DFK Codec comparrison, Y800 & YUY2

[Space Cowboy]

Quite a few people seem to be having mixed results using the DFK/DBK21 618 cam. The main grievance is the bayer pattern that can appear after sharpening a stack when using the y800 or RAW codec.

Personally I find the y800 codec too noisy even without the bayer pattern. Here is a comparrison using identical capture and stacking/wavelet settings. The only difference between these 2 images is that one was taken using YUY2 video codec with RGB24 colour codec at 6-27am Sept 22nd. The other image taken at 6-31am using y800 video and y800 colour (RAW).

The RAW image clearly has more noise. Both images are from 3 min 30fps avis with 2000 frame stacks using 1.5x drizzle in AS!2. These are straight out of Registax wavelets no other processing has been performed,

YUY2

y800 (RAW)

[riklaunim]

Y800 raw would be non-debayered which then could be debayered with one of available algorithms. Grainy noise is related to camera read noise (and amplified by gain). If this noise is less visible with one of codecs then it's quite likely that it blurs the image slightly.

[KE400]

Thanks for posting about this topic Stuart, as you know, I am one of those folk who have been frustrated with the bayer pattern. I will certainly give the YUY2 video codec with RGB24 colour codec a go next time out.

Any other advice on capture setting using IC Cap would be greatly recieved.

Thanks again, a very good comparison

[neil phillips]

Y800 raw would be non-debayered which then could be debayered with one of available algorithms. Grainy noise is related to camera read noise (and amplified by gain). If this noise is less visible with one of codecs then it's quite likely that it blurs the image slightly.

would that be compression blurring do you think.. I didnt think compression blured. I thought compression created noise. As y800 has no compression. But yuy2 does. One would have expected things the other way around ?

[cgarry]

The YUY2 codec will be applying a noise filter after debayering. If you use the raw format codec then you get raw, unfiltered data. So these results are pretty much as I would expect them!

Cheers,

Chris

[neil phillips]

Just out of interest Stuart, to see what was underneath that noise i applied a frequency domain filter. which didnt intirely remove all the noise. so i then applied 5 filter size and 5 filter strength for the least amount possible to remove most of the remaining noise ( some does still remain )

But from what i can see. I think Rik is right. despite the horrible noise ( and it is bad ) even with quite drastic noise removal the image does appear a tad sharper to my eyes. See what you think. Personally because of the noise i would likely stick to yuy2. But i guess you figured that for yourself already.

Only frequency domain applied

Frequency domain plus adaptive noise reduction

[neil phillips]

The YUY2 codec will be applying a noise filter after debayering. If you use the raw format codec then you get raw, unfiltered data. So these results are pretty much as I would expect them!

Cheers,

Chris

Thats interesting Chris. That explains it perfectly. So in effect, might it be better to be applying our own filtering with such cameras

see my noise reduction on such said image

[cgarry]

Thats interesting Chris. That explains it perfectly. So in effect, might it be better to be applying our own filtering with such cameras

see my noise reduction on such said image

In theory you should be able to debayer and filter the raw frames to get exactly the same result. However, the built in filter will be tuned for the camera type so much of the work is done for you. I am not sure of the difference between applying a noise filter to all frames prior to stacking and applying a noise filter to a stacked image.

Personally, I do not like the though of using a codec that debayers the frame and then subsamples the colour again, you are never going to gain detail using that approach. On the other hand, if it works and is much easier then there is a lot going for this approach!

Cheers,

Chris

[neil phillips]

In theory you should be able to debayer and filter the raw frames to get exactly the same result. However, the built in filter will be tuned for the camera type so much of the work is done for you. I am not sure of the difference between applying a noise filter to all frames prior to stacking and applying a noise filter to a stacked image.

Personally, I do not like the though of using a codec that debayers the frame and then subsamples the colour again, you are never going to gain detail using that approach. On the other hand, if it works and is much easier then there is a lot going for this approach!

Cheers,

Chris

Agreed i think most will want a easier life

[cgarry]

A good way of looking into this is to look at dark videos with very high gamma and gain. It becomes obvious that noise filtering is being applied by the camera codec. At least it did when I did this some time back while looking into another problem.

[Space Cowboy]

Very interesting comments guys! I did not realise there was some compression with the YUY2 codec though that does make sense as when I've used y800 with RGB colour and activated the live de-bayer function the resulting avi file is larger.

Neil I tend to agree with Chris that the YUY2 noise filtering is probably more efficient than manual noise processing. It certainly would be easier on my hard drive space if I could make more use of the RAW avis though I do prefer to capture in colour as its easier to see whats going on with focus and seeing with a colour image.

[cgarry]

When I use my DFK I always do the focusing with a colour image. I have lost count of the number of times that I have forgotten to turn the debayering off and captured the debayed video in Y800 format. Doh!

Thinking about it Stuart, is it worth saving the final image in RGB24 format when it comes from the camera in YUY2 format? You could probably save a bit of hard drive space if you used YUY2 throughout.

Chris

[Space Cowboy]

I have lost count of the number of times that I have forgotten to turn the debayering off and captured the debayed video in Y800 format. Doh!

Yep I've done that a few time lol There is nothing that I hate more than ending up with a mono image.

Chris I've never tried YUY2 with YUY2 purely because I don't know enough about these codec combinations and when first having the DFK i saw folk used RG24 so I went that way. I shall give it a go!

[cgarry]

Using YUY2 with YUY2 should not lose you any more data so long at the capture program does not do anything silly like convert the incoming YUY2 stream to RGB and then back to YUY2. Stranger things have happened though.

[Space Cowboy]

Thanks Chris.

[PeterDen]

Hi, It looks everyone uses Y800 in here. Where do I get it?

..just trying to open an AVI file with MATLAB and it asks for Y800. Spent an hour and still can not find the download.

[gary1968]

Y800 is a setting in the IC software supplied with the camera. Its a while since I had my camera so can't remember exactly where it is. You have to set that prior to shooting the avi

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