# Is it possible to composite a scene without rendering from the command line?

There are options to enable or disable the compositor, but is it possible to composite without rendering ?

./blender --background my_file.blend --composite-only \
--render-result-from-file my_render_result.exr \
--render-output my_file_output.exr


Setting bpy.context.scene.render.use_compositing allows us to enable or disable the compositor but I cannot find a good way to skip rendering.

The best workaround I have found is finding the layer with the least objects and only enabling that layer for each render layer in order to get the quickest render and then using a script like: https://github.com/armadillica/flamenco/blob/master/flamenco/manager/application/task_compilers/tiled_blender_render_simple_mix.template to add image nodes to simulate the render result.

Is there a better way to do this ?

• It shouldn't render as long as the compositor node setup doesn't read from any render-layer nodes. What would you expect to happen in the case a render layer is in the node tree and it needs to read image data from it? May 13 '16 at 12:08
• The any render-layer part is the hardest part. The use case for this is seperatable render / compo with any given *blend file. And I am becoming more convinced that a way to load the render-result from and exr would be the nicest way to handle this May 13 '16 at 12:22