dmorigin Posted December 7, 2018 Share Posted December 7, 2018 I have a problem packing maps in the four channels. I know the tutorial video for Channel Packing. However, the alpha channel is not used in this tutorial. But I use exactly the technique shown there. As soon as you use the alpha channel, the RGB channels are modified according to the information in the alpha channel. This is probably due to how Affinity Photo uses the alpha channel. This is not only used to give the transparency, but also to create a gradient. I have added 3 images to show this better. The image "all_channels.jpg" shows the resulting image as you would normally save it as png or jpg. The image "only_alpha_channel.jpg" shows how Affinity Photo created the alpha channel. You can see the soft edges. The image "only_red_channel.jpg" shows the content of the red channel. Some edges are soft others are not. Where the colors red and green overlap a gradient is created from 1 to 0 (or 255 - 0 in 8Bit). However, where no color is adjacent, this gradient is created by the alpha channel and the color value remains at 1 (255 in 8Bit). The problem now is that as soon as you put data into the alpha channel the RGB channels will be recalculated. This happens if you first fill the alpha channel and then the RGB channels or first the RGB channels and then the alpha channel. If you now have a normal map and want to place the displacement map in the alpha channel, the normal map will be destroyed by the recalculation of the RGB channels based on the information in the alpha channel. Is there a way to prevent this recalculation? Quote Link to comment Share on other sites More sharing options...
Staff stokerg Posted December 8, 2018 Staff Share Posted December 8, 2018 Hi dmorigin, My channel packing knowledge is very limited but i believe this has come up before here. Sadly the user didn't return with the final answer from our member of staff James who would know the answer to this. I'll drop James an email and will post the reply here. Quote Link to comment Share on other sites More sharing options...
lepr Posted December 8, 2018 Share Posted December 8, 2018 . Alfred and yutoVR 1 1 Quote Link to comment Share on other sites More sharing options...
dmorigin Posted December 8, 2018 Author Share Posted December 8, 2018 It works until you export it as a file (e.g. Tiff). Then everything is the same again. alpha_channel_test.afphoto Quote Link to comment Share on other sites More sharing options...
lepr Posted December 8, 2018 Share Posted December 8, 2018 . Quote Link to comment Share on other sites More sharing options...
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