Adjusting color temperature on ImageView

1
votes

I successfully implemented functionality to adjust the contrast and/or brightness of an ImageView via values coming from user's SeekBars selections. For the contrast it looks like that (similar for brightness):

// Contrast
ColorMatrix colorMatrix = new ColorMatrix();
colorMatrix.set(new float[] {
        scale, 0, 0, 0, translate,   // Red
        0, scale, 0, 0, translate,   // Green
        0, 0, scale, 0, translate,   // Blue
        0, 0, 0, 1, 0 });            // Alpha

imageView.setColorFilter(new ColorMatrixColorFilter(colorMatrix);

So I could adjust the contrast and/or brightness just by scaling (multiplication) or translating (addition) the RGB values with another value.

How can I do the same thing (using a matrix) for adjusting the image's color temperature?

2
androidimage-processingcolormatrix

2 Answers

2
votes

I just created such a Matrix for my application to adjust the color temperature.

ColorMatrix colorMatrix = new ColorMatrix();

colorMatrix.set(new float[] {
RED/255.0f, 0, 0, 0, 0,
0, GREEN/255.0f, 0, 0, 0
0, 0, BLUE/255.0f, 0, 0,
0, 0, 0, 1, 0}); 
imageView.setColorFilter(new ColorMatrixColorFilter(colorMatrix);

The values for RED, GREEN and BLUE you can get for example from here: http://www.vendian.org/mncharity/dir3/blackbody/UnstableURLs/bbr_color.html

It works perfectly fine and even images with a very strong color temperature can be adjusted accordingly :)

0
votes

I followed destiny answer, but had to do some adjustment, here is how i did it:

let amount = 255;
let value  = 0;

(1.0000* amount)/255.0, 0, 0, 0, 0,
0, ((1.0000+value)* amount)/255.0, 0, 0, 0,
0, 0, ((1.0000+value)* amount)/255.0, 0, 0,
0, 0, 0, 1, 0