Photoshop/shake Workflow Difficulties

[user_deleted]

Hey,

I'm trying to take a regular 8 bit photoshop file, no lookups/curves/ICC profiles on it, and recreate the layering that was done in photoshop within shake. Say I only have two layers, a solid bg color and then a fg circle of a different color that is semi transparent. When I save out the file (using .tif) from photoshop and bring it in, this does not match the composite created in shake from the circle that is multiplied by the transparency matte and then put over the bg color.

Has anyone experienced this problem? Have you guys tried this and had it fail.

I've tried various different things from saving the matte out separately, different file formats, saving with and without transparency from photoshop, saving as copies, etc but ultimately I believe there is a math difference between photoshop and shake. Photoshop has transparency built into the color channels while shake uses only the alpha.

Any advice would be greatly appreciated. Thanks.

[joojaa]

Well, its one thing photoshop is a bit weak on. See the developpers of photoshop consider alpha interpretation as a no issue. However its a HUGE issue. Unfortunately photo shop doesn't make it easy to KNOW what alpha interpretation it is exporting. SO while alpha is allways straight inside photoshop, its not necceserily straight once photoshop saves the information out it is in fact most likely to be premultted even tough it APPEARS straight in photoshop. And they neglect to tell this to you, because they think photoshop is the end of the line for the picture.

Fortunately switching between premultted and straight alpha is quite easy. It is quite literary a division/multipliucation operation. You can do this on either end.

To discern what you have is easy if you have a bright halo and jagged edges its straight but your using premultted, if it has dark halo around its premultted and your using straight.

[user_deleted]

if i recall correctly in the multilayer node there were blending options that specifically mimicked the photoshop blending modes. there was also an opacity and PS opacity option that should sort you out.

[aaron-marine]

yeah i import stuff from PS all the time. If you are using the layers imported separate from each other, you will want to make sure in the prefs for each image you turn on auto alpha. Also what i learned from the Shake DVDs from gnomon is that by putting and mDiv followed by a mMult node, you will clean up any incorrect mult problems. then just use the multi layer node to adjust blend modes and everything should look spick and span.

you know if you go to file>import photoshop you can bring in the layers all together setup in the original psd format you saved it in right?

even if you do know that, it is best to double check each of your layers for the things i specified a little bit ago. hope that helps