)
Other
  • -R, --recursive
    If the input is a folder, scan its subfolders too.
  • -d, --dry-run
    Do not write output files, only simulate the process.
  • --threads <THREADS>
    Specify the number of parallel jobs. The maximum is the number of processors available. 0 means that the application will try to guess the maximum number of parallel jobs available. Default is 0.
  • --check-extension-only Trust file extensions instead of reading magic bytes. This is significantly faster when scanning large directories containing many non-image files, but it will skip valid image files that do not have file extensions.
  • -Q, --quiet
    Suppress all output. Overrides --verbose.
  • --verbose <VERBOSE>
    Select how much output you want to see. Possible values are:
    • 0: Suppress all output
    • 1: Show only progress and final results
    • 2: Show also skipped and error messages
    • 3: Print all
  • --json
    Output results as structured JSON to stdout. Progress is written to stderr so the JSON can be piped directly. Cannot be used with --quiet or --verbose.
  • -h, --help
    Print help. A summary can be seen with -h.
  • -V, --version
    Print version.

Full help

Use --help to see the full list of options.