How to deal with alpha channel?

[buck-w]

I still use Ron Scott's QFX (anyone know that?) for alpha channel work on uncompressed tiffs.  The reason is, QFX has a nice batch queue scripting language and I can load, save and do boolean operations on alpha.  In a few moments I can process hundreds of images blazingly fast.

I've never been able to figure out how to do anything in Photoshop with alpha channel.  Any search on the subject doesn't reveal much.  Say I have an 8 bit tiff and I want to insert that as alpha into a 24 bit tiff, then save it as a 32 bit tiff.  How the heck is that accomplished?

Thanks in advance.

[D Fosse]

The trick is to target the alpha channel in the Channels panel. To do that, just click it in the panel. Then you can do anything to it, just like any other image.  Copy the first image and paste it into the destination alpha, that's all it takes.

Whether you want the other RGB channels visible or not during this, is optional. Turn on or off with the eye icon. If RGB is visible, the alpha channel appears as a red overlay. Otherwise, it's black and white.

[buck-w]

Thanks for the info. I look forward to getting a handle on this.

[buck-w]

"Copy the first image and paste it into the destination alpha, that's all it takes."

???  First image.

I want to save an existing Alpha channel out to a file (8 bit) and open another greyscale image and make that image the Alpha channel of the previous image, how does that work?  Not that I'm always doing this, but both of those operations complete my current state of ignorance on the subject.  Thank-o mighty.

[D Fosse · Accepted solution]

Copy the source image. Select all > Copy.

Then go to the file where you want to use it as alpha channel. Target the alpha if you already have one. Paste. Done.

If you don't have an existing alpha channel, add one as Brad describes. Target it. Paste. Done.

[buck-w]

It worked.  Thanks.

[Brad @ Roaring Mouse]

Further to @D Fosse's answer, open up your Channels palette for the image, and if there isn't currently an alpha channel, click on the dropdown pancake icon to Add one (New Channel)

[Semaphoric · Accepted solution]

Once you have the Alpha channels, be sure to check out Image > Calculations.

[buck-w]

Sound like you might be suggesting I can do some of those boolean operations.

[buck-w]

Well, I was able to use Calcs to boolean my alpha.  I duped my alpha channel.  Altered the duped alpha.  Used Calc to subtract one from the other to a new channel.  Deleted the two previous alpha channels.  Saved it to a new image and it contained the booleaned alpha.  Awesome!  Thanks for that tip.

High off that, I opened the original masked tiff and tried to save the alpha channel out to a file.  Haven't figured that one out.  Help and posts talk about selecting alpha channel, having layers visible in the layer panel that are included in the selected channel.  Doing Ctrl-A and then Edit, Copy Merged, but it is greyed out.  I also turned on legacy export and tried another posts process.  Couldn't make that happen either.

So if I want to save an existing Alpha channel out to a file (8 bit) and open another greyscale image and make that image the Alpha channel of the previous image, how does that work?

[buck-w]

Forget about my additional question.  It was answered above and I tried it and it worked.

Thanks for everyone's assistance with my lack of knowledge with this program.

[Stephen Marsh]

@buck-w 
It would be helpful if you can provide before and after images or explain in simple steps.

[buck-w]

I'm not sure what you are talking about.  I don't know how to do it in PS yet, so I have nothing to show.  The example I wrote about in the original post is about as simple as it gets.  If you are talking about the boolean stuff, in QFX, I can take an image with alpha, then replace the alpha, or intersect it with another alpha, do a union between the two or, what I most do, subtract one alpha from the other.  The image shows QFX's Alpha menu and queue where I can loop process a numbered sequence with a few lines of script.  (Yep, that program has been out of print for a good while.)

I do this stuff on image sequences rendered out of 3ds Max animation software, so I'm not talking about general photo work, but specialized manipulation of 3D image sequences.

[Stephen Marsh]

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@buck-w wrote:

I'm not sure what you are talking about. 

🙂 That goes for both of us then!

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I don't know how to do it in PS yet, so I have nothing to show. The example I wrote about in the original post is about as simple as it gets.

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The screenshot that you have provided is a good start. I meant a before-after screenshot result of the actual image input (x2 files) and output (x1) file... Or even better, the original images and the combined image so that those interested in helping you can see what is going on firsthand. Writing about something visual can be hard – a picture is worth a thousand words!

A download link to a file-sharing site would be best, such as your Adobe CC shares, DropBox, OneDrive, GoogleDrive or one of many other services.

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If you are talking about the boolean stuff, in QFX, I can take an image with alpha, then replace the alpha, or intersect it with another alpha, do a union between the two or, what I most do, subtract one alpha from the other.  The image shows QFX's Alpha menu and queue where I can loop process a numbered sequence with a few lines of script.  (Yep, that program has been out of print for a good while.)

I do this stuff on image sequences rendered out of 3ds Max animation software, so I'm not talking about general photo work, but specialized manipulation of 3D image sequences.

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3D is not my area, but that shouldn't matter if you can provide samples that can be reproduced in Photoshop.