Basic Black and White Algorithms

There are lots of different ways of converting a color image to Black and White, but, once you understand the basic idea, it gets simpler from there. The short version is that in a color image, there are different RGB (Red,Green,Blue) values for each pixel, while in a B&W image the RGB values for each pixel are the same.

For example, the RGB values for a pixel in a color image might be 200,100,50 and if one was to convert it to a red channel B&W, you would set the values of the pixel to 200,200,200.

Some of the simpler B&W algorithms include,

• Red channel -> Set the blue and green pixels to match the red pixels
• Blue channel -> Set the red and green pixels to match the blue pixels
• Green channel -> Set the blue and red pixels to match the green pixels
• Maximum -> Set the values of the pixel to match the largest value
• Minimum -> Set the values of the pixel to match the smallest value

When working with bitmap files a black and white pixel has only 256 possible values while a color pixel has  16777216 possible values. A single pixel in a color bitmap file takes 3 bytes to store while a single pixel in a black and white bitmap file plus 1024 bytes for the color map.