michaelsboost Posted August 9, 2018 Share Posted August 9, 2018 In GIMP if I wanted to remove the white background on the attached image there's an easy way to do it by going to Colors/Color to Alpha. I know if the background is white I can go to Filters/Colors/Erase White Paper but that only works if the color is white which is fine for my image but what about if it is Cyan? My question is how can I do this Color to Alpha thing in Affinity Photo? Quote "Procrastination is the enemy of productivity!" ~Michael Link to comment Share on other sites More sharing options...
carl123 Posted August 9, 2018 Share Posted August 9, 2018 One way... If you have black line art on a Cyan/coloured background Add a Black and White Adjustment layer to it Bake in the adjustment (Rasterise, Merge, Flatten etc) Then use the Filters > Colours > Erase White Paper command firstdefence, Alfred and michaelsboost 2 1 Quote To save time I am currently using an automated AI to reply to some posts on this forum. If any of "my" posts are wrong or appear to be total b*ll*cks they are the ones generated by the AI. If correct they were probably mine. I apologise for any mistakes made by my AI - I'm sure it will improve with time. Link to comment Share on other sites More sharing options...
firstdefence Posted August 9, 2018 Share Posted August 9, 2018 Using Colours to Alpha in Gimp is Okay for solid even colours, but with gradients and coloured shading its next to useless. It would be faster to trace the black lines and scan it in and convert to vectors. Quote iMac 27" 2019 Somona 14.3.1, iMac 27" Affinity Designer, Photo & Publisher V1 & V2, Adobe, Inkscape, Vectorstyler, Blender, C4D, Sketchup + more... XP-Pen Artist-22E, - iPad Pro 12.9 (Please refrain from licking the screen while using this forum) Affinity Help - Affinity Desktop Tutorials - Feedback - FAQ - most asked questions Link to comment Share on other sites More sharing options...
Pšenda Posted August 9, 2018 Share Posted August 9, 2018 You can try this. Quote Affinity Store (MSI/EXE): Affinity Suite (ADe, APh, APu) 2.4.0.2301 Dell OptiPlex 7060, i5-8500 3.00 GHz, 16 GB, Intel UHD Graphics 630, Dell P2417H 1920 x 1080, Windows 11 Pro, Version 23H2, Build 22631.3155. Dell Latitude E5570, i5-6440HQ 2.60 GHz, 8 GB, Intel HD Graphics 530, 1920 x 1080, Windows 11 Pro, Version 23H2, Build 22631.3155. Intel NUC5PGYH, Pentium N3700 2.40 GHz, 8 GB, Intel HD Graphics, EIZO EV2456 1920 x 1200, Windows 10 Pro, Version 21H1, Build 19043.2130. Link to comment Share on other sites More sharing options...
firstdefence Posted August 9, 2018 Share Posted August 9, 2018 It might be an idea to explain the reason for the question. Are you asking if the Black lines are Cyan or the image itself is coloured in-between the black lines is cyan? This is the Deviantart 18th Birthday Asset image that you can download and colour. Quote iMac 27" 2019 Somona 14.3.1, iMac 27" Affinity Designer, Photo & Publisher V1 & V2, Adobe, Inkscape, Vectorstyler, Blender, C4D, Sketchup + more... XP-Pen Artist-22E, - iPad Pro 12.9 (Please refrain from licking the screen while using this forum) Affinity Help - Affinity Desktop Tutorials - Feedback - FAQ - most asked questions Link to comment Share on other sites More sharing options...
Alfred Posted August 9, 2018 Share Posted August 9, 2018 34 minutes ago, firstdefence said: Are you asking if the Black lines are Cyan or the image itself is coloured in-between the black lines is cyan? I read it as the latter: Quote I know if the background is white I can go to Filters/Colors/Erase White Paper but that only works if the color is white which is fine for my image but what about if [the background color] is Cyan? In other words, I think the OP wants to remove the cyan background from an image like this: firstdefence and michaelsboost 2 Quote Alfred Affinity Designer/Photo/Publisher 2 for Windows • Windows 10 Home/Pro Affinity Designer/Photo/Publisher 2 for iPad • iPadOS 17.4.1 (iPad 7th gen) Link to comment Share on other sites More sharing options...
firstdefence Posted August 9, 2018 Share Posted August 9, 2018 15 minutes ago, αℓƒяє∂ said: I read it as the latter: Then Carl123's method would be perfect. Alfred 1 Quote iMac 27" 2019 Somona 14.3.1, iMac 27" Affinity Designer, Photo & Publisher V1 & V2, Adobe, Inkscape, Vectorstyler, Blender, C4D, Sketchup + more... XP-Pen Artist-22E, - iPad Pro 12.9 (Please refrain from licking the screen while using this forum) Affinity Help - Affinity Desktop Tutorials - Feedback - FAQ - most asked questions Link to comment Share on other sites More sharing options...
smadell Posted August 9, 2018 Share Posted August 9, 2018 With the pixel layer selected... 1) Select Sampled Color... so that the background color is selected. Click the Apply button. 2) Invert Selection. Everything BUT the background color is selected. 3) In the Channels panel, right click the Pixel selection and choose Create Spare Channel. 4) Right click on the thumbnail of the newly created Spare Channel. Choose Load to Pixel Alpha. This should make the background color transparent. Przemysław, michaelsboost and Alfred 2 1 Quote Affinity Photo 2, Affinity Publisher 2, Affinity Designer 2 (latest retail versions) - desktop & iPad Culling - FastRawViewer; Raw Developer - Capture One Pro; Asset Management - Photo Supreme Mac Studio with M2 Max (2023}; 64 GB RAM; macOS 13 (Ventura); Mac Studio Display - iPad Air 4th Gen; iPadOS 17 Link to comment Share on other sites More sharing options...
lepr Posted August 9, 2018 Share Posted August 9, 2018 . Alfred 1 Quote Link to comment Share on other sites More sharing options...
smadell Posted August 9, 2018 Share Posted August 9, 2018 owenr... I’m sure that your solution would work. Actually another straightforward way to get the VISUAL results would be to use a mask. BUT, the OP wanted to move the background into the Alpha channel. Hence, my answer. Quote Affinity Photo 2, Affinity Publisher 2, Affinity Designer 2 (latest retail versions) - desktop & iPad Culling - FastRawViewer; Raw Developer - Capture One Pro; Asset Management - Photo Supreme Mac Studio with M2 Max (2023}; 64 GB RAM; macOS 13 (Ventura); Mac Studio Display - iPad Air 4th Gen; iPadOS 17 Link to comment Share on other sites More sharing options...
lepr Posted August 9, 2018 Share Posted August 9, 2018 . Quote Link to comment Share on other sites More sharing options...
Alfred Posted August 9, 2018 Share Posted August 9, 2018 3 hours ago, smadell said: the OP wanted to move the background into the Alpha channel On a re-read, I think the OP’s reference to “Colors/Color to Alpha” was just GIMP-speak for “make the selected color transparent”, with no need to move anything explicitly into the Alpha channel. firstdefence 1 Quote Alfred Affinity Designer/Photo/Publisher 2 for Windows • Windows 10 Home/Pro Affinity Designer/Photo/Publisher 2 for iPad • iPadOS 17.4.1 (iPad 7th gen) Link to comment Share on other sites More sharing options...
Move Along People Posted August 9, 2018 Share Posted August 9, 2018 - Quote Move Along people,nothing to see here Link to comment Share on other sites More sharing options...
lepr Posted August 9, 2018 Share Posted August 9, 2018 . Move Along People 1 Quote Link to comment Share on other sites More sharing options...
Medical Officer Bones Posted August 9, 2018 Share Posted August 9, 2018 1 hour ago, owenr said: Anyway, your method (and my simplification of it) does not solve the problem where pixels contain a blend of foreground and background colour. Just now, owenr said: That doesn't solve the problem of fringing in the pixels that contained a blend of foreground and background colour. You are right: Gimp's Color to Alpha function 'unmultiplies' (for a lack of better wording) the selected colour, just like Affinity Photo's "Erase White Paper" function. Other applications have similar functions: Krita's "Color to Alpha", PhotoLine's "Color to Transparency", and the old PS "Unmultiply" plugin from Ayato come to mind. Photoshop never had a native option built-in, oddly enough. Another classic PS plugin was "Peel Off White", but just like Ayato's Unmultiply plugin both developers decided it was too much of a bother to keep up with Adobe's ever changing plugin architecture, and decided to call it a day. Ayato re-created his filter in FilterForge, while the POW plugin creator decided to create a separate paid-for utility called "Peeler". Reference and interesting discussion regarding this technique and alternatives: https://forums.adobe.com/thread/2067336 Anyway, it's nice that Affinity Photo offers a similar option, although a bit of a shame that it will only work with white (and black when the image is inverted first) backgrounds. I either use Krita or PhotoLine for this job. Krita is pretty good and free, while PhotoLine's Color to Transparency filter has the most options and is entirely non-destructive (can be stacked if necessary). Gimp's version doesn't always yield good results" more control is needed. Krita is a good free option, and does a very good job and includes a threshold slider. I hope the Photo devs will introduce more control options at some point. It's handy to have "Erase White Paper", but sort-of limited. Although I understand that most users probably just need to erase the white from existing clip art, it would be nice if a colour picker and threshold slider is added. While we wait and hope for this, if you do need to unmultiply any coloured background from an image, just open it in Krita and use its Color to Alpha option. michaelsboost 1 Quote Link to comment Share on other sites More sharing options...
michaelsboost Posted August 9, 2018 Author Share Posted August 9, 2018 Thank's everyone huge help. I'm still getting used to Affinity's way of doing things. Quote "Procrastination is the enemy of productivity!" ~Michael Link to comment Share on other sites More sharing options...
Move Along People Posted August 9, 2018 Share Posted August 9, 2018 - michaelsboost 1 Quote Move Along people,nothing to see here Link to comment Share on other sites More sharing options...
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