dmstraker Posted November 13, 2017 Share Posted November 13, 2017 Still trying to figure out Contrast Negate. Would love for some kind and clever person to tell me what the algorithm is. Latest nugget: Duplicate layer. Add Curves to bottom layer. Pull left node all the way up and the right node all the way down. You now have the original image. Indeed, if you take an image and just do the curves inversion on it, the result looks like a Contrast Negate. So is it something to do with inverting the luminance? Quote Dave Straker Cameras: Sony A7R2, RX100V Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11" Favourite word: Aha. For me and for others. Link to comment Share on other sites More sharing options...
Staff Callum Posted November 16, 2017 Staff Share Posted November 16, 2017 Hi Dmstraker, I have spoken to James (the lovely voice behind our tutorials) and he has informed me that Contrast Negate is used for text. As it will make the colour of the text contrast the colour of the object behind it to ensure the text is legible you can find an example below Thanks Callum dmstraker 1 Quote Please tag me using @ in your reply so I can be sure to respond ASAP. Link to comment Share on other sites More sharing options...
dmstraker Posted November 16, 2017 Author Share Posted November 16, 2017 Thanks, Callum (and James). Very helpful. Still curious about the algorithm it uses... Quote Dave Straker Cameras: Sony A7R2, RX100V Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11" Favourite word: Aha. For me and for others. Link to comment Share on other sites More sharing options...
jenkm Posted December 20, 2017 Share Posted December 20, 2017 If blend color Luminosity > 50% then: All pixels with Luminosity values less 50% are replaced by the blend color, and the pixels with Luminosity greater 50% are replaced by inverted blend color. If blend color Luminosity < 50% then opposite: All pixels with Luminosity values less 50% are replaced by the inverted blend color, and the pixels with Luminosity greater 50% are replaced by blend color. So this Contrast Negate mode is some kind of two-tone Posterization. dmstraker 1 Quote Link to comment Share on other sites More sharing options...
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