"liaM" wrote in message
I’m stumped by the following problem : the photo consists of a yellow background to hundreds of green and blue polka dots ; how can I make all of the green polka dots disappear into the yellow background (while keeping the blue polka dots intact) ?
How to do this in one go, and not having to erase the dots one by one ?
PS. I use Photoshop 5
Good puzzle. Use a mask combined with a curved version of your original image as follows:
Duplicate the image, and convert the duplicate to Lab mode. You’ll be using the a channel of this image as a mask.
Duplicate the original image to a new layer, and copy the a channel of the Lab image to the layer mask of the duplicate layer. The quickest way to do this is to use Image>Calculations to copy the b channel as a selection to the original document, then create a layer mask to show the selection. The polka dots, which will be light colored in the a channel – use Levels to bump the contrast of the layer mask, and add red to the duplicated layer until it matches the yellow background. It will take some fiddling to get a good match, and to eliminate fringes from what is left of the green polka dots. You may find Image>Adjust>Hue/Sat to be helpful in getting a good match to the yellow.
I haven’t actually tried the above procedure, so it may contain errors. The principal is to use the a channel as a mask for the green parts of the image – blue and yellow are absent from this layer so there should be good selection for the green dots, with very little crossover between luminance, or the blue and yellow areas.
Perhaps you can post the image and some of us can give it a try. —
Mike Russell – www.curvemeister.com
