@Jason:
To me It looks the original image is a little too high......

@Steve:

What do you talk about when you talk about "low sensitivity"??

About the FPN, is it always the same?
Can I remove it ,I'm really interested about that chip.
Having 12 bits and 2048 would be great for my work so I want to know everything.
Besides it supports 48 fps in 1920x1080.....

Juan I bet your right...you REALLY have to expose for the highlights on this chip in the RAW format

so??
Is it overexposed??
I think we're going the right way now with all this new discoverings and tests...I'm so happy :)

What about the streaks in the shadows?
Did you read my post above?

BTW, My friend DP, tested yesterday the relay lens conbined with a lens for a 6x4 camera.
Amazing!!! he gained almost 1 1/2 f-stops against his SRL lens..

The problem is he was using a single un-coated lens, so image quality wasn't good.
Now we're heading to an optics factory to ask for help...

Dooh! I thought you were in Europe :).

Still this log trick that Sumix is doing for Bens camera, would it make sense for SI to do it for your camera too?

Hey there,

Fascinating work everyone. I'm currently trying to get through all of the posts. I can only do this at work at the mo' so I'm only up to page 51. There's a lot of reading to get done. My interest here is mostly as a geek. Not sure what if anything I can contribute but I just thought I'd share something before I asked any stupid questions.

I read on part of the thread that someone had looked at the possibility of adapting virtualdub to work with the files but it only worked with 8bit. I was wondering if that person had also looked into Avisynth. Avisynth is a frameserver, which virtualdub has, but has the advantage of being much faster and scriptable. Unfortunately, i can't find any info about the colour depth it handles.

Why, you might ask. If it could be engineered to work with the files, you would be able to keep the original format and create a 'virtual avi' which is basically a dummy file that redirects the individual frames through avisynth and into your app. The app thinks that the dummy file is a standard avi. No compression artifacts, hopefully no loss of information and hopefully more compatability. You could ideally create scripts which would allow you to open the files in nearly everything (eg dropping from 10 to 8 bit to work in premiere)

Just a thought.

Jason :)

Forget about it!! :)
Avisynth is heavily assembler optimized, has a lot of memory leaks, eats a lot of memory.
It looks faster to you because it works most of the time directly in YV12 colorspace.
When you use it in RGB, the same colorspace Vdub uses, it isn't faster.
Also it is very windows based so it is almost imposible to port it to any other OS.
Any of the things you are proposing would take more than 6 months of heavy work and a complete re-writing from scratch even if its developers (Shodan and Company) were working on it.

A Lite Light Revolution!
 

<<<-- Originally posted by Juan M. M. Fiebelkorn :BTW, My friend DP, tested yesterday the relay lens conbined with a lens for a 6x4 camera.
Amazing!!! he gained almost 1 1/2 f-stops against his SRL lens.. -->>>

This is what I'm talking about Obin. Stuff it, I'll reveal some of my plans, I wanted to keep them quiet so I could rub it in the noses of those people on my thread last year, but this is it. I was planning on using a Medium Fomat prime for indoor shoots, and a slr zoom (adjusted for MF for outdoor shoots). I was even eyeing a 30cm+ large format for night shooting (by moonlight, Starlight would be better, but I think that would require a truck to carry it ;). I suppose my doco's wont look so good if somebody else beats me to it, but I am getting tired of keeping it quiet. I've come up with many good computer inovations in the past, only to slowly see them erroded away as others, eventually, develope and exploit the same ideas (not saying that plenty of people haven't allready thought of condensing larger formats down to do low light, it is such a no brainer). But optically I think I still have got a few cards left.

Juan, are you talking about 6 by 4 inches, is he using a GG, because he should be getting more stops than that. Does the lense have a small aperture. I did some rough calculations previously and the best aperture lense for MF should give much more light (condensed) than a f1.0 SLR.

Ok, another stupid suggestion. Is there anything in Cinepaint AKA FilmGimp that might be useful?

Also, even if Avisynth is not practical, is some sort of frameserver style of app worth looking at so you can work using the original without having to duplicate your footage to work with it in your NLE?

Jason :)

18% grey card
 

How exactly would an 18% grey card help define exposure with this cmos camera?
With film, defining a single point along the response curve of film works, because the film toe, shoulder and whole response curve has been defined by the film manufacturer. With the Cmos camera, you can control the gain and offset of the chip, so you need more definition of a curve to nail down the 'exposure'.

I recommend shooting the equivalent of a sensotometric strip to help calibrate the camera. If you wanted to, you could even mimic the response curve of a particular film stock. I have a bit of color management experience under my belt from my last 'regular' job.

But it's also possible to just match it up visually to something on the monitor, without doing all the science.

Just a couple of things to think about.

-Les

hey obin,
did you ever figure out how to get rid of the bending of the image that happens with fast pans? i remember, from the footage you posted awhile ago, the bottom of the image would have to catch up to the top, and smear... was that solved by shutter or mhz or something?

Wayne on 1920HD:
That artsy shot was my boss shooting his wife. We are having troubles with Altasens getting more parts, especially color ones. This may push back a formal release date but I am trying to get more engineering parts for the developers - hardware and software

Juan on 3170 sensitivity:
Two separate issues. First, at a gain of 1, you need a brightly lit conference room type lighting (yeah, I know that is not too numerical) to get a good image. Second, as you increase the gain beyond about 3x, the FPN becomes obnoxious. Sure you can background subtract a reference and it doesn't look too bad, but you lose dynamic range doing that. You can clean things up. Look at this (with a poor Bayer, I know):
http://host196.ipowerweb.com/~silico...%208%20bit.jpg
http://host196.ipowerweb.com/~silico...h%20Photo2.jpg
I want to stress that these are well lit, gain and offset corrected, color tweaked, *NOT* raw.

Obin:
I'm glad you are making headway on the SI-1300 smear. Are you shooting at 24 or 48fps?

Ben:
I'm not sure if I see the advantage of the IBIS-5 in rolling shutter mode - larger pixels and cheap interface I guess. The main interest was in using the global shutter to remove the rolling shutter artifacts.

On log encoding:
There are two ways I can think of doing this - first with a log amplifier before the A/D. This will give you more dynamic range a the expense of less detail at one end of the brightness. I assume (??) that you want more detail i the shadows, not less so you get more steps in the dark areas. We just opted to use an external 12 bitA/D instead of the internal 10 bit to accomplish this on our IBIS-5 camera.

The second way would be to remap the 10 bit data down to 8 bit non-linearly to maintain the 10 bit dynamic range and detail at one end of the illumination, again at the expense of the rest of the range.

Personally, I would see more value in either straight 12 bits or going to a lossless compression if data rate is the issue (as in USB). Maybe I'm missing something here.

That BBC HD work is great, I'm watching the "Chicargo" musical stage show scene in AB Fab at the moment.

Steve, I'll leave this to the professionals, but I'm sure there is more. I think it is a matter of how our eyes work (non linear response curve with value to value at different distances (the eyes uses around 128 green values etc, 256 is used because that are not even), so if you can select the values according to the eyes performance curve, you can get the 10bit values to go a lot further. I have a link to the spectacular JVC GY-DV5000 camera, that I was reading last night, it uses a simular technique. I think if it is done right, then you adjust for the highlights and most of the picture range will be right, with crushed blacks (but I don't know how this goes in post editing).

http://www.provis.com.au/products/video/gy_dv5000.htm

Can somebody verify if I'm saying the right thing or not?

Quote from the link above:
400% of what?


Now that is performance, even at 1/2inch, but how does that compare to the Altsens?

I think, I read of a manufacturing problem with the Altsens constricting supply here, pity.

Thanks

Wayne.

It's a homebuilt, using an ASUS motherboard. Unfortunately, ASUS does not have a "ship replacement first" option -- I have to ship the motherboard in, they fix/replace, then ship it back. Grrr.Very possibly. The plan right now is to make the "Convert" software (the offline, non-real-time portion) available under the GPL, which means we could incorporate code from projects like Cinepaint.

Also, we plan to support file formats that Cinepaint can use directly -- meaning, you could use Cinepaint for color correction, gamma correction, etc. (Assuming that it supports those features -- haven't used it much myself.)

The idea behind Log encoding is that the human response to light is logarithmic, meaning we see more differentiation at the bottom of the scale (darks), than in the highlights. So loss of information in the highlights isn't a problem, and you're packing the bits more effectively. Also log encoding has a nice curve into the highlights, compressing them nicely rather than the harsh clip that happens with linear encoders when they hit 100%. So when you convert from log to linear, you can define a "soft-clip" that allows the highlights to gently roll off-log encoding according to the Cineon spec allows for super-whites, placing 90% white at 695 (I think), and then devoting the rest of the scale above that point to the 1024 cut-off to super-whites. This added information in the highlights helps to make a nice print, since again, there's information in the highlights that makes it to the film negative without any harsh clipping.

>>so??
Is it overexposed??
I think we're going the right way now with all this new discoverings and tests...I'm so happy :)<<

Actually I think the image is underexposed.... I was looking at it with the histogram and the blacks are seriously compressed/clipped. I checked out all the other images as well - same problem.

Why is it so necessary to expose for the highlights? Is it not possible to get good blacks without blowing out the image? I admit I'm somewhat lost...

the problem with the 1300 is yes its got good dynamic range but you can't use it when you have a hotspot in your image...you have to crush the blacks enough to "hide" the smear doing so cuts down the range alot...if your not shooting with a hotspot it works GREAT

These images are un-gamma corrected linear images, so yes, they actually are overexposed a little bit (although the last couple that Obin posted with the girl are pretty good, still might be bright, but not like the others from before).

Les Dit,

I was thinking that Steve might know the ISO.

Another thing you could do is check to see what F-stop gives a grey card lit with 2000lux a 50% grey value (after gamma correction) on screen. From there you could back-track to an ISO figure.

@JasonKeenan: Is there anything in Cinepaint AKA FilmGimp that might be useful?

No. Cinepaint is a frame-by-frame retouching tool, not an editing tool. It's literally mostly used for "dustbusting," or painting dust out of film scans. It's also an extremely early beta (I would call it an alpha), so while certain features like the "open" menu item and the "brush" tool are usable because they're the main features, pretty much everything else is some form of broken.

But I lurk on the Cinepaint developer list to get an idea what they're doing. 0.19 should be released fairly soon.


@Steve: I'm not sure if I see the advantage of the IBIS-5 in rolling shutter mode - larger pixels and cheap interface I guess.

Yeah, not much of an advantage, I guess. No wait, it is!

I could never shoot with a 1/2" sensor, because you can't get quality lenses to go wide enough. I ordered a 10mm prime lens designed for 16mm, and even that lens with 2/3" format is not that wide (in 16mm, it's super wide). To get wide-angle in 1/2" you're basically stuck with industrial video lenses (of extremely questionable quality) or super-expensive 16mm primes.

And the cheap interface is a huge, huge thing, especially for someone such as myself who wants to shoot outside. Also, Sumix is commited to similar interfaces for future products. Much like the SI-1300 is "practice" for Obin before the Altasens comes out, so is the SMX-150c for me.

Just curious, what interface(s) are you putting on the Altasens design?

- ben

Obin, how do you go about eleminating hot spots? Is this a consistent problem?

Adjusting the gamma shouldn't be a large problem. I'm just not sure I fully understand how you can get crushed blacks from an overexposed image. Is it because you have to pull the highlights down so much?

Ben:
The altasens will be first on camera link since its top end is about 300MB/sec. We will then do a gigE version but should include at least packing if not compression.

There are Schneider Cinegon 8mm lenses at 2/3". Not cheap but none of the good glass is unless you buy it used.

I will be curious how you fare on the USB 2.0 because we have them too and have written them off for cinematography.

Steve,

With 10bit transfers (and possibly some compression? it's not clear) USB2 should be fine for 720p at 24mhz. It's FW800 that I'm really looking forward to..

Funny you should mention Scneider Cinegon -- the 8mm was a little out of my league, but I have a used (well, old -- I don't think it was ever used) 10mm Cinegon on the way. Supposedly it covers all the way to Super16, so maybe it's an older model...

Good to hear about GigE -- will the camera get its power over ethernet as well?

- ben

hotspots are jsut areas in the image that have above 100% exposure...it's what you shoot not a "spot" on the image

who's going to have the first working altasens camera?? and when? and for how much? any guesses?

check out the dynamic range in this image! WOW NO lights on inside at all and you can still see the window sill if you push it...but see the streaking? that is what I am talking about...take the gamma all the way to 2.6 or so and you will see what I mean...

http://obin.weet.us/16bit_color_tiff.tif

Steve, i wanted today order a SI-1300-Set, but the rolling shutter problem will not go out of my head. You know, we need the camera for a movie project. Shoot with 48fps, but only use every second frame is also not like a movie camera. Okay, in a movie camera (with 24fps) the exposure time is about 1/50 sec., but not the exposure time is the problem. It is the slow rolles shuttet. A mechanical shutter in a movie camera move in a different way and is faster. The shutter diameter is 3-5 times larger then the frame size. So from a whole one turn it need only a angle of round 15 degree to close (or open) the picture window. This time is only a 1/24 of one frame (one turn=360degree, so 15degree = 1/24).
1/24 of one frame, not 1/24sec like the SI-1300. A movie camera shutter rolls (at 24fps) in 1/576 sec. This is 24 times faster! This is a enormous difference and i think definitely rolling shutters are not usefully to shoot a movie with it.

@Ben, you have no email here, can you contacted my, please

Rai...look at the image below:

http://obin.weet.us/gamma 2.4.tif

dude...would YOU shoot a feature film with that much artifacting in the darks?

that is a gamma of 2.4...LOTS of dynamic range and LOTS of overexposure artifacts in the blacks..

Rai...I sent you 3 files...they all came back...if you want images then you need to deal with your email account!!!!

don't beg me for stuff just to have it sent back ;)

Rai:
I don't think I understood what you said. There are two separate issues in a rolling shutter camera. The first is exposure which can be set from a maximum of a frame time to a minimum of a couple of rows. This will do as you expect - shorter frame times yield less light in but less motion blur. Second is the rolling shutter artifact - the time difference from the readout of the top of frame to bottom. This is either 1/24th sec or 1/48th sec if you drop every other frame (which limits the max exposure and *may* cause more smearing). I think the max 1/48th sec exposure might be what you referred to.

I'm going to remind everyone that the excitement on the Altasens is still over a rolling shutter sensor - running at 24/30/48/60fps.

painting RAW:

http://obin.weet.us/painting.tif

painting with gamma set at 2.2 and some cc to make it standout:

http://obin.weet.us/painting gamma 2.2 some cc.tif

@Obin, first thanks for the images (email). My people, also in the post, say the RAW images are okay.

---->http://obin.weet.us/gamma 2.4.tif

dude...would YOU shoot a feature film with that much artifacting in the darks?<----

No, but we would also not shoot with a 35mm ARRI this view. Obin, i think there is a differently "look" we need. You compare all images with a normal video camera. But i dont want video look. I love cinema, and so i love your earlier images.
But my main problem now is the rolling shutter

what "look" are you going for ?? High Contrast? low contrast? bright colors?

Steve,
sorry, i mean rolling shutter artifact. You said it: The time difference from readout of the top of frame to bottom is very slow. It lasts a whole frame. And that is exactly the problem. At 24fps its 1/24th sec. At 48fps its 1/48th sec. It is much to slow. A mechanical shutter in a movie camera do this 24times faster.

Obin,
i not the man who make the post.
I can only say what i like. It is more movie "look" than video "look"

video = TV-News, Sports or so.
Movie = The X Files

http://obin.weet.us/outdoors-1.wmv

gamma about 2.0 and minor CC for a natural tone

Ahh, now I understand!! :-)

So that's how camera manufacturers get around the rolling shutter artifacting problems-the chip is always running at 60Hz (for NTSC), it's just the exposure time is different for the rows, but the chip itself is always reading out at a fast enough "frame-rate" to eliminate any rolling shutter artifacts. And that's why you can't get the shutter slower that 1/60th of a second (in normal mode) on an NTSC camera.

Now the progressive cameras like the DVX100 though can do 1/30th of a second shutters, and they supposedly shoot at 24fps. I haven't seen any rolling shutter artifacts with that camera, and again, I think a lot of the problem has to do with lack of motion blur. When the shutter is all the way open I'm used to seeing much more motion blur than what I'm seeing in these samples. So I'm not sure if the integration time is long enough or not, but I'm figuring that the more motion blur in the frame, the less you're going to see any rolling shutter artifacts.

BTW, how come you can't have the chip read out in 1/48th of a second an then blank for 1/48th of a second? I mean suppose you wanted 32fps or 33fps, how would you do that and still maintain the /148th of a second shutter since they don't evenly divide into each other?

rolling shutter is a thing of CMOS I think..I have never seen an issue with CCD chips..and YES JVC etc will run the Altasense at 60mhz ALL THE TIME and take every other frame to tape for 30fps etc

The JVC page mentioned it had a max rate of 75mhz -- maybe they're running at that speed all the time.

Rai, what do you need?

Jason and Obin,
it is not only the motion blur. A movie have also motion blur and i like it. But a movie camera have not the rolling shutter artifact problem.
(Oh my bad english...) If you have strings (up to down), or just the manhatten skyline and you move the camera (left to right) the first line in the sensor is readout, than a little time later the next line, and so on, but in the meantime the camera move on. The position is not the same, because it takes 1/24th sec from the first line on the top to the last line.
The picture "swings". I hope you understand

With global shutter, you have also motion blur (and i like this), but you will dont have this artifact swinging problem.

Ben, i think i like your camera. We have some ideas to change the interface and other things, so we can use it (with 10bit and in global shutter mode) next days. Please email...

Rai, the interface is totally fixed -- it's USB2. And Sumix is working on 10bit software as we speak. What exactly do you want to do?

IBIS-5 vs Micron 1.3Mpix
 

My boss did a pair of images of the IBIS-5 and the Micron 1.3Mpix using the standard XCAP tools for image enhancement. The IBIS-5 was run in global shutter mode since the color is better that way. It was run at a slower clock to allow for sufficient exposure time.

http://siliconimaging.com/Samples/SI....3%20GG1.2.jpg

http://siliconimaging.com/Samples/SI....3%20GG1.2.jpg

Rai:
You have it. Motion blur and rolling shutter artifacts are totally separate effects other than their visual interaction. The Altasens can be run at any rate up to 60fps.

More on the rolling shutter beast:
The 60fps of NTSC was done with interlacing. First you display a frame of even lines in a 60th of a sec and then a frame of odd. Any rolling shutter effects would be jagged that way. CCDs have been available for years with either interline transfer or full frame transfer - both ways of capturing a full frame at once.

that's why I like the Micron......WAY more color then the IBIS

Steve,

I Level'd the 1280 image and boosted the chroma by 1.25x -- of course it looks kind of rough because the input was a jpeg, but you can get a sense.

si1280corrected.jpg

I had one version that looked essentially the same as the Micron image, but i figured what the heck -- I'll up the color a little bit more and white balance it a little better. (It's tough because the flourescent is really blue)

- ben