Demo macro to very, very simple color detection in LAB color space.
The RGB image is converted to LAB color space and then the user draws
some freehand-drawn irregularly shaped region to identify a color.
The Delta E (the color difference in LAB color space) is then calculated
for every pixel in the image between that pixel's color and the average
LAB color of the drawn region. The user can then specify a number that
says how close to that color would they like to be. The software will
then find all pixels within that specified Delta E of the color of the drawn region.