PSD files display alpha channel selections instead of composite image

[DavidOfMA]

I save my PSD files with the image preview so that Windows and, I thought, IMatch would display the whole image, even when I have saved selections and fragments of images in the layer stack. But instead, IMatch displays only part of the image, outlined by the saved selection. Is there some way to get IMatch to only display the preview image or, alternatively, to process all the layers when it creates the thumbnail, so the full image is displayed instead of only a selection? The Viewer also displays only a selected part of the image.

Attached is a screenshot. The white space in the thumbnails that have large white areas should be filled with image, as in the JPG files beside them and in the PSD files themselves. Sometimes the parts displayed were created in the PSD files by making a selection and then selecting "Layer via Copy". I see the same effect when the file has saved selections, which become alpha channels. IMatch displays the part of the file the alpha channel selection selects, instead of all the layers.

NOTE: I tried creating a reduced-sized version of one of these files to upload here, but unfortunately the resize operation changed it somehow, so IMatch displays it properly even though it has the same layers and masks and saved selections.

David

[attachment deleted by admin]

[Mario]

IMatch cannot analyze layers. Adobe closed the formerly open Photoshop format with version 6, stopping to document it. IMatch only ever looks at the preview/composite image, at least that what's in the docs of the image library. It also interprets the alpha channel so users who have PSD files with knock-out backgrounds can see this properly in IMatch. If your files have multiple alpha channels, paths and whatnot, the alpha channel may be messed up and will only show right in PS.

Sometimes the alpha channel is also not really matching the image, which does not fool PS but applications which use the preview and the alpha channel. As you have learned, re-saving the file after a small change sometimes fixes this because PS re-creates the composite and alpha channel. By definition, the composite and the alpha channel are supposed to allow 3rd party software to show a proper rendition, but sometimes does not, especially when you have multiple alpha channels and masks in layers, paths, working paths and stuff.

[Ferdinand]

I see to recall that there's a similar problem with TIFF, which is a more-or-less open standard now owned by Adobe.

There is an option under File Format preferences for PSD and TIFF to use the alpha channel.  It's documented in the help file under Configuring Imatch | File Formats.  IIRC this option was introduced to deal with situations like David's.

[Mario]

Thanks. I didn't remember that    
The OP will have to rescan his files with the "force update" option after changing this option.

[DavidOfMA]

Thanks to both of you. That was, indeed, the problem, and unchecking "Use Alpha channel" for PSD files and doing a force rescan of a test folder restored the full display of the images.

David

[Ferdinand]

It's been a while since I looked at this, but I thought that there was some difference between TIFF and PSD in this regard, but can't recall now what it was.  I thought that PSD was less affected somehow, although that's not David's experience.  My research indicated that IMatch was not alone in having this problem.

IIRC it can also depend on what you were doing and how your layers / channels are ordered.  For example, if you were editing a mask when you saved the file, which is effectively an alpha channel, then you may get this effect.  I think saved selections are also involved, etc etc etc.

[Ferdinand]

Previous discussion on this topic:

https://www.photools.com/community/index.php?topic=3819.0

Also https://www.photools.com/community/index.php?topic=978.0