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How to import an alpha channel from .PSD file?

Jun 17, 2009 7:45 AM

I have a photoshop file (.psd) with an alpha channel. When I import this file into AE, I do not see the alpha being available or perhaps I don't know how to find it. I've followed this instruction but nothing happens afterwards. Okay, so my question is, when I drop the .psd file into my comp, how or where do I enble the alpha channel?

 
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  • Currently Being Moderated
    Jun 17, 2009 8:06 AM   in reply to aljCharlie

    If your photoshop layers have traspency, that transparency (alpha information) is automatically preserved when you import your PSD file into After Effects.

    Are you importing your photoshop file as a composition? As footage?

    How many layers are in your PSD file?

    Do you have a fourth channel in the channel box of your photoshop file (alpha)?

     

    If you import your PSD as footage (merged layers) AE should recognize the 4th channel as the alpha channel, and react properly.

    If you import your PSD as a composition, AE will create a composition that matches your photoshop file, one layer each per layer of your PSD.

    Each layer will have it's own transparency, but the 4th channel (alpha) won't affect their display, and will effectively be useless.

     

    Do you have more than 4 channels in your .psd file?

     
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    Jun 17, 2009 8:46 AM   in reply to aljCharlie

    When you import the merged photoshop file into AE, and you select it in the project window, right-click on it and choose "Interpret Footage".

    Does AE recognize it as having an alpha channel? Is the dialog box set to "ignore"?

     

    Also, just to make sure...this isn't a case of the background color of your comp matching the background color of your source file, is it?

    Have you tried viewing your comp with the transparency enabled (little checkerboard-looking toggle button at the bottom of the comp window)?

     
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    Jun 17, 2009 9:04 AM   in reply to aljCharlie

    Can you post your photoshop file somewhere for us to download and test?

     
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    Jun 17, 2009 10:04 AM   in reply to aljCharlie

    It works perfectly fine for me...

     

    First, here's a picture of your alpha channel in Photoshop (white areas being opaque, black being transparent).

    Picture 1.png

     

    Next, here are your import settings for the PSD within After Effects:

    Picture 2.png

    With the item selected in the project window, this is the information that should display at the top of said window:

    Picture 3.png

     

    And, here's a picture of the image in a timeline, showing the transparency (successful alpha composite):

    Picture 4.png

     
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    Jun 17, 2009 10:54 AM   in reply to aljCharlie

    Strange.

    I see you're using CS4.

    I'm still on CS3 here. Have you tried running the updater to see if you have all available updates?

    Also, try saving your file as a .tif, or a .tga (with alpha channel) to see if that works instead.

     
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    Jun 17, 2009 11:21 AM   in reply to aljCharlie

    I have to concur with Charlie. I couldn't get it to work, either. Seems like we have found ourselves a very specific bug that affects the Windows version only... *sigh*

     

    Mylenium

     
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    Jun 17, 2009 11:40 AM   in reply to Mylenium

    Just tried it on my laptop (Mac - AE CS4), and I couldn't get it working either.

    At first I thought it may have had to do with the color profile, or some weird reaction to the frame size/resolution from the PSD, but even swapping that stuff around had no effect.

    One thing that I noticed between Photoshop CS3 and Photoshop CS4 (though it should have no affect on the file) is that the shortcut keys for soloing channels have changed.

    Instead of tilde, 1, 2, 3, and 4, they're now 2, 3, 4, 5 and 6.

     

    So, it's reproducible in CS4 on a Mac and PC.

     
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    Jun 17, 2009 1:17 PM   in reply to aljCharlie

    I am not sure this a bug.

    It could be. But note that I can produce an identical case in which this behavior is not a bug.

     

    The thing is, in the world of video applications, Alpha Channel means "fourth channel used to store transparency values".

     

    In Photoshop, it normally means the same thing, but it can also mean "arbitrary channel created and stored for whichever reason the user may want it on the future". Typically, to save a selection so that it can be retrieved later. In fact, you can have many of these arbitrary channels.

     

    So, imagine this scenario:

     

    1. User makes a selection of the outline of the house.

    2. Instead of cutting the pixels outside the house, or creating a layer mask, the user goes to the Channels panel and hits the "Save selection as channel" button (or equivalent menu command).

     

    Photoshop creates a fourth channel (or even a fifth or a sixth if there were additional channels already), which is called "Alpha" but the user never did anything to make the information in that channel produce transparency.

     

    If after making the selection, the user would have cutted pixels or created a layer mask, then that operation would be relfected on what we normally consider as Alpha channel.

     

    In this case, what you can do is go to channels pannel, control click the thumbnail so that the channel is loaded as selection, then create a layer mask (Layer > Layer Mask > Current selection) from that selection. That's it.

     
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    Jun 17, 2009 2:03 PM   in reply to Adolfo Rozenfeld

    Yeah, but that's not the relationship behavior that PSD files and AE have had for years.

    Agreed that Photoshop's channels are a robust and excellent way to store selections, but it has consistently been in the past that the 4th individual channel in an RGB file will get interpreted as the alpha channel.

    Also, the fact that it works that way for CS3 will throw many people off without accompanying documentation notating the change in operating procedure (i.e. the PAR differences between pre CS4 versions and CS4).

     
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    Jun 17, 2009 2:19 PM   in reply to TimeRemapper

    Steve: Creating alpha channels manually in PS has always been the way for file formats which do not handle transparency automatically. AE always did and still does handle the alpha channel in such a way for, say, Targa files. I just verified this in CS4.

     

    For PSD files, I don't think it's correct to read transparency from a channel which is not linked to transparency values in the PSD file. Transparency is automatic anyway. Bear in mind that a long time ago Photoshop didn't have the arsenal of non-destructive, transparency-related tools it has now. Like layer and vector masks, for instance.

    I don't have CS3 installed right now to test if an arbitrary channel in a PSD file was handled differently in that version, but we can try later. I can then try to find out if there was a change in behavior.

    Still, doesn't sound like a bug, since that would mean AE renders the PSD file differently from how Photoshop does it, which is perhaps the ultimate goal.

     

    The important part is that, in this particular case, it's all a matter of making sure the information in this channel is loaded and applied as an operation that produces transparency.

     
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    Jun 17, 2009 2:34 PM   in reply to Adolfo Rozenfeld
    AE always did and still does handle the alpha channel in such a way for, say, Targa files. I just verified this in CS4.

     

    That's why I mentioned to the OP to try that method...as a result we also observed the normal working behavior.

     

    I'm just saying that it's not acting like it did before, which is what the OP was also surprised about.

    If you don't believe it to be a bug, that's fine.

     

    Personally, I rarely rely on a layered PSD file's alpha channel information to determine transparency.

    I rely on the layer's transparency. That would be why I'd use a layered PSD to begin with.

     

    Otherwise I'd use an image sequence, or movie that had an embedded alpha.

     

    I think we're saying 6 of one, half-dozen of the other.

     
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    Jun 17, 2009 10:03 PM   in reply to TimeRemapper

    Ok, I tried a PSD file with a non-transparent alpha channel in AE CS3 and, yes, there seems to be a change in behavior for CS4.

    While I think the behavior in CS4 makes sense (again, for PSD files, since transparency is automatic), I'll try to find out more.

     
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    Jun 18, 2009 10:29 AM   in reply to aljCharlie
    I agreed. There needs to be documentation otherwise it's a bug and not a "feature". The fourth channel in PS has always been working as an alpha when imported into AE, why the change now if it's not a bug? Even if it makes more sense, why make a user have to do one more step before it works in AE when we don't have to do that in previous versions? It only means Adobe is pushing people to use other format such as Tiff and Targa and not PSD when it comes to importing alpha channel into AE.

     

     

    Oh, boy...

    Regarding change of behavior or bug, I didn't receive a confirmation yet so I can't say anything definitive at this time.


    As for everything else, and as Steve and I agreed, creating manually an alpha channel is an *extra* step you don't need to do at all.

    Regardless of "change of behavior vs. bug", this is what PSD (and also PNG, for instance) offers that the other formats can't offer - automatic transparency, you don't have to create manually an alpha channel to store transparency, because PS does it automatically for you.

    Again, you create manual alphas in TIFF and Targa files because they don't do it for you. Why would you want to pick a format so you have to perform an extra step, as opposed to not having to do it at all?

     

    Agreed, if there was a change in behavior, it should be clearly stated. If it's a bug, it should be fixed

     
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    Jun 18, 2009 8:34 PM   in reply to Adolfo Rozenfeld

    Just to close the loop (remember, a lot of people may read this thread in the future), here's what I found out about this:

     

    It turns out this not a change in behavior in CS4. And It's not a bug - In fact, it's more of a bug fix.

    Versions prior to CS3 didn't bring a non-transparent, user-created PSD channel as transparency (for all the reasons discussed above, and others). And CS4 just restores that. In other words, it's the way AE always handled this.

     

    If you would like to have more options when importing a PSD document with non-transparent alpha channels, please file a feature request.

     
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    Oct 19, 2010 10:28 PM   in reply to aljCharlie

    I am not sure if the problem still happen with CS5 but in CS4 there is this problem with AE not reading .psd's 4th channel.  FYI I am working with image sequences coming for a 3d app and we rendered out .psd files but when we import the image sequence AE does not read the alpha. But if we open the psd file in photoshop it is clear that the alpha does exist.  working on a mac.  Our solution was to turn all the .psd files to .tga files and that was our workaround.  Hope this helps... but it does not solve the .psd issue.

     

    hope this helps

     
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    Oct 19, 2010 10:41 PM   in reply to n.puertollano

    As explained before, an alpha channel in PS is a way to store a selection. It's not mapped directly to transparency values, as the video apps/files usually imply. The problem is, if AE behaved the way you mention, a lot of PSD  fileswould come in incorrectly, as the user created those channels to store selections, not to produce transparency. What would happen, for example, in the many cases where there are 2, 3 or 10 "alpha channels"? Bear in mind that PSD files always record transparency values automatically, so  there is no need to save an alpha channel to begin with. If the 3D app didn't create transparent pixels, maybe there's a different setting for that.

     

    Saving it as TGA "fixes" this for you because Targa files are originally video-specific and they only can contain a fourth channel to store transparency.

    Of course, if you want a way to turn discreet channels/stores selections in PSD files into transparency, please file a feature request.

     
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    Oct 19, 2010 10:51 PM   in reply to Adolfo Rozenfeld

    Thanks Adolfo I understood your last reply.  What I meant to say was for anyone still having this issue the solution is to use tga or tiff files.  This is good to know cause I teach AE and I used to say that it was ok to save .psd sequences at least now I can change that process and explain why.

     

    --nico

     
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    Mar 6, 2012 1:01 AM   in reply to aljCharlie

    Well, I know this is an old post but I just ran across this issue while exporting an image from a 3d render which exported the alpha as a channel insted of as a layer, but I found a solution if anyone arrives here through google as I did while investigating on this,

     

    1.-Open your .psd, go to channels, select everything but the alpha channel, delete them,

    2.-Save this as a copy of your file

    3.-Now you get two different files, your RGB and your Alpha (the copy you just created), which you can import to AE and use it as a matte.

    Pretty simple, now, if this is an image sequence, just record an action of the previous steps and run it as a batch process in photoshop with all of your frames.

    Also works with multipasses, (In my case, I also had an z-depth pass from my 3d render as a channel)

     
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