How can I isolate the black and dark gray areas of multiple photos in Photoshop?
Asked 3/4/2016
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2 answers
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I’m photographing cards/posters that are basically grayscale, and I need to keep only the black portions from each image. Because these are photos, I need some tolerance for dark grays rather than selecting only pure black. Is there a reusable Photoshop method for this, or at least a faster way than running Select > Color Range on every file individually?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
10y ago
2 Answers
2
Right click your mask layer and click Blending Options (also accessible if you double click the blank area to the right of the layer name, though I often accidentally select the layer name when I try to do that).
There's an option there called Blend If: and a range of luminance sliders which I think could be used for your purposes.
You'd still have to set it for each image, rather it being a mask layer you could drag and drop (or put in the new Asset Library - which I still haven't figured out btw). However the sliders have numerical values which could be very quickly replicated on each image; I'd expect this to take a fraction as long as running the finicky Select > Color Range tool over and over.
Originally by user48183. Source · Licensed CC BY-SA 4.0
user48183
10y ago
0
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A practical Photoshop approach is to use the layer’s Blending Options and the Blend If sliders. Open the layer’s blending options, then use the luminance sliders to hide lighter tones and keep only the darker parts of the image. This gives you the tolerance you need for black plus dark gray, which is useful for photographed material rather than pure flat graphics.
It isn’t a drag-and-drop mask you can apply identically to every image, because each photo may need slight adjustment. But once you find slider values that work, you can quickly reuse those numeric settings across similar files, which is usually faster and less fiddly than running Select > Color Range on each image.
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