node-bitmap-color-transform

Performs color transformations on bitmap images using node buffers. Currently supports Windows and OS/2 .bmp files with header types of BM and BA. Available transforms are an rgb diff in the form of (30,-20,50) and color inversion. Support for more transforms like greyscale are planned.

CLI

Perform an rgb transform on a file named test.bmp and output to transformed.bmp:

bmptransform test.bmp "-t=(40,12,-60)" -o=transformed.bmp

Perform a color inversion on toinvert.bmp:

bmptransform toinvert.bmp -t=invert -o=inverted.bmp

If no output location is specified it will write file named transformed.bmp to your current working directory.

API

bitmapTransformer(buffer, transform):

buffer is the bitmap as read from disk and transform can either be a string ('invert') or an object of rgb diffs ({r: 30, g: -40, b: 60}).

Output is a new, transformed buffer. The original is not mutated.

const fs = require('fs');
const bitmapTransformer = require('bmp-transform');

fs.readFile('test.bmp', (err, data) => {
  if (err) return console.log(err);

  const transformed = bitmapTransformer(data);

  fs.writeFile('output.bmp', transformed, err => return console.log(err));
});

Known issues

Bitmaps with color depth other than 24 bit or alpha channels are not correctly processed.

License

This software is licensed under the terms of the MIT license.