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How to get pixel values of extra channels from an exr source.

Alexander Samsonov

September 01, 2015 14:25

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Hi.

Does anybody know how to get pixel values of extra channels?

To get RGBA values i can use sourcePixelValue(). But how about extra ones?

 

Thanks.

Alex.

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4 comments

• 0
  
  josh January 10, 2018 20:08

  I would also like to know this. I can get the source pixel but can't seem to figure out how to query the channel values.

• 0
  
  (Michael) Kessler January 10, 2018 22:24

  Hi Alexander/Josh,
  
  To accomplish this, you would need to create a second image reader and read it in as a second layer in your image and set the requested channels (you can use the `-select` on per-source arguments).  RV's focus is on real-time playback, so it actively optimizes down the channels it reads from EXRs.
  
  If you load your second reader and wire them together with a layer, you can then sample the second source (which points back to the same exr with a different channel selection) to obtain your other channels.

   

  Thanks,

  -Kessler

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  josh January 10, 2018 22:37

  Thank you for the response. If I wanted to know the pixel value from a layer. Would this be the same thing or is there something slightly different. Here's an example and I want to use "Layer0" to grab the pixel value. 

  Example:

  101-102@@@.exr

  - z

  - Layer0

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  (Michael) Kessler January 10, 2018 22:39

  Yes, that would be the same sort of setup.  At the end of reading in a file the processing graph is baked down into as many as 4 accessible channels, those can be channels from a particular layer, or just default channels, etc.