eqlm

Eqlm

Simple CLI tool to spatially equalize image luminance, lightness, saturation, or brightness

Examples

$ eqlm images/macaron.jpg -n 3 2 -t 0.8 -c

Source	Result

$ eqlm images/mayuno.jpg -n 16 2 -t 0.7 -c -i makima

Source	Result

$ eqlm images/yaesu-wall.jpg -m lightness -t 0.9 -n 9 6

Source	Result

$ eqlm images/hakone.jpg -m saturation -t 0.2 --clamp

Source	Result

Install

pip3 install eqlm

Usage

The main program can be invoked either through the eqlm command or through the Python main module option python3 -m eqlm.

usage: eqlm [-h] [-v] [-m {luminance,brightness,saturation,lightness}]
            [-n M N] [-i {linear,cubic,akima,makima}] [-t RATE]
            [-c] [-e] [-u] [-g [GAMMA]] [-d {8,16}] [-s] [-x]
            IN_FILE [OUT_FILE]

Options

positional arguments:
  IN_FILE               input image file path (use '-' for stdin)
  OUT_FILE              output PNG image file path (use '-' for stdout)
                        (default: Auto)

options:
  -h, --help            show this help message and exit
  -v, --version         show program's version number and exit
  -m {luminance,brightness,saturation,lightness}
  --mode {luminance,brightness,saturation,lightness}
                        processing mode (default: luminance)
  -n M N, --divide M N  divide image into MxN (Horizontal x Vertical) blocks
                        for aggregation (default: (2, 2))
  -i {linear,cubic,akima,makima}, --interpolation {linear,cubic,akima,makima}
                        interpolation method (linear: Linear, cubic: CubicSpline,
                        akima: AkimaSpline, makima: ModifiedAkimaSpline)
                        (default: linear)
  -t RATE, --target RATE
                        set the target rate for the output level, ranging from
                        0.0 (minimum) to 1.0 (maximum) (default: Average)
  -c, --clamp           clamp the level values in extrapolated boundaries
                        (default: False)
  -e, --median          aggregate each block using median instead of mean
                        (default: False)
  -u, --unweighted      disable weighting based on the alpha channel
                        (default: False)
  -g [GAMMA], --gamma [GAMMA]
                        apply inverse gamma correction before process
                        [GAMMA=2.2] (default: None)
  -d {8,16}, --depth {8,16}
                        bit depth of the output PNG image (default: 8)
  -s, --slow            use the highest PNG compression level (default: False)
  -x, --no-orientation  ignore the Exif orientation metadata (default: False)

License

GNU Affero General Public License v3.0 or later

Copyright (C) 2025 curegit

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.