4:4:4 10bit single CMOS HD project

Steve Nordhauser · June 9th, 2004, 06:36 AM

There are a couple of different gain settings to think about. The signal that comes from the pixel site is an analog level. In the Micron chip, there are 4 analog gain amplifiers (R, G1, G2, B) that are multiplexed to match the Bayer pattern. These must be correctly adjusted to get the full swing of analog input voltage to the A/D. Otherwise, you lose dynamic range. The voltage may only go 0- 0.5V when the full scale on the A/D (10 bit range) is 0-1V. XCAP then provide all the digital gain, gamma and stretching tools, but if you stretch too low a signal, you get some stepping in the shading. The only gain you need to worry about in capture is this analog gain (and exposure of course to get the swing).

XCAP can histogram the data across a line you place in the viewing window. I use this when I am adjusting gain and exposure since you can see when you are clipping. I think anyone who does some programming should play with the XCAP tools a bit. There are quite a few clever ones. My favorite is the extraction of a color transformation table (color balance) from an image of a Macbeth target.

Rob Scott · June 9th, 2004, 06:42 AM

<<<-- Originally posted by Obin Olson : I could just remove the k3 lens and have a little c-mount sticking out the front..-->>>

Obin, have you thought about buying a C-mount adapter -- like this one for a Nikon mount -- and then using 35mm SLR lenses?
http://www.bhphotovideo.com/bnh/cont...=116733&is=REG

Steve Nordhauser · June 9th, 2004, 06:51 AM

Rob,
If you don't need wide angle, this is the cheapest route to great optics. I use my Canon FD lenses and some T mount telephotos all the time. The down sides are that they are slow in all but 50mm compared to c mount (try to get a 25mm f1.4 Nikon) and the field of view is narrower because the sensor dimensions are smaller than a 35mm negative.

But, great glass and almost free. The adapter is cheap and you can get used manual lenses all over ebay.

Obin Olson · June 9th, 2004, 06:52 AM

good idea Steve, tell Rob and Rob about the tools in xcap. Jason, if all you could get from this camera was 8bit I don't think it would be that great. Because of 10bit we can push the image around pretty much in Post...I chose this camera on 3 things, price, image quality and bit depth...As far as I know this is the best "bang-for-the-buck" going at this moment.. One of the big things I don't like is it's not 2/3rd inch chip so now the FOV will be very narrow with the 16mm cinema lenses, to deal with this I may re-think my idea and use c-mount lenses somehow in the 16mm camera body.

today i think I will shoot some side-by side tests with the dvx100 and see just what the dynamic range is when you compare it to a professional camera that is made for tv production...maybe even shoot some with our JVC 500 that has 1/2inch chips

it's the FOV I am worried about, I need to shoot wide alot...ideas for this Steve with a 35mm lens?

Rob Scott · June 9th, 2004, 07:07 AM

<<<-- Originally posted by Obin Olson : it's the FOV I am worried about, I need to shoot wide alot... -->>>

Right ... the only solution I can think of would be a ground glass adapter.

... or perhaps an optical reducer of some sort. I think I remember reading about it on one of the GG threads. You don't get the 35mm DOF, but it does focus the image so you get a better FOV on your smaller chip. And presumably it wouldn't lose as much light either.

Obin Olson · June 9th, 2004, 07:14 AM

i think that is what I want an optical reducer.. links to get one Steve?

I will also try and shoot with the gg adaptor today and see how bad the grain is fron the spinning GG

hmmm I found a 4.5mm wideangle c-mount canon lens on ebay...wonder if that would give me a nice wide-angle shot with the 1300 camera

Richard Mellor · June 9th, 2004, 09:31 AM

found a link for $799 camera link card

http://www.opsci.com/index.asp?paget...arch&exten=asp

Steve Nordhauser · June 9th, 2004, 09:38 AM

First, on relay lenses, this looks interesting:
http://www.edmundoptics.com/onlineca...productid=1491

I would suggest someone call edmund for some technical help as see if they do what I think they do - increase/decrease the image size in a fairly short space as an option over ground glass. Image quality and light loss are the two concerns.

Next, Obin, if the lens is at least 1/2" optical format, you will get an image. For a 5 micron pixel all but cheap lenses will be OK. A bit better corner focus with the better lenses.

Last, Richard, we sell the bundle with a 32 bit Epix frame grabber, 2m camera link cable, power supply and cable and XCAP-lite for $500 more than the camera cost. We will have a 64 bit bundle fairly soon, also pretty cheap ( a word that carries much relative meaning - I've bought used cars for less than this).

Jason Rodriguez · June 9th, 2004, 09:55 AM

Hey Steve,

Using XCAP, what is the process that one must go through to go from camera to a useable image sequence, such as 16-bit TIFF? I mean what is XCAP saving to, how is it saving it, if it's not a useable image, what must be done with the "files" it saves in order to make them useable? Is it saving one big binary file, or are there individual file sequences that can be saved for each frame? Do you have to turn the computer on before the camera, "opening/closing" the board, etc., I guess in all this discussion I'm getting a bit confused in what must actually be done in order to get useable RGB images that can then be further processed. Knowledge of what it actually takes would greatly help in trying to sort out this process.

BTW, can XCAP or at least its functions be run from a command prompt in windows?

Richard Mellor · June 9th, 2004, 10:05 AM

that sounds great steve

thanks again for all your help . I hope that you can hang in here with all of us starving artists

Obin Olson · June 9th, 2004, 10:24 AM

I held up our 16mm lens to a sheet of paper and held up the c-mount..looks like they are the same size indeed! this is good

dvx100 upsized to 1280 hd...

http://www.dv3productions.com/test_i...x100at1280.jpg

Jason Rodriguez · June 9th, 2004, 10:58 AM

Hey Obin,

Just curious, but that DVX100 shot looks pretty bad. Noisy and overexposed. Could it have been exposed better, or was the background pretty dark and you had to lift the levels to compensate?

I guess I'm having a hard time really evaluating these setups because I have no idea how much range is in these images. What one camera sees is not what another is seeing. You wouldn't happen to have access to a light meter, would you? If so, what stop is your key at, and what stop is the background at? How many stops over are your highlights, and how many stops under are the shadows? What is the maximum range in these scenes? I mean if your highlights are five-six stops over the key, then of course it doesn't matter what you shoot, you're going to clip, even on film. Are we clipping after three stops over? If so that's not so good, unless you can, like the D60/10D, underexpose by up to 2 stops and not even notice the difference in most cases (which would bring you back to five stops over) relative to your noise levels. I hope you don't feel like I'm frustrating your efforts, but It's really hard to visualize just what you're getting if there's no standard. Again, that DVX100 shot looks bad (nasty clipped highlights), I've seen the DVX look much better (I used to own one before selling it). So again, if you have a light meter, or access to a grey card/macbeth chart, and could shoot the cards at normal exposure, 3 or 4 stops over and 3 or 4 stops under, that would help us understand just what the dynamic range of this camera really is. I know this sounds like a lot, and I do want you to know that I'm really excited about your frame grabs that you've been showing here, I'm just trying to understand where they fit in the scheme of things in comparsion to other broadcast cameras I know.

Steve Nordhauser · June 9th, 2004, 11:15 AM

Jason,
You can download XCAP here:
ftp://ftp.epixinc.com/downloads/xcapwi.exe
If you do the install, you will get the full docs in html format. It is meant as a GUI.

You save to a big binary file. Then you do a file save as into other formats with lots of options. If you want to do the Bayer externally, tell it the camera is monochrome.

Jason Rodriguez · June 9th, 2004, 11:32 AM

So XCAP can do bayer conversion internally?

Obin Olson · June 9th, 2004, 12:44 PM

Jason I will try and go to JDC here in town I am sure they have the charts

guys I got some 24p 1280x720 footage today!!!!! I did not have enough time to post online but I will do it when I go to work in the morning...stuff looks VERY good and it's only 8bit! gota upgrade disk drives for 10bit

June 9th, 2004, 06:36 AM	#121
Steve Nordhauser Silicon Imaging, Inc. Join Date: May 2004 Location: Troy, NY USA Posts: 325	There are a couple of different gain settings to think about. The signal that comes from the pixel site is an analog level. In the Micron chip, there are 4 analog gain amplifiers (R, G1, G2, B) that are multiplexed to match the Bayer pattern. These must be correctly adjusted to get the full swing of analog input voltage to the A/D. Otherwise, you lose dynamic range. The voltage may only go 0- 0.5V when the full scale on the A/D (10 bit range) is 0-1V. XCAP then provide all the digital gain, gamma and stretching tools, but if you stretch too low a signal, you get some stepping in the shading. The only gain you need to worry about in capture is this analog gain (and exposure of course to get the swing). XCAP can histogram the data across a line you place in the viewing window. I use this when I am adjusting gain and exposure since you can see when you are clipping. I think anyone who does some programming should play with the XCAP tools a bit. There are quite a few clever ones. My favorite is the extraction of a color transformation table (color balance) from an image of a Macbeth target. __________________ Silicon Imaging, Inc. We see the Light! http://www.siliconimaging.com

June 9th, 2004, 06:51 AM	#123
Steve Nordhauser Silicon Imaging, Inc. Join Date: May 2004 Location: Troy, NY USA Posts: 325	Rob, If you don't need wide angle, this is the cheapest route to great optics. I use my Canon FD lenses and some T mount telephotos all the time. The down sides are that they are slow in all but 50mm compared to c mount (try to get a 25mm f1.4 Nikon) and the field of view is narrower because the sensor dimensions are smaller than a 35mm negative. But, great glass and almost free. The adapter is cheap and you can get used manual lenses all over ebay. __________________ Silicon Imaging, Inc. We see the Light! http://www.siliconimaging.com

June 9th, 2004, 09:31 AM	#127
Richard Mellor Major Player Join Date: Nov 2003 Location: cambridge ma Posts: 247	camera link found a link for $799 camera link card http://www.opsci.com/index.asp?paget...arch&exten=asp

June 9th, 2004, 09:38 AM	#128
Steve Nordhauser Silicon Imaging, Inc. Join Date: May 2004 Location: Troy, NY USA Posts: 325	First, on relay lenses, this looks interesting: http://www.edmundoptics.com/onlineca...productid=1491 I would suggest someone call edmund for some technical help as see if they do what I think they do - increase/decrease the image size in a fairly short space as an option over ground glass. Image quality and light loss are the two concerns. Next, Obin, if the lens is at least 1/2" optical format, you will get an image. For a 5 micron pixel all but cheap lenses will be OK. A bit better corner focus with the better lenses. Last, Richard, we sell the bundle with a 32 bit Epix frame grabber, 2m camera link cable, power supply and cable and XCAP-lite for $500 more than the camera cost. We will have a 64 bit bundle fairly soon, also pretty cheap ( a word that carries much relative meaning - I've bought used cars for less than this). __________________ Silicon Imaging, Inc. We see the Light! http://www.siliconimaging.com

June 9th, 2004, 10:05 AM	#130
Richard Mellor Major Player Join Date: Nov 2003 Location: cambridge ma Posts: 247	camrea link that sounds great steve thanks again for all your help . I hope that you can hang in here with all of us starving artists

June 9th, 2004, 06:42 AM	#122
Rob Scott Major Player Join Date: May 2004 Location: Knoxville, TN (USA) Posts: 358	<<<-- Originally posted by Obin Olson : I could just remove the k3 lens and have a little c-mount sticking out the front..-->>> Obin, have you thought about buying a C-mount adapter -- like this one for a Nikon mount -- and then using 35mm SLR lenses? http://www.bhphotovideo.com/bnh/cont...=116733&is=REG

June 9th, 2004, 06:52 AM	#124
Obin Olson Trustee Join Date: Jan 2003 Location: Wilmington NC Posts: 1,414	good idea Steve, tell Rob and Rob about the tools in xcap. Jason, if all you could get from this camera was 8bit I don't think it would be that great. Because of 10bit we can push the image around pretty much in Post...I chose this camera on 3 things, price, image quality and bit depth...As far as I know this is the best "bang-for-the-buck" going at this moment.. One of the big things I don't like is it's not 2/3rd inch chip so now the FOV will be very narrow with the 16mm cinema lenses, to deal with this I may re-think my idea and use c-mount lenses somehow in the 16mm camera body. today i think I will shoot some side-by side tests with the dvx100 and see just what the dynamic range is when you compare it to a professional camera that is made for tv production...maybe even shoot some with our JVC 500 that has 1/2inch chips it's the FOV I am worried about, I need to shoot wide alot...ideas for this Steve with a 35mm lens?

June 9th, 2004, 07:07 AM	#125
Rob Scott Major Player Join Date: May 2004 Location: Knoxville, TN (USA) Posts: 358	<<<-- Originally posted by Obin Olson : it's the FOV I am worried about, I need to shoot wide alot... -->>> Right ... the only solution I can think of would be a ground glass adapter. ... or perhaps an optical reducer of some sort. I think I remember reading about it on one of the GG threads. You don't get the 35mm DOF, but it does focus the image so you get a better FOV on your smaller chip. And presumably it wouldn't lose as much light either.

June 9th, 2004, 07:14 AM	#126
Obin Olson Trustee Join Date: Jan 2003 Location: Wilmington NC Posts: 1,414	i think that is what I want an optical reducer.. links to get one Steve? I will also try and shoot with the gg adaptor today and see how bad the grain is fron the spinning GG hmmm I found a 4.5mm wideangle c-mount canon lens on ebay...wonder if that would give me a nice wide-angle shot with the 1300 camera

June 9th, 2004, 09:55 AM	#129
Jason Rodriguez Trustee Join Date: Mar 2003 Location: Virginia Beach, VA Posts: 1,095	Hey Steve, Using XCAP, what is the process that one must go through to go from camera to a useable image sequence, such as 16-bit TIFF? I mean what is XCAP saving to, how is it saving it, if it's not a useable image, what must be done with the "files" it saves in order to make them useable? Is it saving one big binary file, or are there individual file sequences that can be saved for each frame? Do you have to turn the computer on before the camera, "opening/closing" the board, etc., I guess in all this discussion I'm getting a bit confused in what must actually be done in order to get useable RGB images that can then be further processed. Knowledge of what it actually takes would greatly help in trying to sort out this process. BTW, can XCAP or at least its functions be run from a command prompt in windows?

June 9th, 2004, 10:24 AM	#131
Obin Olson Trustee Join Date: Jan 2003 Location: Wilmington NC Posts: 1,414	I held up our 16mm lens to a sheet of paper and held up the c-mount..looks like they are the same size indeed! this is good dvx100 upsized to 1280 hd... http://www.dv3productions.com/test_i...x100at1280.jpg

June 9th, 2004, 10:58 AM	#132
Jason Rodriguez Trustee Join Date: Mar 2003 Location: Virginia Beach, VA Posts: 1,095	Hey Obin, Just curious, but that DVX100 shot looks pretty bad. Noisy and overexposed. Could it have been exposed better, or was the background pretty dark and you had to lift the levels to compensate? I guess I'm having a hard time really evaluating these setups because I have no idea how much range is in these images. What one camera sees is not what another is seeing. You wouldn't happen to have access to a light meter, would you? If so, what stop is your key at, and what stop is the background at? How many stops over are your highlights, and how many stops under are the shadows? What is the maximum range in these scenes? I mean if your highlights are five-six stops over the key, then of course it doesn't matter what you shoot, you're going to clip, even on film. Are we clipping after three stops over? If so that's not so good, unless you can, like the D60/10D, underexpose by up to 2 stops and not even notice the difference in most cases (which would bring you back to five stops over) relative to your noise levels. I hope you don't feel like I'm frustrating your efforts, but It's really hard to visualize just what you're getting if there's no standard. Again, that DVX100 shot looks bad (nasty clipped highlights), I've seen the DVX look much better (I used to own one before selling it). So again, if you have a light meter, or access to a grey card/macbeth chart, and could shoot the cards at normal exposure, 3 or 4 stops over and 3 or 4 stops under, that would help us understand just what the dynamic range of this camera really is. I know this sounds like a lot, and I do want you to know that I'm really excited about your frame grabs that you've been showing here, I'm just trying to understand where they fit in the scheme of things in comparsion to other broadcast cameras I know.

June 9th, 2004, 11:15 AM	#133
Steve Nordhauser Silicon Imaging, Inc. Join Date: May 2004 Location: Troy, NY USA Posts: 325	XCAP Jason, You can download XCAP here: ftp://ftp.epixinc.com/downloads/xcapwi.exe If you do the install, you will get the full docs in html format. It is meant as a GUI. You save to a big binary file. Then you do a file save as into other formats with lots of options. If you want to do the Bayer externally, tell it the camera is monochrome. __________________ Silicon Imaging, Inc. We see the Light! http://www.siliconimaging.com

June 9th, 2004, 11:32 AM	#134
Jason Rodriguez Trustee Join Date: Mar 2003 Location: Virginia Beach, VA Posts: 1,095	So XCAP can do bayer conversion internally?

June 9th, 2004, 12:44 PM	#135
Obin Olson Trustee Join Date: Jan 2003 Location: Wilmington NC Posts: 1,414	Jason I will try and go to JDC here in town I am sure they have the charts guys I got some 24p 1280x720 footage today!!!!! I did not have enough time to post online but I will do it when I go to work in the morning...stuff looks VERY good and it's only 8bit! gota upgrade disk drives for 10bit