4:4:4 10bit single CMOS HD project

[Ben Syverson]

Bicubic is crap. That's probably why. :) Bicubic sharpens (edge-enchances) the image as it interpolates. I don't know about you, but nothing says "video" to me like a sharpened image.

Much better is spline interpolation. There's also Mitchell, Catmull-Rom, Sinc, etc. Check out this shootout of the Cubic, Spline and Sinc algorithms for a visual idea of the differences between them.

The green channel really doesn't need anything but linear (not even bilinear) interpolation, since there's twice as much information than R or B. Spline interpolation would be nice on the R or B channels, but personally it's not worth the processing time to me unless it's a greenscreen shot...

[Jason Rodriguez]

Hmm . . .

that spline interpolation does look nice :-)

I'm already doing your linear filter on my G5 in less than a second, how much longer do you thing it would be if you made an optional interpolation plug-in that did spline interpolation on all three channels for green-screen type applications? For the highest-quality work, even if I'm at 4 seconds per frame, I don't think that's too high a price to pay. A good-quality algorithm like you have right now for quickie stuff, and then for the stuff that we either plan to blow-up big or to use for special effects-and I was hoping that was something these cameras could be used for since they are uncompressed-or for simply the highest quality, a good spline-based interpolation algorithm that processes all three channels: red, green (I know you said the green doesn't need it, but if we're going to take the computational hit, we might as well go all-out), and blue, so that there are no compromises.

Does that sound like a good idea?

[Obin Olson]

Ben I think your right on CAPTURE NOW and do your compression later..for now anyway...this will allow for a 1.5ghz 7watt VIA cpu on a itx 5" x 5" mainboard to be all we need for speed...and then a plugin/background process that does compression ...this is the first approach I think I will take anyway


we now have raw color images showing on screen with our capture software and full camera control working...next up is disk writing...and doing multi threading

I think i will use the ITX mainboard with the fastest VIA chip we can get and 2 SATA disks for capture of (I hope) 60fps 1280x720 8bit and 48fps 1280x720 10bit

I placed the order for a 1024x768 touch screen and am waiting for it to arrive

BTW we have named the capture ware CineLink..what do you guys think?

can we get 60fps from 8bit ?? what will the datarate be?

[Ben Syverson]

Yeah -- that's what I'm planning -- within a couple versions of linBayer I'll build in a popup menu for the R&B interpolation with Linear and Spline.

The reason why it doesn't make sense to do spline interpolation on the green is that we're doing all this logic-based stuff on top of the interpolation. So the quality of the initial interpolation doesn't really matter.

But a 16 (4x4) pixel spline interpolation will be super nice on the R&B channels...

[Jason Rodriguez]

BTW we have named the capture ware CineLink..what do you guys think?

Naw,

how 'bout "GorillaCam" ;-)

Seriously, CineLink does sound nice, and have some sort of professional ring to it.

[Ben Syverson]

Do a google search for CineLink -- ten bucks says its a registered trademark. Why not come up with something unique?

Like GorillaCam/GuerrilaCam? :)

[Jason Rodriguez]

The reason why it doesn't make sense to do spline interpolation on the green is that we're doing all this logic-based stuff on top of the interpolation. So the quality of the initial interpolation doesn't really matter.

Are you sure? As of right now, I don't think I could pull a nice green-screen from the linBayer plug-in. Not without doing a "blur" filter of some kind first to smooth out that faint gridding pattern. I know you've incorported the other logic-based stuff to reduce the gridding, but greenscreening has a nasty habit of pulling out all the invisible artifacts in a frame.

For good green-screening, you'll want the best possible algorithm on the green-channel without cutting corners.


Looks like CineLink is some sort of Bosnian film festival.

[Obin Olson]

good name but it is NOT going to LOOK as good as WinAmp...I don't have money for SEXY UI stuff!!! LOL....well maybe i can feed the programmer lots of Oreo's and weed in exchange for a SEXY UI!? ;)

hahhah:
http://sff.ba/10SFF/program/eng/cinelink.htm

oh well,,,,I guess we will just share names!

[Ben Syverson]

Jason,

A 0.5 pixel (or even 0.25) is all you need to erase those artifacts -- just apply it after linBayer and before the keyer.

The reason why I don't build any softening into linBayer itself is that it's designed to deliver the sharpest possible image. Unfortunately, if your image is noisy, the logic has a hard time putting the image back together.

The options we built in should kill 90% of the "gridding," but the remaining 10% is the price you pay for superior sharpness...

- ben

[Jason Rodriguez]

A 0.5 pixel (or even 0.25) is all you need to erase those artifacts -- just apply it after linBayer and before the keyer.

I know, but I was just thinking that it wouldn't be that much harder to incorporate spline interpolation (if it's that much better than linear) into the green channel while you're also offering that option for red and blue-like I said again, just so there's no compromises, added blur filters, etc, we can know that each channel is getting the best possible interpolation algorithm applied to it.

[Ben Syverson]

CineLink(tm) is security software for DLP digital projection. The technology was created by TI. Check out this product page (search in the page for CineLink):

http://www.dlp.com/about_dlp/about_d..._dlpcinema.asp

[Obin Olson]

Ben, do you need more RAW footage to test with? I am not sure what I have posted on this site for download..let me know if you you need it...do you think we could use your bayer filter in our capture software? maybe for some sort of trade ;) or??

it will work on RAW files right? so we could use it as we convert from RAW data on disk into a format like avi or others?

[Ben Syverson]

Obin, I'm using some of the images you've posted here, and I'm getting some of your images via Jason. :) I've also been working with footage from other cameras to be sure that I'm not over-customizing the software.

I've tested it on both RGB and RAW images, and once my camera gets here (tomorrow? thursday?) I'll finish up the last remaining things I want to do with it.

I'd be happy to pass along my algorithms as long as your software winds up being 100% free. If you charge for it, we'll have to work something out.

Actually, if you could shoot a test in front of a greenscreen (flourescent green posterboard from the grocery store is fine -- don't worry about the lighting too much) we could see how my software fares with keying... all I need are a couple RAW 16-bit B&W bayer images.

Jason,

What I'm saying is that even if we do spline interpolation for the G channel, we still have the logic-based de-zippering going on. So we'll have a beautiful spline interpolated G channel (with zippering) which we'll then etch over with linear patterns like we do now. The result will be the exact same amount of gridding... Having written a few keying algorithms, I don't think a post-blur will be absolutely necessary, but it will depend on how poorly the shooter has calibrated the G1 and G2 gain. Getting the green gains lined up is key with linBayer...

[Jason Rodriguez]

Yah, the gains on the camera,

that brings up a good point.

Once you have the G1 and G2 gains balanced, do you have to adjust them for each scene, or is it a set-once and forget type thing?

[Ben Syverson]

That I don't know yet. Steve? Obin?