Mastering OpenCV 3 - Second Edition

Generating a color painting and a cartoon

A strong Bilateral filter smoothens flat regions while keeping edges sharp; and therefore, is great as an automatic cartoonifier or painting filter, except that it is extremely slow (that is, measured in seconds or even minutes, rather than milliseconds!). Therefore, we will use some tricks to obtain a nice cartoonifier, while still running in acceptable speed. The most important trick we can use is that we can perform Bilateral filtering at a lower resolution and it will still have a similar effect as a full resolution, but run much faster. Lets reduce the total number of pixels by four (for example, half width and half height):

 Size size = srcColor.size(); Size smallSize; smallSize.width = size.width/2; ...