Opening PSD applies alpha channel

[mecdos]

Hi,

I have a few renders with alpha channels saved as PSD. I used to be able to open this files just fine - the background would open without transparency and then i could use the alpha if i wanted to to create transparency. But now upon opening the file, the alpha is applied to transparency, the alpha channel is gone and i lose the information in the transparency.

how do i open the files without transparency?

i can open them in other applications like Preview, and it displays correctly, then i can copy and paste back into photoshop but that's just ridiculous. also placing images into illustrator show up with alpha applied as transparency.

[JJMack]

The Photoshop Background does not support transparency it can not be masked.  Some features  in CS6 and newer version of Photoshop may automatically convert a background layer to a normal layer if you try to mask the background layer. You can see in CS2 the background layer is locked and menu layer>Layer Masks items are grayed our.  I have to convert the background layer to a normal layer to mask it. If the bottom layer has transparence and not layer mask it sounds like your masked layer was rasterized which removed the layer  mask channel and delete the masked pixels.  I have never seen Photoshop do that on its own.  However I have see sctions and script rasterize layers.

[mecdos]

yeah i understand that, but that's part of what's happening. the background layer is turned into a regular layer and it's still called "background"

[c.pfaffenbichler]

A possible work-around might be using Layer > Layer Mask > From Transparency.

And quite frankly I suspect the rendered psd have actual transparency instead of an Alpha Channel, psd being an »Adobe file format« it seems likely Photoshop interprets it correctly and Preview might not … mind you, I could be wrong.

[mecdos]

c.pfaffenbichler wrote:

And quite frankly I suspect the rendered psd have actual transparency instead of an Alpha Channel, psd being an »Adobe file format« it seems likely Photoshop interprets it correctly and Preview might not … mind you, I could be wrong.

i'm sure it has alpha and not transparency because otherwise preview wouldn't be able to throw away the transparency without it defaulting to white or another flat color.

[c.pfaffenbichler]

What seems strange (but difficult to assess) is that in the opened psd I can discern no structure in the shadow the sphere throws.

[mecdos]

i hadnt noticed. Ill check in the morning. I put that scene together realy quick to demonstrate what i was talking about. On the tiff i ran auto hdr tone mapping and thats probably why you can see detail in the shadow. i cant do the same adjustment on the psd file because the image is mostly empty so the auto correction comes out awful.

Edit. the detail in the shadow is the same. just can't auto correct it to display right

[JJMack]

te_co wrote:

The background layer is turned into a regular layer and it's still called "background"

Yes you can do the in Photoshop.  Here is a  document that never had a Photoshop background layer it however has 7 normal layers named background none have any transparency soonle the top most layer with its visibility on is visible in the composite view.

This Background layer never had a layer mask.

[mecdos]

oops, my memory failed, the behavior i remembered was for TIFFs

TIFFS retain the alpha and the background while PSDs always applied alpha to transparency.  But in Preview it's the other way around. the TIFFs open transparent, and PSDs ignore alpha.

PSD preview

PSD opened

TIFF Preview

TIFF Opened

i guess i should be rendering to tif from now on. as i'm able to apply hdr toning without destroying my alpha information.