[jfrancis]

Or

2.

Put the alpha over the background. Invert it so it is a photographic negative. Set the blend mode to MULTIPLY

Then put the color over everything. Set the blend mode to LINEAR DODGE (ADD)

[jfrancis]

I'm sure there are better Photoshop-specific ways. I'm old school.

http://www.digitalartform.com/archives/ ... g_pre.html

[mashium123]

I...
or you can multiply the background by the inverted alpha and linear dodge the foreground
http://www.digitalartform.com/archives/ ... g_pre.html

that's the only method for me, that works competely without generating edges, in this given example.

[brodie_geers]

I'll have to give those methods a shot. Here's the method that was recommended to me by Tom, however, after I reported similar issues.

1. Open Render and Alpha in PS (in two separate PS documents, as opposed to 2 layers within the same document)
2. Change the Alpha to Grayscale via this method
Edit / Convert to Profile... / Destination Space / Grey Profile: sGray
3. Copy Alpha
4. Apply layer mask to Render
5. Alt+click layer mask to enter the layer mask
6. Paste Alpha
7. Click layer mask -> Apply layer mask
8. Layer -> Matte -> Remove Black Matte

The crucial part I was missing was that sGray conversion which made a huge difference. Without that, even if you removed the black matte (which is also a crucial step) the matte wouldn't be properly removed. It had something to do with an issue with photoshop as I recall. You can read the whole discussion here http://www.maxwellrender.com/forum/view ... 97&t=35111

Or, better yet, download this PS action which does these exact steps for you http://think.maxwellrender.com/-110.html

-Brodie

[jfrancis]

The crucial part I was missing was that sGray conversion which made a huge difference. Without that, even if you removed the black matte (which is also a crucial step) the matte wouldn't be properly removed. It had something to do with an issue with photoshop as I recall. You can read the whole discussion here http://www.maxwellrender.com/forum/view ... 97&t=35111

Or, better yet, download this PS action which does these exact steps for you http://think.maxwellrender.com/-110.html

-Brodie

Must be a 'color management vs no color management' issue.

I've seen that come up depending on how you use a channel.
http://www.digitalartform.com/archives/ ... photo.html

[jfrancis]

Also there is the “Blend RGB Colors Using Gamma:1” thing...

http://vimeo.com/14075970

[lsda]

We will try and come back soon. Thank you all so far.

[wigginsray2]

Does anyone know a good method for resolving this issue in After Effects? My Color and Alpha files are separate image files, and I've been cheating with doing a luma key on the alpha image and choking it a couple of pixels - but the accuracy isn't very good in some instances.

[wigginsray2]

I found a good way in After Effects CS5 using a variation of a solution posted previously.

1) Precomp the ColorImage and Alpha Image
2) In Precomp: put Alpha image above and set mode to "Divide"
3) In MainComp: put Alpha image above Precomp
4) In Alpha image add effect->Channel->Set Channels
5) In Set Channels: Source Layer 4 -> Choose Alpha image
6) In Set Channels: Set Alpha to Source 4's -> "Lightness"
7) In MainComp: set Precomp TrackMatte to "Alpha"

there it is. There may be a simpler way, but this worked out well for me.

[tom]

[wigginsray2]

thnx tom, that's exactly what I was looking for.

[tom]

http://www.maxwellrender.com/forum/view ... 15&t=28957

[rusteberg]

woohoo! balls!

[rusteberg]

I mean boobies!