brdiff

Subtract two images to create a new blue-red difference image.

Pixels will appear blue in places where the first image's luminance was greater than the second, and will appear red when the opposite holds true. If the subtracted pixels are close or equal in value, the resulting pixel will approach black.

Such an image subtraction function may be useful when performing multispectral image subtraction to help emphasize areas of an object containing a specific material. Unlike a normal differencing function (resulting in a greyscale output), a blue-red difference will distinguish positive signals (blue) from the inverse (red).

Installing

First ensure that Rust is installed by following these instructions.

Then, run the following command:

cargo install brdiff

Without Cargo/Rust:

You may also grab the latest release from here run it manually.

(With this method, you will need to call the command via ./brdiff instead of brdiff, unless you also add its location to your $PATH.)

Usage

To generate a blue-red difference image from two input images, enter this command, substituting the three arguments with file names:

$ ./brdiff --help usage: brdiff <base_image> <subtracted_image> <difference_image>

Supported input and output formats include BMP, PPM, JPG/JPEG, and TIF/TIFF.

Here is an example command using .tif files:

./brdiff image_735nm.tif image_660nm.tif image_br.tif

You may even mix and match different file types (an experimental feature!):

./brdiff image_735nm.jpg image_660nm.bmp image_br.tif

The output image will be overwritten if it already exists, so be careful, and keep backups.

Contributing