Similar questions have been asked before, but they all date back 2 or more years.
I frequently use ImageMagick in a 3D animation pipeline to convert EXR files to other, smaller formats. Specifically using Pixar RenderMan to render the final images. These images most often contain multiple channels that are then composited to form the final image. However, they also include a so-called "beauty" pass, which is the combination of these channels/passes.
I have managed to render out EXR files that simple contains the "rgb" and "a" channels and these are converted to PNG without problems. Without the extra channels/passes, though.
Now, RenderMan technically refers to the "beauty" pass' channel as "Ci", and this seems to confuse ImageMagick, though it is RGB. So "Ci.R" etc. I could rename this to "rgb" instead of "Ci", which works, but breaks other tools like RenderMan's denoiser.
From what I can tell it isn't possible to tell ImageMagick to look for the "Ci" pass and use it as normal RGB.
I should note, that trying to open this image in Photoshop also just shows up black, so ImageMagick is not alone. However, Nuke correctly identifies the right channels. I don't know if the OpenEXR format somehow specifies which channels should be used as RGBA by default.
List of channels that should be present in the first sample file:
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Ci a specular_mse albedo albedo_var backward diffuse diffuse_mse forward mse normal normal_var specular zfiltered zfiltered_var
16-bit EXR straight from render with all passes: https://www.dropbox.com/s/mx9phk5ihox17 ... e.exr?dl=0
16-bit EXR with no AOVs (saved using Pixar "It" tool): https://www.dropbox.com/s/a7ponb8df62ah ... s.exr?dl=0
16-bit EXR after denoising: https://www.dropbox.com/s/xh6herwpnr9vu ... d.exr?dl=0
8-bit PNG of what it should look like: https://www.dropbox.com/s/t930v6zb7blvh ... s.png?dl=0
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Version: ImageMagick 7.0.8-49 Q16 x64 2019-06-08 http://www.imagemagick.org Copyright: Copyright (C) 1999-2018 ImageMagick Studio LLC License: http://www.imagemagick.org/script/license.php Visual C++: 180040629 Features: Cipher DPC HDRI Modules OpenMP(2.0) Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr lzma openexr pangocairo png ps raw rsvg tiff webp xml zlib