--render-format EXR saves as multi-layer EXR #54311

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Sybren A. Stüvel · 2018-03-13T18:41:41+01:00

Sybren A. Stüvel commented

2018-03-13 18:41:41 +01:00

Commit 2a097527f2 changed the way EXR files are written, in a way that breaks loading & inspecting their size in Python.

To reproduce:

Get this blend file exr_save.blend
Render it with blender -b exr_save.blend --render-format EXR -o 'demo-###.exr' --render-anim
Open exr_save.blend regularly (so no background render) and run this script from the text editor:

import bpy

i = bpy.data.images.load("//demo-001.exr")

print(50 * '=')
print('Image type (1): %s' % i.type)
print('Image file format: %s' % i.file_format)
print('Image size: %dx%d' % tuple(i.size))
print('Image type (2): %s' % i.type)

2a097527f2 outputs:

Image type (1): IMAGE
Image file format: TARGA
Image size: 0x0
Image type (2): MULTILAYER

As you can see, the image is recognised as MULTILAYER, even though I specified --render-format EXR and not --render-format MULTILAYER.

Now build the preceeding revision ed72600 and follow these steps again (render in background, and run the script). It outputs:

Image type (1): IMAGE
Image file format: OPEN_EXR
Image size: 960x540
Image type (2): IMAGE

Here you see that we can actually get the file format we need.

Some background info: in Flamenco we use progressive rendering (e.g. rendering in Cycles sample chunks), which saves the chunks to EXR files and uses a blend file with a node tree to merge the samples. This blend file needs to be set up with the correct render resolution, which is taken from the EXR file. However, since this commit, we cannot do this as Blender doesn't report the image size for multilayer EXR files (#53768).

Commit 2a097527f20d changed the way EXR files are written, in a way that breaks loading & inspecting their size in Python. To reproduce: - Get this blend file [exr_save.blend](https://archive.blender.org/developer/F2440205/exr_save.blend) - Render it with `blender -b exr_save.blend --render-format EXR -o 'demo-###.exr' --render-anim` - Open `exr_save.blend` regularly (so no background render) and run this script from the text editor: ``` import bpy i = bpy.data.images.load("//demo-001.exr") print(50 * '=') print('Image type (1): %s' % i.type) print('Image file format: %s' % i.file_format) print('Image size: %dx%d' % tuple(i.size)) print('Image type (2): %s' % i.type) ``` 2a097527f20d outputs: ``` Image type (1): IMAGE Image file format: TARGA Image size: 0x0 Image type (2): MULTILAYER ``` As you can see, the image is recognised as `MULTILAYER`, even though I specified `--render-format EXR` and **not** `--render-format MULTILAYER`. Now build the preceeding revision ed72600 and follow these steps again (render in background, and run the script). It outputs: ``` Image type (1): IMAGE Image file format: OPEN_EXR Image size: 960x540 Image type (2): IMAGE ``` Here you see that we can actually get the file format we need. Some background info: in Flamenco we use progressive rendering (e.g. rendering in Cycles sample chunks), which saves the chunks to EXR files and uses a blend file with a node tree to merge the samples. This blend file needs to be set up with the correct render resolution, which is taken from the EXR file. However, since this commit, we cannot do this as Blender doesn't report the image size for multilayer EXR files (#53768).

Sybren A. Stüvel commented

2018-03-13 18:41:41 +01:00

Added subscriber: @dr.sybren