CGTalk - Using actions to create texture/alpha map quickly in PS

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Fanko

10-25-2009, 08:04 AM

I was watching Chris Stoski training video and he mentioned he uses Actions called MULT_n_FLATTEN to quickly create alpha map and texture map to be input into Maya for camera mapping to cut out the texture map. I was wondering anyone knows what script he actually used there in the Action? The most important thing I need to know is how he make the edge of the pixel bleed slightly over the alpha map to avoid black matte fringing.

many thanks for helping

stevocreative

03-06-2010, 06:58 AM

I saw your post a while ago and was interested in the same subject. Since then I've been looking into various other issues relating to this and "linear workflow". It seems the answer to this particular problem is to buy the Photoshop plugin called ProExr.

Your image needs to be in 32 bit (float) mode.
Then save it out as a .exr file using proExr.
Then re-open the file in Photoshop whilst holding down the Option key.
Choose the "UnMultiply RGB using Alpha" option.
The image will open with two layers, one for the image and one for the alpha.
Convert the "alpha layer" into a proper alpha and then delete that layer.
Save the file.
That's it!

I'll post some more info on these kind of issues when I get time.

If anyone has some better ideas please let us know.

everlite

03-06-2010, 03:25 PM

He simply made an action that multiply's the layer and merges them together. Look into creating photoshop actions, its very simple. You just hit record and do the process, stop and save it.

The whole EXR thing is a little overkill. You dont need to use exrs for projections. Only use exrs when you need high lighting range, hdrs ..

Dave.

stevocreative

03-22-2010, 04:44 AM

Thanks evelite.

I tried creating an action after I'd seen the DVD, figured that I wasn't getting enough opacity and gave up.

Having read your post I had another go and it works. My action makes four copies, merges them and then copies it four more times and merges again. So ultimately it increases the opacity of edge pixels 16 times, which seems to work fine.

I'll attach my action to this post for anyone interested. You need to select the relevant layers which it then merges together before deleting the others. It also creates an alpha channel. If there isn't more than one layer to merge, or if there aren't any layers to delete it will return an error message.

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