ACR: How to Channel Swap DNG Files for Infrared Processing

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  • Updated 5 years ago
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Infrared photographers like to switch the red and blue channels, however Lightroom has never had a channel mixer, so typically we have edit in photoshop to use the channel mixer, and even though this can be automated, it has one major drawback, the channel swapped image is no longer in RAW format... so the problem is you need to try to get the white balance right first, but you are not looking at the image the way the colors will be once you do the channel swap. Well, I've come up with a unique solution to this, it allows you to effectively switch the red and blue channels of the DNG file itself without actually changing ANY of your raw data, and allowing you to continue to work with the file in lightroom with all the benefits of working with raw data in a DNG file. I have a few blog posts explaining how this works and how I am integrating it with Light Room 5

http://jamesrichters.zenfolio.com/blo...

http://jamesrichters.zenfolio.com/blo...

I have two questions about this... first of all, is there a way to change the metadata tag 'SubIFD:CFAPattern2 ' directly in lightroom 5? I basically want to switch the 0's and 2's here

Also, MOST of the time when I do this, it works fine, however once in a while, I'll go work on an image that has the CFAPattern changed, and it will revert back to the original colors, but if I zoom in on it, it's back the way I want it. I think this is because LR5 is using preview data to speed things up. I have tried discarding 1:1 previews then building 1:1 previews, but the problem persists... Often it will say 1:1 previews already exist, so it doesn't build them.. even though I just THOUGHT I deleted them! I would like to know if there is a way to remove ALL preview and jpeg information from my DNG file so it's forced to re-build all new previews based on the CFA pattern I have changed?
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James Richters

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Posted 5 years ago

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Rikk Flohr, Champion

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Metadata>Update DNG Preview & Metadata
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James Richters

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Thank you very much, this is exactly what needed to be done! I was stuck looking under Library > Previews and didn't think to look anywhere else.