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I have a color picture and want to make it black and white using Curves Adjusments. Is that feasible?
No problem. Change the Mode to Lab Color. It consists of a Lightness channel that controls the tonal scale and the a and b channels which control color. Change the two color channels (a and b) in Curves as shown: dividing the grid horizontally at the center. Then choose the Lightness Curve and adjust the tonal scale as desired. Last, switch back to your previous Mode. Done.
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to get this you have to adjust each channel curve to make all histograms the same. It's quite long and boring process. But why do you need it? Why don't use Black&White adjustment?
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I know in Photoshop there are various options to make a black and white image but I need it ACV file which would be used in the app.
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Although several ACV (Custom curve presets) are part of the Photoshop package and are designed for use in RGB, you will find that if you switch to Lab Color and follow the adjustment instructions I suggested you can then save the curves to the Preset list.
You might label it: Black and White (LAB)
Once saved, it would appear in the Preset list within the Curves panel and perform as expected. Remember : just as the RGB presets will not work in Lab Mode, this Lab preset will not work as expected in RGB mode.
Bottom line: just switch to Lab Color to use the Lab Color preset, modify the L channel if desired and then switch back to your previous Mode.
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Please elaborate, maybe post screenshots to clarify.
Aside from the already mentioned Black&White Adjustment, Hue/Saturation and Gradient Map Layers (edit: and Channel Mixer, …) also offer options.
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No problem. Change the Mode to Lab Color. It consists of a Lightness channel that controls the tonal scale and the a and b channels which control color. Change the two color channels (a and b) in Curves as shown: dividing the grid horizontally at the center. Then choose the Lightness Curve and adjust the tonal scale as desired. Last, switch back to your previous Mode. Done.
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It may be worth pointing out, though, that RGB to Lab to RGB in 8bit may lead to issues.
As Lab is so much bigger than most any RGB Space the conversions might lead to banding.
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Yes, yes, CP. Thanks.