Debayer with _VNG is buggy (Bug #2074)

Added by Pierre Chatelier over 12 years ago. Updated about 12 years ago.

Status:Done Start date:2012-06-21
Priority:Normal Due date:
Assignee:Ilya Lavrenov % Done:

0%
Category:imgproc, video
Target version:2.4.3
Affected version: Operating System:
Difficulty: HW Platform:
Pull request:

Description

When debayering an image, you can use cvCvtColor(..., CV_BayerGB2BGR) (and other flavors of RG, GB...)
You can also use the (undocumented) cvCvtColor(..., CV_BayerGB2BGR_VNG)

Since OpenCV 2.4.0 (and in 2.4.1 as well), some saturated areas are not handled correctly by the _VNG version
I have attached some files :
image-natural.png (the input)
image-debayered-normal.png (normal output with CV_BayerGB2BGR)
image-debayered-vng.png (wrong output with CV_BayerGB2BGR_VNG)

Do not pay attention to the "blue" or "dotted" aspect of the images. I suppose that the conversion to PNG is not "one channel friendly". On my screen, the output is correct.

If you want the data in another format, just ask me.

image-natural.png - input (177.4 kB) Pierre Chatelier, 2012-06-21 03:17 pm

image-debayered-vng.png - wrong output with _VNG (391.4 kB) Pierre Chatelier, 2012-06-21 03:17 pm

image-debayered-normal.png - normal output with normal Debayer (304.3 kB) Pierre Chatelier, 2012-06-21 03:17 pm

color.cpp (140.7 kB) Kevin Smith, 2012-06-27 05:04 pm

Associated revisions

Revision 2759f026
Added by Ilya Lavrenov over 12 years ago

fixed Bug #2074

Revision 71914987
Added by Roman Donchenko about 11 years ago

Merge pull request #2074 from asmorkalov:android_nonfree_cuda

History

#1
Updated by Pierre Chatelier over 12 years ago

When I say "On my screen, the output is correct", I only talk about the general aspect of the images.
The bug to observe is the window, where much green appears in the VNG mode

#2
Updated by Andrey Kamaev over 12 years ago

  • Target version deleted (2.4.2)
  • Category set to imgproc, video

#3
Updated by Kevin Smith over 12 years ago

I have no idea how to submit patches but I ran into this bug while using the software and have a fix. All the code I am talking about is found here - http://code.opencv.org/svn/opencv/trunk/opencv/modules/imgproc/src/color.cpp The specific function is Bayer2RGB_VNG_8u This is happening because the variables x1, x2, and t1 sometimes have a sign bit in the MSB of the 16 bit values we are looking at. This way when we run the _mm_packus_epi16(x1, z), _mm_packus_epi16(x2, z), and _mm_packus_epi16(t1, z) lines of code it will pack down to zero instead of 255 like it is supposed to (thinks it is a negative number). I created a bug fix for my application that is working with the image attached as well as another image that I was testing with. I have attached my code fixes. Basically before packing I AND all the 16 bit values with 0x7fff so that it clears the sign bit and pack to 255 instead of zero.

  • File color.cpp added

#4
Updated by Gilad Kapelushnik over 12 years ago

I would also like to see this fixed. Thanks

#5
Updated by Vadim Pisarevsky over 12 years ago

  • Target version deleted ()

#6
Updated by Ilya Lavrenov over 12 years ago

thank you very much for the patch! the fix has been applied in 2759f0

  • Status changed from Open to Done
  • Assignee set to Ilya Lavrenov

#7
Updated by Andrey Kamaev about 12 years ago

  • Target version set to 2.4.3

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