Blending and Overlays

Both the inside and outside color schemes allow for both blending and overlays of coloring methods. This is a low-level layering technique that is more convenient then a full featured layer setup, but also not as versitile. If you need something more sophisticated you should save several coloring method images and use a tool like PhotoShop, or my favorite, Gimp to compose the final image.

In the blending mode simply check the methods you wish to blend together and give each a percentage for blending. The program will take each selected method and pixel by pixel determine each methods color, take the respective percentage of the method and add the colors together. If a color channel exceeds its maximum then it is trimmed to its maximum. You can set the percentages to add up to more than 100 (or less than 100). If a color becomes too bright, it is trimmed at white.

The overlay mode allows you to select a top method and a bottom method. Pixel by pixel, it will take the top method, calculate the pixel's brightness, b, and create the color c = top * b + bottom * (1 - b) for the pixel. There is an option to invert the brightness which replaces b by 1 - b in the above equation.

With an overlay, you want the top image to be black where you want the bottom image to show through and bright where you want the top image to overwrite the bottom. If you want a dark color to overlay the bottom then invert the brightness and use white where you want the bottom image to show through.

Top Image


Bottom Image


Combined image using the overlay.


Same two images blended at 75% each.