Image Texture Node, Clip Image

Question

I would like to make a decal in Cycles.

When I use Clip in the Image Texture Node then the background is black. I would like it to be transparent.

The manual (https://docs.blender.org/manual/en/dev/render/cycles/nodes/types/textures/image.html) says: Clip "Clip to the original image size and set all the exterior pixels values to transparent black."

What the hell is transparent black? Is it black or is it transparent? How do I get the background image to show through the "transparent" black?

This is my setting:

Maxx, like this? That makes the Logo Black. The Image has no alpha information.

Answer 1

A color has for components : red, green, blue, and alpha. Transparent black would be 0,0,0,0. The image texture node outputs red, green, blue in the first (yellow) output and the alpha in the second (gray) output.

If you want your surface in cycles to be transparent where alpha is less than 1, combine a transparent shader with your current shader with a mix shader node, and use alpha as the factor. (current shader in the second input, transparent shader in the first input).

Answer 2

I did not get it to work with the transparency shader but it seems to work when I just attach the Alpha of the Logo (although it has no alpha channel, I believe - it is just a jpg) to the Fac of the Color Mix Node.