Image Processing – Photography Sepia-toning Effect

Sepia-toning effect is used very commonly in photography.It is the process of changing the intensity on every pixel color of a gray-scale image, or so-called black-and-white.

Look up the concepts of Sepia on Wikipedia.

This is the original one:

Original Image

If I try to apply the sepia effect for each color channel as majority, it results much pretty nicely 🙂

Sepia Effect: Red & Green, no Blue

When I try to increase the depth of Red & Green, it results in a brighter one.

Sepia Effect: Red & Green (increasing), no Blue

Above images applied Red as majority,now trying the rest over gray-scale image:

Sepia Effect: Green as majority

Sepia Effect: Blue as majority

This is a really really cool effect!

My implementation is simple based on its concepts:

	public static Bitmap createSepiaToningEffect(Bitmap src, int depth, double red, double green, double blue) {
		// image size
		int width = src.getWidth();
		int height = src.getHeight();
		// create output bitmap
		Bitmap bmOut = Bitmap.createBitmap(width, height, src.getConfig());
		// constant grayscale
		final double GS_RED = 0.3;
		final double GS_GREEN = 0.59;
		final double GS_BLUE = 0.11;
		// color information
		int A, R, G, B;
		int pixel;

		// 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);
				// get color on each channel
				A = Color.alpha(pixel);
				R = Color.red(pixel);
				G = Color.green(pixel);
				B = Color.blue(pixel);
				// apply grayscale sample
				B = G = R = (int)(GS_RED * R + GS_GREEN * G + GS_BLUE * B);

				// apply intensity level for sepid-toning on each channel
				R += (depth * red);
				if(R > 255) { R = 255; }

				G += (depth * green);
				if(G > 255) { G = 255; }

				B += (depth * blue);
				if(B > 255) { B = 255; }

				// set new pixel color to output image
				bmOut.setPixel(x, y, Color.argb(A, R, G, B));
			}
		}

		// return final image
		return bmOut;
	}

Hope you like it!

Cheers,
Pete Houston