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Subaru
May 6, 2008, 16:58:49
I use IC Capture and my DFK21AF04 to capture raw stream. I have chosen Y800 to record the AVI, but when I use Register4 to "Use Debayer" and GB to decode the stream, a checker pattern (light and dark) appears in the image.

The checker pattern is also apparent in the screen in the IC Capture.

I attached the issue image, and also the setting I used for the reference.

I expect after the debayer, the image should be smooth instead of having a checker pattern.

May anyone suggest how to fix this issue?

Subaru
May 6, 2008, 17:00:52
Here is the setting I use in Register4 to debayer the raw.

Stefan Geissler
May 7, 2008, 12:56:39
The checker pattern must be seen in the raw image, because the distribution of red, green and blue light in the daylight differs. But it should removed if the debayering has been done.

I magnified the first image but I was not able to find the checker pattern in it. There is only the noise visible. What was the exposure time? What about the Iris? I see, you used gain automatic, which can produce noise, if there is not enough light.

Subaru
May 7, 2008, 14:54:11
The checker pattern must be seen in the raw image, because the distribution of red, green and blue light in the daylight differs. But it should removed if the debayering has been done.

I magnified the first image but I was not able to find the checker pattern in it. There is only the noise visible. What was the exposure time? What about the Iris? I see, you used gain automatic, which can produce noise, if there is not enough light.
Thanks for your reply. The checker pattern I mentioned in the 1st image, is on the left, which is the blue sky besides the building. They are repeated pattern instead of the random noise. Since this is the daytime image, it should not be the random thermal noise, as the light is quite sufficient.

I also suspect it could be due to the debayer problem. I had tried BY8, but this pattern still exist.

I want to know how to debayer the image correctly to get rid of this checker pattern.

Stefan Geissler
May 7, 2008, 16:27:01
If an edge sensing debayer algorithm is use, then these patterns are created by the debayering.
The edge sensing is the default in IC Capture. I do not know, which is used by Registax.

Subaru
May 7, 2008, 17:27:51
If an edge sensing debayer algorithm is use, then these patterns are created by the debayering.
The edge sensing is the default in IC Capture. I do not know, which is used by Registax.
Is there any way to choose another algorithm in IC Capture if I choose BY8 to prevent this problem?

Stefan Geissler
May 8, 2008, 08:39:16
Yes. Please click on the "Device" menu, select "DeBayering" and then "Algorithm".

There is also an interesting program "AVIRaw", that implements seven different algorithms for testing. I am not shure, whether it can read the Y800 AVI files. Search in the www for this program.

Some more interesting links:

http://en.wikipedia.org/wiki/Demosaicing

and the best documentation about debayring:
http://scien.stanford.edu/class/psych221/projects/99/tingchen/main.htm