Alpha Edits

[Lucrecio Poinson]

Iwant the RGB to be pure white (255, 255, 255) and the alpha layer to have a brush effect applied to it. I know how to use the brush, but no matter what combination of masks or layer visibility / channel visibility settings I try, it will never edit ONLY the alpha channel, leaving the rest undisturbed.

Under the Layers tab, right click the layer to edit and choose Add Layer Mask. A dialog box will ask you how you want the layer mask to be initialized. Presuming you'll start with a visible image and brush away the part you want transparent, the best choice is White (Full Opacity). Click Add.

Under the Layers tab, you should now see the white thumbnail of the layer mask, next to the thumbmail of the layer image. Click on the thumbnail to edit the layer mask. Choose your brush effect and the color black, and apply your brush effect.

If you prefer to start with a transparent image and brush on the part you want visible, just start with a layer mask which is Black (Full Transparency) and apply your brush effect to the layer mask with the color white.

Just a simple solution only if you want to change the transparency of the layer.Choose eraser tool. There is an option to change the opacity of the eraser under tool options. Just adjust it to your requirement(say 75). Now apply the eraser.

We have been asking for years to edit textures for videogames to be able to save the alpha in a tga, png or tiff... without destroying the rest of the RGB channels info and we still have no answer to the only thing that prevents us from using Affinity for videogames.

Simply that alpha does not destroy the color information in those formats. We can't work with Affinity, we can't export our work to a game engine. I don't understand how we don't have that but then you put us a normals map filter...

It's one of the reasons I can't commit to Affinity Photo for all my work. It feels silly to do 90% of my work happily in Affinity and the open a web app like photopea.com so I can do some basic alpha channel editing.

Preparing the TGA file for editing

Move the alpha channel to the new mask layer.

1. Open the file for editing and make sure the document background is transparent.

2. Select the background layer in the Layers panel.

3. Create a mask from Background Alpha in the "Channels" pane.

Removal of the original alpha and discovery of RGB pixels:

4. Select the Background layer again;

5. Select the fill option for "Background Alpha" in the "Channels" pane.

6. Now you can hide the mask layer and check if information in RGB channels is preserved.

ATTENTION!!!!!!!

Keep the mask position on the top layer and under no circumstances merge it with other layers or flatten the file before exporting. In Affinity Photo, it seems that masks remove information about other channels from the layer they are pinned to, so be sure to keep the mask on a separate layer.

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

For whatever it is worth, the alpha editing issue is the one thing that is stopping me from openly and freely suggesting Affinity Photo to other gamedev people. And I don't think linking them to a tutorial when they ask if you can edit alpha maps is doing affinity any favours (it makes the software seem a lot more complicated than the competition, and that's not really true).

I prefer to stay away from the Alpha channel. The Alpha channel behaves very strangely and is the only channel that needs the eraser to edit. While the brush only affects the selected channel, the eraser does not. When the eraser reaches full black, it starts affecting all other color channels and removes information from them.

I definitely prefer masks on separate layers. Their editing is much more intuitive and I don't need an eraser. I hold [alt] and click on the mask layer to enter mask edit mode. In the mask mode, I have a preview and can edit it like normal channels. Interestingly, all RGB channels are affected simultaneously, but not channel A. In the mask, this channel is not editable.

I understand your point of view and I'm not surprised at all. I have a similar dilemma myself.

For texture editing, I prefer to recommend software created for this purpose. AP can only supplement such a program, but it will never reach the same level because it is not designed to do so. An example here is Quixel Mixer. But gamedev is not only about textures

I just bought the V2 version and it seems to only work for TGAs. So if another artist used tiff you are screwed. I want to switch to affinity photo but just because of the alpha channel it is basically unusable.

Affinity stated consistently it does work as designed. This thread is a feature request, and it will become more likely to getting implemented if more users add their vote and provide arguments how this would improve their workflows and why workarounds are not sufficient.

Hello there !

I'd like to point up how RGBA channels are handled. I'm a game artist who is used to heavily work with channels and being able to copy/paste to swap them, get data, transfer from one texture to another is crucial. And I work my 2D source files either in .PSD or .TGA, so import/Export should be seamless and without any compression.

Please improve how channels are imported when an alpha channel is there (currently it destroys data and using a complex workaround is not a great solution. At least it shows how much we need it)

Please also reach at least what photoshop do with channels pannel (copy/paste, display, ux design). I'm not against a better-than-photoshop pannel of course, but until then, a simple copy would greatly help

Looking to make textures for Unity3d, and I'm stuck at what seems to be a simple stage. My goal is to create an RGBA image, with color information for every pixel, and a separate alpha channel. These two components get fed into Unity as base color and reflection strength, respectively. (Using "Reflective/Bumped Diffuse" material.)

If I use masking tools in Photoshop, I can erase parts of the output image (transparency). However, I would like to keep the original RBG color information when output, and not just have "blank" areas. Also, it would be nice if I could do it non-destructively, ie. the final alpha channel is dependent on a standard layer, or built from a path object, etc.

Note: When saving you need to be careful about file formats. Things like .Tiff & .TGA save the full alpha channel independent of color information. However Photoshop doesn't allow this with PNG, much to many developers annoyance. It will not properly save Alpha Channel images and tends to strip out color information for fully transparent areas to compress file size.

The layer will then have two "images" associated with it - the RGBA image and a grayscale layer mask which acts as an extra (multiplicative) alpha channel. You can click either of these images to select which one will be edited.

In the GIMP, one way would be to split the image into layers for each channel. Select "Colors->Components->Decompose" and choose RGBA or whatever channels you want to break into layers. Then edit your individual alpha and color channels as you see fit (they should be greyscale), then go "Colors->Components->Compose" choose your desired channel layout and choose your layers to use for each channel.

Also, you can use the "Channels" dialogue. It should be a part of the default toolbox things, but if not you can select "Windows->Dockable Dialogues->Channels". You can toggle visibility of each color channel, and by clicking and highlighting the channel names you can choose which ones to edit individually (it looks like it preserves color with alpha, although I don't see a way to "hide" the alpha while editing without hiding the entire image...).

One alternative is to write your own content processor to perform the operation you want. That way you could simply give your "reflectivity" layer (or even multiple reflectivity layers) a special name, and have the content processor put that data in the alpha channel for you. (Or indeed implement any kind of process that you like.)

If you were using XNA and The GIMP (this is what I use and am familiar with), then it would be very easy for you to add this XCF importer to your content pipeline and make the necessary modifications to process specially named layers.

New to AP, trying to figure out how to edit the alpha channel of a TIFF file. In the Channels panel, I click Composite Alpha to make the alpha channel editable, but some tools seem to work inconsistently or not at all in the alpha channel. For example, I can select all and Fill the alpha channel with white, but not with black or gray. Same with the Paint Brush tool. And it won't let me paste into the channel, pasting with the alpha channel editable and the other channels set to non-editable, the pasted image does not go into the alpha channel. If I do fill the alpha channel with black (I don't remember how I did it once), the image disappears and and I can no longer see it. Is there a way to edit the alpha channel as with a normal layer - using fill, brush, paste, etc.? Is there a way to edit the alpha channel and still see the entire image? Better yet, is there a setting to always see the entire image, regardless of the alpha channel (Transparent Background doesn't do it)?

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