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Rus Belikov
December 19, 2007, 23:45:56
Hi,

I recently got the DBK21AU04.AS with IC Capture.AS 2.0 and have a few questions:

1. What is the rms read noise in e-s?
2. What is the thermal background in e-s per s?
3. What is the well depth of each pixel in e-s?
4. How can I get the raw data from the camera's CCD? I turned off debayering, but how do I "turn off" gamma, brightness, gain, hue, saturation, white balance blue and white balance red? (It would be nice to get a formula relating the raw data and the final image that incorporates all these parameters.)
5. I assume the CCD is linear (i.e. constant gain where gain = pixel value/e-s). What is the value of this gain?
6. What is the difference between Y800 and BY8 (with "unspecified" codec), and when would I want to use one vs. the other? (Both support debayered and non-debayered images and are uncompressed.)
7. I assume the CCD has anti-blooming. At what pixel value does that kick in?
8. On the CCD pdf sheet (http://www.theimagingsource.com/products/cameras/sensors/icx098bq.pdf) on page 9, it says that there are two modes: progressive scan, which takes 1/30s to output all pixels with 400 TV-lines of resolution and a low quality "monitoring mode" that takes 1/60s to output pixels at 200 TV-lines of resolution. Does this mean that when operating in 60fps mode, I cannot get the full resolution of the CCD?

thank you!

Stefan Geissler
December 20, 2007, 10:13:31
Rus,

all available information can be seen at following link:
http://www.theimagingsource.com/en/products/cameras/usb_bayer/dbk21bu04/overview/
I am very sorry, but more information is not available.

Question 4:
Please use the Y800 video format. It provides the raw data.

The difference between Y800 and BY8 is only the name. The trick is that DirectShow will add automatically a color space transformation from raw data to RGB if the BY8 video format is in use. Thus you can colored images with the double frame rate than using UYVY video format.
If you want to perform the color calculation from the raw data on your own, you would use the Y800 video format.

The functionality of question 8 is not implemented in the camera. You will receive the VGA resolution of 640*480 pixels in all available frame rates, also 60 fps too.

I hope, this helps you a little bit. If not, please let me know.

Rus Belikov
December 21, 2007, 00:25:11
Thanks, Stefan.

Ragarding question 4, the Y800 format provides the "raw data" changed by the following parameters: {gamma, brightness, gain, hue, saturation, white balance blue, white balance red}, correct? Did I miss any parameters? That is actually not what I meant by "raw data". What I am interested in is getting pixel values that are proportional to the number of photons hitting the CCD (after the bayer filter, and not counting the bias, read and thermal noise). In other words, I would like pixel values that are proportional to the voltages output by the pixels, before any gammas or white balances are applied. So, to what should I set gamma and the white balance parameters (and the others if they are relevant) in order to achieve this?

Actually, all my questions would be answered by a formula showing exactly how IC Capture uses all these parameters.

By the way, are all these parameters applied before the 8-bit digitization or after? Are they applied on the camera or on the computer?

Regarding question 8, what do they mean on the CCD spec sheet (linked above) when they say that it takes 1/30s to read off all the pixels? Wouldn't that make it impossible to image at 60fps at full resolution?

Thanks again!

Stefan Geissler
December 21, 2007, 09:37:36
Rus,

If the cameras delivers raw data in Y800 or BY8 video format, then all color functions like white balance, saturation and hue are disabled. These functions are usable on YUV formats.
Gamma, brightness and gain are still active.
These parameters are applied in the camera, not in the computer.

I am afraid, then exact informations you asked for, are still not available from SONY, the CCD manufacturer.


Regarding question 8, what do they mean on the CCD spec sheet (linked above) when they say that it takes 1/30s to read off all the pixels? Wouldn't that make it impossible to image at 60fps at full resolution?
I guess you already tested this with your camera. And the images shows up completely 640x480 at 60 fps without loosing information.

Rus Belikov
December 21, 2007, 17:24:55
Thanks again for the quick reply! Imaging source support is some of the best I've seen! (And cameras as well of course.)

I noticed that for Y800/BY8 formats, even though the hue and saturation are disabled, the white balance is not (even when you turn off debayering).

So, what values should I use for white balance red and white balance blue to get an image that is the same as before white balance is applied? In other words, an image where the relative red/green/blue response is the same as given by the spectral transmission curves on the spec sheet? (By the way, are white balance red and blue applied on the camera as well?)

As for #8, so do you know what Sony means when they say it takes 1/30s to read off all the pixels given that it's possible to do it in 1/60s or less?

Stefan Geissler
December 21, 2007, 17:32:56
Thank you for the compliments.

These are the white balance values:


Register Value Red/Blue Amplification Green Amplification
0 -2 dB 4 dB
32 4 dB 4 dB
64 10 dB 4 dB
95 10 dB -2 dB

So a value of 32 for red and blue should be fine.

Question #8: No, I am not sure about this. I can only see, that the camera runs fine at 60 fps. Sorry for not having a better answer.

(I will be next wee out of office, so I want to wish merry Christmas and a happy new year. (Not only to you, but to all users!) )