PNG with alpha channel - Compositing problem

[gerbilho]

Hi

My usual workflow in vray is to save the rendered image to png with alpha channel. This makes it easy to open in photoshop and have a transparent background to apply a sky. In vray I renderd the final image with a black background so that in photoshop I could get a perfect edge by removing the premultiplied pixels with remove black matte.

In corona this workflow doesn't work as you can see by the attached images. Remove black matte leaves a white edge around the image.
What is the best workflow for this kind of situation in corona?

Thank you

[racoonart]

In my opinion everything with alphas in photoshop is fu**ed up anyways (especially when you need "remove black matte", which is total nonsense) but I understand that it should be at least working as good as with vray output.

Could you post the 2 pngs here - one vray, one corona? That way it's easier to find the problem

[gerbilho]

In my opinion everything with alphas in photoshop is fu**ed up anyways (especially when you need "remove black matte", which is total nonsense) but I understand that it should be at least working as good as with vray output.

Could you post the 2 pngs here - one vray, one corona? That way it's easier to find the problem

I have yet to post those two images for comparison.
I found an alternative method: saving the images in tga and the removing the background in photoshop using the alpha channel.
If I save as tiff and remove the alpha in PS I get the same problem as with png. Only tga is working for me.

[theOrzel]

I found an alternative method: saving the images in tga and the removing the background in photoshop using the alpha channel.
If I save as tiff and remove the alpha in PS I get the same problem as with png. Only tga is working for me.

Can you post a TGA file screen shot? I made a small test and I see no difference in blending with .png, .tga or .tiff (only PS remove black matte messes up, but that's what DeadClown mentioned ). I'm bit confused because I've never experienced such compositing problem.