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I am trying to remove all white pixels from a monochrome (black and black) picture imported into Adobe Photoshop 5.0 LE. The magic wand does not work because it removes contiguous pixels only. Is there any way to remove all white pixels?
Here’s one way to select all the white pixels in Photoshop 5 LE. First copy the image to the clipboard, then go into QuickMask mode, and paste the image to the mask.
Use levels to set everything below 255 to zero, and everything above it to 255. Because of the way Levels is implemented, you will need to do two repetitions of this in order to get absolutely every white pixel. Switch from QuickMask back to normal mode, and pure white pixels will be selected. You may use your favorite method is to get rid of them.
More than likely there are easier and better ways to do what you are trying to do. Full Photoshop has the dust and scratches filter that will do this quickly and easily. Polaroid supplies an excellent plugin and stand alone utility that does this, and it’s free:
http://www.polaroid.com/service/software/poladsr/poladsr.htm l Both of these filters use what is called an "Impulse Filter", which removes noise from an image by replacing the noise with averaged values from nearby pixels. When using these filters, I find myself using the lasso tool to select dust specks from the shadows, followed by a dose of dust and scratches. This avoids degradation of detail in the lighter areas of the image. If this is what you want to do, Polaroid’s Dust and Scratches could save some work.
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Mike Russell – www.curvemeister.com