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flyer
April 23, 2012, 00:01:12
I'd appreciate a few tips about capturing color properly with a DBK21AU618, a one shot color camera. I don't have these issues with Saturn, but Mars is very vexing. I'm using the Imaging Source software to capture, Y800, Debayering turned off....same as I do for Saturn, only getting very strange results.

The image on screen, pre capture, is completely red and featurless and looks blown out due to total red saturation. I pretty much have to reduce the red white balance slider to close to far left position to see any detail on the image, or have it look anything like what I kight expect Mars to look like through an eyepiece. In any case, I mess arond with the color controls, and gamma, gain, etc until I get an acceptable looking image on the screen (this, with Debayering "on"). Then I capture with Debayering off. The captured Debayered image is bright blue! Shouldn't it look like the screen image before turning Debayering off? Just prior to capture I alo check the histogram and it shows all three color channels putting out about equal values for RGB. That in itself seems odd because Mars is red, so wouldn't one expect the red channel to be stronger. I can increase red, but then the image on the screen is blown out and featurless. If I reduce gamma or gain I can start to see features but by that point the image is getting very dark and the captures lack enough intensity to process.

I'm capturing at 30fps (with a IR/UV filter) with my TEC140 at f35 and use the ROI set to around 240 x 240. When I Debayer after capture I am using AstroStakkert 2, or the Virtual Dub Debayering method, or FireCapture Debayering Tool....all give the same blue image. If I inspect the color channels in the resulting Debayered image using photoshop the red channel is very very reduced compared to the other two channels, but the blue channel looks blown out (that is way too intense). As I mentioned earlier the histogram in IS Cap shows about equal color intensity on all three channels with no clipping. For some reason I don't understand at all, the IS Software is showing a completely different image pre-capture.

Any tips much appreciated!

Stefan Geissler
April 23, 2012, 08:26:01
The only way to exchange red and blue channel is to use the wrong start pattern at debayering. The correct start pattern should be BG.

flyer
April 23, 2012, 13:57:41
Stefan, I'm quite positive that I am not interchanging these values because I can Debayer images of Saturn that have the correct colors, and because two of the software Debayering solutions that I mentioned, Autostakkert2 and VDub do not give one the option to set the Debayer pattern.

After searching this forum and others today I now suspect that the IR filter I have been using may not be "good" enough for the DBK21. Is this a possibility for what I am experiencing? For example, using the DBK21 without an IR filter, would one viewing Mars see a completely blown out image saturated in red? And, if consequently the red channel was reduced to nearly zero, and the image on screen then looked "ok," would the actual capture by the camera be overly balanced towards the blue/green channels after Debayering. My "blue" debayered images can be made to display normal expected color in photoshop by adjusting the histogram levels in each channel.

Here is an example (a very poor out of focus image but my point is the color issue):

flyer
April 23, 2012, 14:00:38
Final image after histogram level adjustments. After adjusting levels the image is starting to look like the pre-capture image, except there is no indication of the blown out area on the rights side of the image. I just cannot understand why the pre-capture looks "ok," and the initial Debayered image looks blue!

1483

Stefan Geissler
April 23, 2012, 15:11:14
Hello

The IR Cut filter removes the IR color only, beginning at ~670 nm. The normal daylight, 370 - 750 nm should get through the filter, therefore, you should get enough red. What have been the white balance settings?

I also can not understand, why the images look different, except the debayering of the raw data is different from our debayering.

I suppose "blown out" means "over exposed"?

Stefan Geissler
April 23, 2012, 15:42:46
Since I had a second thread somewhere with Mars photographing, I searched a little bit in the internet for "DBK 618 mars camera settings". I found nothing in particular, but there are many astronomy forums showing images of Mars done with this camera. You may search on your own too and take part in the discussions. I think, you can get better help from astronomers, than from me, because I am in machine vision, not astronomy.

asimov
April 23, 2012, 17:05:21
I use both DBK camera's (old chipped version & now the 618) & there is no issue in this respect. Naturally you should not rely on any auto functions & manually set your white balances in R & B.

1486

flyer
April 23, 2012, 23:20:49
Stefan,

I appreciate your reply, and I have no doubt seen fine images of Mars taken with this camera! However, your comment "I also can not understand, why the images look different, except the debayering of the raw data is different from our debayering." is curious given that IS offers no IS method to Debayer data post capture. We are forced to rely on 3rd party software. Given that I can properly Debayer data of Saturn is proof enough in my mind that my problem is not with Debayering.

I continue to suspect that the IR filter may be the issue and I will report back after I have a chance to test further. In the meantime here is a view of the capture settings I need to set on my screen (pre-capture) for Mars to show a normal amount of red and some detail on the surface.

1487

asimov
April 24, 2012, 07:16:29
Stefan,

I appreciate your reply, and I have no doubt seen fine images of Mars taken with this camera! However, your comment "I also can not understand, why the images look different, except the debayering of the raw data is different from our debayering." is curious given that IS offers no IS method to Debayer data post capture. We are forced to rely on 3rd party software. Given that I can properly Debayer data of Saturn is proof enough in my mind that my problem is not with Debayering.

I continue to suspect that the IR filter may be the issue and I will report back after I have a chance to test further. In the meantime here is a view of the capture settings I need to set on my screen (pre-capture) for Mars to show a normal amount of red and some detail on the surface.

1487




Hi Flyer. You should really have your brightness slider set to zero. I note your hue slider is out also. That should be exactly at the half way point. This will effect your balance greatly.

Stefan Geissler
April 24, 2012, 08:27:44
is curious given that IS offers no IS method to Debayer data post capture. We are forced to rely on 3rd party software.

This is simple: We are in machine vision. Astronomers detected the cameras some years ago and found them suitable for their needs. We are no astronomers, therefore, we can not write suitable software for astronomy needs. Third party programs like Registax, MaximDL needed years of development to get their todays standard. We can not make the same as fast.

For your camera settings: Asimov gave some very good hints.

flyer
April 24, 2012, 15:01:29
Thank you for your answers! I have to admit that I am feeling more than a little embarassed tonight after more experimenting.

Firstly I tried a different IR filter and noticed immediately that I had considerably more range within the red balance control. I was not able to adjust the hue control at all. The slider would move, but there appeared no effect visually or in the histogram. I turned on "auto white balance" and then I could adjust the hue control. After I turned off Auto White I could still adjust the hue control so that is a confusing result.

It turns out that my Debayering attemps were at fault after all and the red and blue channels were being swapped. The AutoStakkert2 program has a setting to automatically detect the correct Debayering setting and that aspect of the program is not functioning properly (it seems). When I figured out how to "force" BGGR everything became normal. I wasn't having this problem with ROI captures that are larger than my Mars captures so perhaps there is something different about the way the avi file looks to the Debayering programs I know about. I will do more experimenting with this. I feel kind of stupid getting something this elementary wrong and leading you on a wild goose chase! Sorry!!!

I don't want to e argumentative, but I actually don't quite understand your comments about the lack of Debayring IS might offer users of your camera. I know for many users that the whole Debayering process is confusing initially, and now I've made it all too clear that even longer time users of your cameras can mess things up pretty easily. Here is what I don't get: During capture it is possible to turn Debayering on in IS software, and even choose the type of Debayering (such a bilinear etc) and view an image in color. Why is it not possible to play back the recorded Y800 video and access Debayering by software that share the same features that seem already built into the software? I'm not suggesting that you provide "astronomy software" that does anything like Registax or MaxIm, etc.....just a simple program "tool" that accepts Y800 video and outputs a new avi file that is RGB. I don't know if you have looked at the Debayer tool in FireCapture. It would be a perfect tool accept that it isn't particularly fond of IS avi files for some reason. A tool like that made for IS cameras would simplify life for a lot of adopters of your cameras. Thanks for considering what I've written. And, again sorry for my mistakes in solving this problem!!

Peter
PS Let me kow if you want me to send you a copy of that Debayering Tool....

flyer
April 24, 2012, 15:02:31
Thank you for your answers! I have to admit that I am feeling more than a little embarassed tonight after more experimenting.

Firstly I tried a different IR filter and noticed immediately that I had considerably more range within the red balance control. I was not able to adjust the hue control at all. The slider would move, but there appeared no effect visually or in the histogram. I turned on "auto white balance" and then I could adjust the hue control. After I turned off Auto White I could still adjust the hue control so that is a confusing result.

It turns out that my Debayering attemps were at fault after all and the red and blue channels were being swapped. The AutoStakkert2 program has a setting to automatically detect the correct Debayering setting and that aspect of the program is not functioning properly (it seems). When I figured out how to "force" BGGR everything became normal. I wasn't having this problem with ROI captures that are larger than my Mars captures so perhaps there is something different about the way the avi file looks to the Debayering programs I know about. I will do more experimenting with this. I feel kind of stupid getting something this elementary wrong and leading you on a wild goose chase! Sorry!!!

I don't want to e argumentative, but I actually don't quite understand your comments about the lack of Debayring IS might offer users of your camera. I know for many users that the whole Debayering process is confusing initially, and now I've made it all too clear that even longer time users of your cameras can mess things up pretty easily. Here is what I don't get: During capture it is possible to turn Debayering on in IS software, and even choose the type of Debayering (such a bilinear etc) and view an image in color. Why is it not possible to play back the recorded Y800 video and access Debayering by software that share the same features that seem already built into the software? I'm not suggesting that you provide "astronomy software" that does anything like Registax or MaxIm, etc.....just a simple program "tool" that accepts Y800 video and outputs a new avi file that is RGB. I don't know if you have looked at the Debayer tool in FireCapture. It would be a perfect tool accept that it isn't particularly fond of IS avi files for some reason. A tool like that made for IS cameras would simplify life for a lot of adopters of your cameras. Thanks for considering what I've written. And, again sorry for my mistakes in solving this problem!!

Peter
PS Let me kow if you want me to send you a copy of that Debayering Tool....

Stefan Geissler
April 24, 2012, 16:33:02
Hello,

I will think about a converting tool, but I can not say, whether I will do this.

Stefan Geissler
April 24, 2012, 16:33:28
Hello,

I will think about a converting tool, but I can not say, whether I will do this.

Stefan Geissler
April 25, 2012, 08:12:43
Dear Flyer,

you already have the tool. Simply choose a color format, e.g. BY8 for the camera and RGB24 as "codec" for AVI capture in IC Capture.