Color Matrix
Consider the following matrix. This matrix is used as a transformation matrix, or color matrix, since this is used to change the colors of the given image.
[ a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t ]
If RGBA are the values of a pixel for a given image, then the resulting pixel R’G’B’A’ is given by the following formula.
R' = a*R + b*G + c*B + d*A + e; G' = f*R + g*G + h*B + i*A + j; B' = k*R + l*G + m*B + n*A + o; A' = p*R + q*G + r*B + s*A + t;
In terms of matrix multiplication, the relation is given by
Please note that we provide the color matrix as a one dimensional matrix. In the above picture, we have given a 2D matrix only for understanding the transformation.
Uses of Color Matrix
Color matrix can be used to apply a filter, or transform, a given image.
For example, some of the operations that we can do on an image using color matrix are
- Invert colors of an image
- Display only red color channel of an image
- Adjust brightness of an image
- Adjust contrast of an image
Tutorials using Color Matrix
The following tutorials cover some of the scenarios where we use a color matrix to transform a given image.