rbfigueira Posted August 5, 2015 Share Posted August 5, 2015 Hi guys, I do this in Photoshop to normalize the R, G, and B curves for the negative film (yes, I scan 35mm film) : - Create a new 'Curves' layer. - Click the little arrow at the top right of the Curves properties window, and select "Auto Options...". - Click "Enhance Per Channel Contrast" and "Snap Neutral Midtones", and set the shadow and highlight clipping to "0.01". - Click "Save as Defaults" and then "ok" out of the Auto Options window, and now click the "Auto" button. What I've just done is to normalize the R, G, and B curves for the negative film. A little background: essentially, negative film has characteristic curves for R, G, and B light. But these are not coincident with each other. If you were to take a photograph of a neutral grey patch and look at the histogram of the negative, you'd find that the blue channel would have the highest intensity, followed by green, and then red. What you need is, for a neutral grey patch, to ensure that R = G = B (that, indeed, is the RGB *definition* of "grey"). So in this curves layer, you're correcting for this R, G, B curve offset by forcing the histogram for each colour to use the entire histogram range (that is, you are enhancing the per channel contrast...as per the Auto Option box you checked above). I need to do the same using the Affinity Photo that I have just bought it :) Any way to do this ? Thanks Quote Link to comment Share on other sites More sharing options...
rbfigueira Posted August 6, 2015 Author Share Posted August 6, 2015 Zero answers is not good :// Ok, if you want to ensure that R = G = B channels are equal, what you do ? Like I have mentioned the the idea is correcting this R, G, B curve offset by forcing the histogram for each color to use the entire histogram range. Any approach ? Any Gurus here ? Thanks Quote Link to comment Share on other sites More sharing options...
ronnyb Posted August 6, 2015 Share Posted August 6, 2015 As far as I'm aware, for now AP has no Auto Correct Settings like the ones in PS; you have to do it manually using curves and/or levels... Just go into each channel and set the black, white and gamma points manually... If you can somehow figure out a standard shift, you may want to save it as a preset. Hope that helps... Leigh 1 Quote 2021 16” Macbook Pro w/ M1 Max 10c cpu /24c gpu, 32 GB RAM, 1TB SSD, Ventura 13.6 2018 11" iPad Pro w/ A12X cpu/gpu, 256 GB, iPadOS 17 Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.