How to use masks or paste one rendered alpha image on the another rendered image


I am a noob user with post editing images. I don’t know what nodes to use when adding one alpha rendered image on the another rendered image on Blender post processing (compositing). How do i combine these? Or how do I use masks as well here? For example if I have a rendered wall, where is a window but I want to change a scene behind the window. I fell lost if I can’t find a proper tutorial about these things. Thank you in advance.

I’m a noob too. I’ve been watching some few Blender pro users on Youtube. Dayum, they got pretty good tutorials to search for and get good pointers. For instance, check out this guy’s Youtube channel.

Thank you, that’s useful. But that’s not really answering to my question that how do I combine one rendered alpha image on one rendered? I have tried use mix node in combining these two, and then put the “string” to composite node. In photoshop you can just use layers for combining images but how do I do it in Blender?

…gives you this…

(Note: the final image was rendered with transparency, but the upload got converted to jpeg.)

Is this what you’re looking to do?

Alpha Over node is the blender equivalent to basic layer on layer in PS.

Hi, thanks. What scale node does in this case? I would think of using mix node or something that combines those two instead of using scale.

I am trying to render a realistic looking images, a view from a room, where is a window with different sceneries of it

Pal, look at it. The Scale nodes do exactly what is written: the images are scaled to fit the Render size. They’re used if you want to conform them to the same size as your final render.

In your case, put your room image where my star image is, put your scenery where my sparks image is, hit F12 and MAGIC HAPPENS!