The script tries to determine if your image is in color or in black and white, and then generates scanner artifacts in color or grey scale accordingly. Sometimes this fails (some black and white images actually contain a little color and some color images happen to have greyscale pixels at the center). Because of this, I recommend that you bypass this color check by adding the keyword
color or the keyword
bw to the file meta data of your image. This is easily done in Adobe Lightroom CC or Adobe Bridge and those keywords are passed on to exported images.