Lighting #2

We now proceed with a common lighting technique that will level the intensity of all pixels within an image. We will use one of the images to illustrate the process.

First, we convert the image to grayscale using the Grayscale module. This essentially focuses the image into its luminance or lighting channel. This is the channel that we want to even out within the image.

Next we really REALLY blur the grayscale image using the Mean module.

From this blurred image we subtract the original color image using the Math module.

Which results in a much more even intensity across the entire image. This technique works because the grayscale conversion focuses on the intensity channel, the blurring relaxes the edges caused by lighting to effect large areas and the subtraction removes the global lighting changes to leave just the localized intensity changes which are typically associated with edges. This is in effect a form of an edge detector but one that better preserves the image colors than most edge detection techniques.

Now let's try detecting colors ....