Asparria

I think I said that it works too fast. Although an external image can be applied to a layer in AP, it does it in a very restrictive way: Suppose we have a photo in the LAB colorspace, let's call it BASE. Get a greyscale layer of the A channel. Export this layer as a Greyscale/16bit Image, lets call it A-CHANNEL; we can agree that this is a One-Channel-Only image. Suppose now that I wat to substitute the B channel of BASE with the A-CHANNEL image we just created. To do this, we select in AP the B channel only (eye + pen) in the channels tab; then, apply-image (normal mode), load image A-CHANNEL. No luck, the result of the operation is a solid 50% grey in the B-channel. I expected the A-CHANNEL greyscale image, that has only one layer, to substitute the B channel of BASE. It seems that AP is creating dummy A and B channels in the A-CHANNEL image, with solid 50% grey, and then applying the dummy B channel to the B channel of BASE. As in AP is not possible to select the channel to be applied as source, it is not possible to do channel blending. I think that even a simple channel swap cannot be done. Any help will be greatly appreciated.

Thank you very very much Andy, It works!. Unfortunately, as Coranda said, requiring a layer to be saved out and reload is a severe workflow limitation. It would be perfect to be able to to select as source a channel or a layer (in addition to load an image from outside). Would this be doable? Thanks again :)

Hi JamesRitson, Thanks for your suggestion. It works as you said, however, it seems that in this way we are only substituting one layer by another. The functionality we are referring to implies the blending of two channels using any blending mode (i.e. Normal, Darken, Lighten, Multiply, etc.) and any opacity. Another way would be to create an ad-hoc grayscale layer and blending that layer into a single channel. Thanks again. Any other suggestion is welcomed.

Thank you very much Coranda for your help. Regarding your comments: 1. You are right. If I might add, to clarify: blending (e.g. normal, darken, lighten, multiply, etc.) with a custom opacity is the usual approach. As you said, most of the time the target is a single channel. 2. If I understand you correctly, the target layer is the only one being modified, the source should be left untouched. Both, source and target, could be either a grayscale layer or a channel. 3. As far as I know this is the case, yes. To be consistent, the blending algorithm should behave exactly the same, either as layers or inside the "apply image" window. When creating a layer from a channel, the pixel values should match exactly. Please note that this is not the same as PS "Image: Mode > Grayscale", were PS makes an average of the three RGB channels in proportion 3R-6G-1B (source: "Professional Photoshop" by Dan Margulis). AP might be using another formula, though. 4. I cannot check it right now I don't have a PS available. Nevertheless, please note that creating grayscale images from RGBs in PS is performed by averaging the three RGB channels (check point 3. above). If I am not mistaken (please correct me if I am wrong), what we want is exact value match, i.e. a 100R in the red channel, when converted into a grayscale layer, should be equal to 42L in LAB (or a 100R-100G-100B gray).

I hope more people join this request. Apply Image is necessary in any serious photo workflow.

I've been the last week trying to find a workaround with no luck. If right now we cannot blend any two channels, or a layer with a channel, maybe it is possible to substitute a channel with a grayscale image. It seems that we can get grayscale layers from the channels, and we can blend them as we wish and produce a new grayscale layer exactly as we want. Unfortunately, I was not able to substitute a channel with this layer, it's like channels are "read-only". If we could edit a channel and substitute it with an ad-hoc grayscale layer, we might have a good workaround until the Apply Image functionality is implemented. Any idea or suggestion?

I second this request. We need to be able to blend channels, blend a layer with a channel, and substitute a channel by an ad-hoc greyscale image; either in RGB, CMYK or LAB (please note that even for RGB outputs, CMYK and LAB can be really important). Unfortunately, I don't see this feature in the "Affinity Photo feature roadmap". The functionality of Apply Image is a must in color correction and in any serious photo workflow. I hope the Serif Team can take this request into consideration. I'm crossing my fingers.