I'm mapping a plane with an image, but I need to make the background of this image transparent. I try some tutorials with layering in the texture room, make decals, but they always use a background color at the end. I need to have transparency in the background. I manage to get something similar to this. but when I set my scene background color to white, I have some problems. is there any simple and basic process for this? when I uncheck the transparency in my render, the color of the image apear ok, but the transparency is needed. Also I'm, not sure if I need to use a layer over my plane. I'm using carrara 2.

aolba, If this is the shader tree you are using, ditch the opacity layer. This is only used if you are creating a decal-like layer on an object. It will not make the rest of the plate transparent. Keep shader one ("Whole Object" at the top of the tree) the same, but check the box at the bottom that says "No Light Interactions When Fully Transparent". This is very important as it will make your plane transparent. Take your opacity map and put it in the transparency channel with your color texture map. Invert the color of your transparency image as the transparent parts need to be white. Check the box at the bottom that says "No Light Interactions When Fully Transparent". Once again this will make it truly transparent in those areas you want it to be. Check it out and see what happens. Ken  ps My version of the shader tree is above.

Thank you. I copy the setting I see and yes it looks better. Since my background is white it looks fine. But I make a test with blue and it does'n look so clean now. I have to make a test with a new image, may be that's the problem.

Not a problem, The problem with your blue image is with the anti-aliasing on the transparency mask. You need to eliminate anti-aliasing in the mask. the easiest way to do this is to create the mask with as clean lines as you can make. Also you may want to avoid using a JPG file format. The compression algorithm usually causes artifacts like what you are seeing. Try a BMP, TIF, or GIF with only 2 colors. The last is probably your best bet as the GIF compression makes for smaller file sizes and the two color motif allows you to be VERY selective on your transparency. Let me know if you need any more help! Ken

Oh, yeah, here's an image that will show you. The line on the left is with anti-aliasing, the right, without. JPG images are more likely to keep the antialising intact. Now in extreme closeup renders (lower images) you may see the stairstepping of the aliased (left) one, but increasing the resolution will help to prevent that. Ken

OOPS forgot the image... Sorry! Ken