Image Contrast android

From the original image:

Original Image

I take contrast on this image:

Contrast = 100

Contrast = 50

First, calculate the contrast value: contrast = ((value + 100) / 100) ^ 2 (square by 2, or power 2).

Then do this for each color channel:

+ Take pixel color divided by 255

+ Minus 0.5

+ Multiply contrast value calculated above.

+ Plus 0.5

+ Multiply by 255

Here the implementation:

public static Bitmap createContrast(Bitmap src, double value) { // image size int width = src.getWidth(); int height = src.getHeight(); // create output bitmap Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig()); // color information int A, R, G, B; int pixel; // get contrast value double contrast = Math.pow((100 + value) / 100, 2); // scan through all pixels for(int x = 0; x < width; ++x) { for(int y = 0; y < height; ++y) { // get pixel color pixel = src.getPixel(x, y); A = Color.alpha(pixel); // apply filter contrast for every channel R, G, B R = Color.red(pixel); R = (int)(((((R / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(R < 0) { R = 0; } else if(R > 255) { R = 255; } G = Color.red(pixel); G = (int)(((((G / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(G < 0) { G = 0; } else if(G > 255) { G = 255; } B = Color.red(pixel); B = (int)(((((B / 255.0) - 0.5) * contrast) + 0.5) * 255.0); if(B < 0) { B = 0; } else if(B > 255) { B = 255; } // set new pixel color to output bitmap bmOut.setPixel(x, y, Color.argb(A, R, G, B)); } } // return final image return bmOut; }

Hope you enjoy it!