Copy and Paste into channels

[jonathanm0]

Hi everyone,

I am working with large images, 8k, 16k, etc, and need to process them into various channels. With this file in particular, the Green and Blue channels are empty. I need to copy my Red channel into them. I was searching the forums and discovered from an older post that you have to make a spare channel. I have tried to paste into it, without success. Is there something else I need to be doing here? The source provider of these images uses Photoshop and they literally copy and paste into the channels, which I am unable to do.

Kind regards.

[smadell]

So we meet again @jonathanm0… As you've undoubtedly figured out, Photoshop and Affinity Photo treat channels quite differently, at least insofar as manipulating/editing them. In order to do what you want, take the following steps:  (1) If you are using the Red channel from a single layer, right click on entry in the Channels panel that contains the name of the layer followed by Red. In other words, if your photo is called "Background" then right click on the "Background Red" entry in the Channels panel. It should be the 4th line from the top. (2) If you have more than one layer – perhaps a Background layer and an adjustment or two – right click on the "Composite Red" entry at the top of the Channels panel. (3) Having right clicked on one of those choices, choose "Create Spare Channel" from the drop-down menu. (4) Make sure that the correct layer is selected in the Layers panel. This will be the one with the Red channel filled but with the empty Green and Blue channels. (5) Right click on the "Spare Channel" you just created at the bottom of the Channels panel. (6) Assuming that the layer you're aiming at is called "Background" choose "Load to Background Green" from the drop down menu. (7) Then, right click that same Spare Channel entry and choose "Load to Background Blue" from the drop down.

You should now have duplicated the Red channel into the Blue and Green channels. The layer should now be a monochrome image (since all 3 channels are the same). You can go ahead and delete the Spare Channel, as it has served its purpose.

[jonathanm0]

On 8/12/2022 at 5:59 PM, smadell said:

So we meet again @jonathanm0… As you've undoubtedly figured out, Photoshop and Affinity Photo treat channels quite differently, at least insofar as manipulating/editing them. In order to do what you want, take the following steps:  (1) If you are using the Red channel from a single layer, right click on entry in the Channels panel that contains the name of the layer followed by Red. In other words, if your photo is called "Background" then right click on the "Background Red" entry in the Channels panel. It should be the 4th line from the top. (2) If you have more than one layer – perhaps a Background layer and an adjustment or two – right click on the "Composite Red" entry at the top of the Channels panel. (3) Having right clicked on one of those choices, choose "Create Spare Channel" from the drop-down menu. (4) Make sure that the correct layer is selected in the Layers panel. This will be the one with the Red channel filled but with the empty Green and Blue channels. (5) Right click on the "Spare Channel" you just created at the bottom of the Channels panel. (6) Assuming that the layer you're aiming at is called "Background" choose "Load to Background Green" from the drop down menu. (7) Then, right click that same Spare Channel entry and choose "Load to Background Blue" from the drop down.

You should now have duplicated the Red channel into the Blue and Green channels. The layer should now be a monochrome image (since all 3 channels are the same). You can go ahead and delete the Spare Channel, as it has served its purpose.

Hi @smadell! Sorry for the delay in getting back to you. Thank you so much for the detailed response. I have saved this into my notes for reference. It worked perfectly.

Is it possible to delete the Alpha Channel?

Kind regards.

[smadell]

I'm glad this helped you out. As for deleting the Alpha Channel, I'm not sure if you can actually get rid of it (although, if you save as a JPG the file "probably" doesn't have an alpha channel). But you can (i) fill it with black, or (ii) clear it out entirely. For either of those choices, right click on the Background Alpha channel (in the Channels panel) and choose "Fill" for the first option, or "Clear" for the second option.