matte and png , lines around objects

[marq]

Hi

Im rendering some matte objects and exporting them as png(the only way i know) for composition in photoshop. The thing is that the objects and shadows come out with an edge around their contour the same color as the background, How can i avoid this? I dont know if this is a matte or an antialiasing problem or something else. The objects have alpha contribution to -1.


thanks for the help

marq

[egz]

In photoshop select the layer, and use the Layer > matting > remove black matte option to remove the premultiplied background color. That is if you rendered it on black.. Photoshop only handles black and white backgrounds. After effects, combustion etc can remove any color.

[franzISKA]

ahoi!!!

i think it is another problem...

try this:

customize - preferences - rendering - (background) check "don't antialias aginst background"

i think it should do it...

so long

[egz]

Why would you not want anti aliasing against the background? Unless you are producing content for something that does not support alphas at all, there's no need to use this.

[marq]

Thank you!

the remove black/white matte option in photoshop was exactly what i needed. I would have never found it myself because i have photoshop in spanish and the word "matte" is translated as "halos".

seems like software translation is like movies translation which is a very funny thing when you know both languages

marq

[nully]

the aa effect around transparency creates a white glow effect - not good if want a background with a dark colour

[egz]

Nully: not if you do it the right way and remove the premultiplied color in either photoshop or your compositing system. Or save with a straight alpha. It's not really a problem as long as the footage is treated the right way.

[k-arts]

how would i solve that edge in fusion?

cheers

Liz

[Seraph135]

how would i solve that edge in fusion?

I'm not quite sure what issue your trying to solve...However, if you want to un-premultiply your renders stick a channel boolean after the loader. Set its operation to "divide" and then put "Alpha FG" into the R,G,B channels and set alpha to "Do nothing". This will give you a white background where your background in max was black, but later when you pre-multiply again it will go away and be fine.

If you rendered on a color other than Black and want to fix it you have to first pipe the loader into a channel boolean and set the operation to "negative". Then for RGB set to "Alpha FG". This will put the Alpha into your RGB channels and invert it. Then take a BG node and sample the color from your loaders background. Multiply the BG node over the channel booleans result. Take the result of that and using another channel boolean subtract the result from your original loader. The result of that will be your render pre-multiplied on a black background. Kinda complicated and I'm not able to upload a sample image right now. Let me know if it doesn't make sense and I'll upload something later.

Tim J

[SonOfNimrod]

hey, handy hint....i use png format a lot too...=)