Can Pix4Dmapper correct for color distortion in raw images?

PIX4Dmapper
1

Hello-
I’ve received a few datasets (jpgs) from drone cameras that I need to orthorectify. They were flown in the spring over forested/clear cut areas, which were very green at the time. The green seems to have a lot of yellow in it, and when we compare these photos with photos in our base map, the colors look unrealistic. Screenshot 1 contains the Pix4D ortho - very bright green. Screenshot 2 is an ortho created from a different camera & software, which has realistic color.
Does Pix4Dmapper have tools I can use to adjust color in raw images or match RGB values from other photos?
I understand that modifying raw photos with PhotoShop or other software is not advised before processing in Pix4D.
Thank you,
Anne
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2

Hi Anne,

PIX4Dmapper does not have a tool to directly adjust colors in images. You can try using the mosaic editor for better results, the article: Color Discrepancy for Edited Regions in the Mosaic Editor can help guide you with this solution.

Any RAW images will need to be processed to either .TIFFs or .jpegs. for them to be used with PIX4Dmapper. Using 3rd party software to batch color correct the RAW images could be used. However, with this issue mostly revolving around the color difference due to vegitative state in different life cycles. If you were to correct the vegitation to match, in theory, any other features that are not vegitative will be adjusted as well, thus potentially moving the problem elsewhere.

It should be noted that 3rd party editing software can erase and/or change an images metadata, and should be used with caution.

I hope this helps. Also, if you could post anysample results to the community, that can help focus efforts as well.

Thank you,
Jonathan

3

Jonathan-

Thanks for your reply.

The color distortion covers such a large area of the dataset (90% of the photos) that correction in the ortho mosaic editor wouldn’t work.

I’ll experiment with correcting the color in a 3rd party software, although I am concerned about the exif files being removed during that process.

Thank you.

Anne

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4

Hi Anne,

Working with backed up datasets and knowing the potential metadata issues should aleviate any concerns. Would love to hear how the results come out if you have the time and are able.

Thank you!

Jonathan

5

I was able to use PhotoShop to adjust the exported ortho using these steps:

  • (First make sure you have the .tfw associated with the ortho as PhotoShop will destroy any internal georeferencing.)
  • Load a photo with good color balance into PhotoShop.
  • Use the Image/Adjustments/Match Color tool to save the statistics from that photo. It creates a .sta file.
  • Open the photo needing adjustment and use the Match Color tool to load the statistics that were saved from the first photo.

This works for us because we have base imagery for the sites that we can copy the statistics from.