UdoBerlin Posted October 12, 2022 Share Posted October 12, 2022 I would like to keep only the cyan channel in a CMYK image and export to PDF. Quote Link to comment Share on other sites More sharing options...
Staff Lee_T Posted October 12, 2022 Staff Share Posted October 12, 2022 Hi UdoBerlin, You can use the curves adjustment to reduce the YMK to 0. (dragging the right node to the bottom on each channel aside from alpha) Lee UdoBerlin and Old Bruce 2 Quote Link to comment Share on other sites More sharing options...
Staff Dan C Posted October 12, 2022 Staff Share Posted October 12, 2022 Hi @UdoBerlin, Another option is the following: If your document has multiple layers, right click the top layer and select 'Merge Visible', to create one new Pixel layer with a full representation of the document. Select this Layer in the Layers Studio and navigate to the Channels Studio Right click on Pixel Magenta & Pixel Yellow, selecting Clear in the menu that appears. Note you will now need to decide if you wish to include the Black channel or not If you wish to include this, you can export the image as-is, if not, please right click and select Fill for the Black channel Please see my screen recording below showing this - 2022-10-12 16-10-19.mp4 I hope this helps Old Bruce, UdoBerlin and Lee_T 2 1 Quote Link to comment Share on other sites More sharing options...
UdoBerlin Posted October 12, 2022 Author Share Posted October 12, 2022 Thanks to both of you! Dan’s answer was exactly what I wanted. Quote Link to comment Share on other sites More sharing options...
walt.farrell Posted October 12, 2022 Share Posted October 12, 2022 2 hours ago, Dan C said: Note you will now need to decide if you wish to include the Black channel or not If you wish to include this, you can export the image as-is, if not, please right click and select Fill for the Black channel I'm curious about that, Dan. I had never tried clearing channels before, so I tried your instructions. I was surprised to note that if I Clear (rather than Filling) the Black channel at the final step, I lose the entire image. Why does that happen? Quote -- Walt Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases PC: Desktop: Windows 11 Pro, version 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 Laptop: Windows 11 Pro, version 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU. iPad: iPad Pro M1, 12.9": iPadOS 17.4.1, Apple Pencil 2, Magic Keyboard Mac: 2023 M2 MacBook Air 15", 16GB memory, macOS Sonoma 14.4.1 Link to comment Share on other sites More sharing options...
R C-R Posted October 12, 2022 Share Posted October 12, 2022 7 hours ago, Dan C said: Another option is the following: Just wanted to mention that a macro could be made to do this in one step. It could be one of several in a custom macro library category, of six related macros, one each for C, Y, M reductions with & without retaining the black layer. That said, I am also surprised that clearing the black channel rather than filling it turns the layer black. Quote All 3 1.10.8, & all 3 V2.4.2 Mac apps; 2020 iMac 27"; 3.8GHz i7, Radeon Pro 5700, 32GB RAM; macOS 10.15.7 Affinity Photo 1.10.8; Affinity Designer 1.108; & all 3 V2 apps for iPad; 6th Generation iPad 32 GB; Apple Pencil; iPadOS 15.7 Link to comment Share on other sites More sharing options...
thomaso Posted October 13, 2022 Share Posted October 13, 2022 17 hours ago, walt.farrell said: I was surprised to note that if I Clear (rather than Filling) the Black channel at the final step, I lose the entire image. Why does that happen? You don't lose the entire image, it's just that black gets most dominant as it represents luminosity/brightness in CMY + K (…displayed with an RGB hardware). If you then invert Black, the image "comes back" but pale (= empty composite black channel). I am rather confused that Filling and Clearing CMY appear both the same AND work opposite to Black. Or: CMY get filled with White while K gets filled with Black. If I use "Clear" (or "Fill") for CYAN it needs to get inverted before I see the expected CYAN domination whereas Clearing Black shows directly the black. Is here the difference of additive / subtractive working that needs to get "repaired"? walt.farrell 1 Quote macOS 10.14.6 | MacBookPro Retina 15" | Eizo 27" | Affinity V1 Link to comment Share on other sites More sharing options...
Staff Dan C Posted October 13, 2022 Staff Share Posted October 13, 2022 18 hours ago, walt.farrell said: I was surprised to note that if I Clear (rather than Filling) the Black channel at the final step, I lose the entire image. Why does that happen? 13 hours ago, R C-R said: That said, I am also surprised that clearing the black channel rather than filling it turns the layer black. 11 hours ago, thomaso said: I am rather confused that Filling and Clearing CMY appear both the same AND work opposite to Black. Or: CMY get filled with White while K gets filled with Black. If I use "Clear" (or "Fill") for CYAN it needs to get inverted before I see the expected CYAN domination whereas Clearing Black shows directly the black. Is here the difference of additive / subtractive working that needs to get "repaired"? I've been discussing this internally and we believe it may be an oversight from RGB/A documents, where the 4th channel is calculated as the 'Alpha' - therefore using 'Clear' on the Alpha would fill the channel in black (removing all Alpha) and using 'Fill' on the Alpha would set the channel to be empty (filled with 'Alpha'). When in a CMYK document, the K channel seems to be incorrectly using the same understanding as above - but I believe it should be the same behaviour as the CMY channels, so I'm logging this as a bug with our devs now R C-R, walt.farrell and Old Bruce 3 Quote Link to comment Share on other sites More sharing options...
thomaso Posted October 13, 2022 Share Posted October 13, 2022 28 minutes ago, Dan C said: but I believe it should be the same behaviour as the CMY channels Yes, but shouldn't for all 4 channels "Clear" cause an empty channel (white) and "Fill" cause full color (c, y, m, k)? Currently it's different for CMY: both, Clear + Fill, result in a cleared, empty channel while it requires additionally "invert" to get it filled. Quote macOS 10.14.6 | MacBookPro Retina 15" | Eizo 27" | Affinity V1 Link to comment Share on other sites More sharing options...
Staff Dan C Posted October 13, 2022 Staff Share Posted October 13, 2022 17 minutes ago, thomaso said: Currently it's different for CMY: both, Clear + Fill, result in a cleared, empty channel while it requires additionally "invert" to get it filled. Sorry, I had misunderstood that part of your post and was focusing on the K channel - I can see the issue here, I would expect 'Fill' on a C channel to fill with Cyan, as this happens when using 'Fill' on the R channel in an RGB document, so I'm logging this with our devs also R C-R, thomaso and walt.farrell 2 1 Quote Link to comment Share on other sites More sharing options...
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