I have an image rendered, and its showing in the Blender Render window. In the compositior, i have a file output node set up to write out .tif files for each render pass. Can i somehow execute just the node tree without having to re-render my image?

Ok, so the proposed answer said: "Delete the renderlayer node from the node setup, and then blender won't render the 3D scene."

Feeling stupid here, but, if i remove the renderlayer node, then my file output node won't have any inputs anymore. It's direclty connected to the passes of the renderlayer node to output each pass as a .tif file. Secondly, what button do i have to press to then execute only the compositor nodes??

  • $\begingroup$ possible duplicate of render only composite $\endgroup$
    – p2or
    Jul 13, 2015 at 14:52
  • 1
    $\begingroup$ For that kind of workflow your'd be better off rendering to OpenEXR format, so that you can save all the layers in a single file. $\endgroup$
    – user1853
    Jul 13, 2015 at 17:04
  • $\begingroup$ I know i could render to an OpenEXR file. But what if i want to have seperate .tif files? So i have just finished a very long render. Unfortunately, i forgot to check "Compositing" in the Post Processing. That means, my render is now sitting in the image editor, but my file-out node was not executed. What now? Do i have to start my 2 hrs render again, only to execute the file-out node?? $\endgroup$ Jul 15, 2015 at 19:31

2 Answers 2


If I understand your question, when you render an image and set "use nodes" in the compositor, you can check the "backdrop" function, then Ctrl Shift click on a node to create a viewer and see the output of that node on the backdrop. You can see the result anlso in an UV/image editor, if you change the header's dropdown menu from "render result" to "Viewer node".

As soon as you change a value in the compositor, the change is reflected in the Viewer (Backdrop or UV/Image window), without any need to push any button to trigger the compositor, and without the need of redoing the render: it's automatic (maybe a little slow and not realtime: check the upper info header for a compositing Time bar)

  1. Render your complex scene as images to a PNG file sequence with some file name sequence such as base name sequence001. No compositing. The idea is multiple compositing nodes will be used later.

  2. In a separate scene, for convenience, use the compositor, read in the file sequence001. Composite these images in the compositor. These newly composited files can be written as base name sequence002. You might put some non renderable text object in the scene such as "See the compositor" as a form of notes. Otherwise this blender scene might have very few objects.

  3. Repeat step 02 if necessary to achieve your goal.

  4. The assumption is that your compositor nodes are doing more the the Blender VSE can.


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