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Alternative Imaging Methods
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Old September 9th, 2004, 11:56 PM   #1126
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Only 493, would the PAL version get 540?

I was wondering, like the Canons and new Sony, is it possible to offset the CCD's to get interpolated 854*480 picture to match the widescreen flat TV's (using anamorphic adaptor)? Or further to archieve interpolated square pixel resolution equivalent to widesceen 2.39:1 format (what would that be 480*1148, 540*1291 PAL)? Once it went through upscaling film conversion it would be perfect for cinema production.
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Old September 10th, 2004, 01:00 AM   #1127
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Without modification, you can't move the CCD's for a specific configuration. However, in the DVX the CCD's are already offset, i beleive specifically the green sensor is offset somewhat. My software doesn't yet take this into consideration, but it is very probably that I can get an even better HD image by somehow using the pixel shift.

Juan
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Old September 10th, 2004, 11:32 AM   #1128
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Juan, is it possible to flip the image inside the mod? Many people are building their own Mini35 systems and these usually project a flipped image on the CCD. I am building one of my own for steadycam work, because the PSTechnik adaptor is just too heavy.

Pretty please with sugar on top,
Chris
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Old September 10th, 2004, 11:55 AM   #1129
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Yup, it already does that.
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Old September 10th, 2004, 11:59 AM   #1130
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Juan... many moons ago you toyed with the idea of putting a cooling device (a'la astronomy) behind the CCDs to reduce thermal noise.

Are you still toying with that idea in the future or do you have your hands full w/too many other things?
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Old September 10th, 2004, 12:17 PM   #1131
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Hi,

Depending on the mechanical construction, it could be as simple as strapping a peltier stack on the back of the block carrier and cooling it. Noise would be an issue, as would battery consumption. However, this may be worth pursuing, particularly in light of the poor low light performance with this modification - well, no poorer than it ever was, but you get my drift. I'll go out on a limb and bet that at least the two LSB of that 12-bit data is noise, and probably three or four.

Phil
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Old September 10th, 2004, 05:49 PM   #1132
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Hello there !
Sorry Juan and everyone, but I am way too lazy to search the whole thread
in order to find out if DVI is still in or not.
I wish it is, cause those new Apple displays sure are tempting monitoring creatures.
Keep it up
Emmanuel
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Old September 12th, 2004, 11:01 PM   #1133
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If you cool the CCD's be carefull of condesation build up on the cooled surfaces. PC's were having that problem with their peltier coolers, the water would short out parts of the board, I don't know how they over came it.
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Old September 14th, 2004, 12:34 PM   #1134
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<<<-- Originally posted by Juan P. Pertierra : 773x494 pixels per frame, 36-bits of color information per pixel. -->>>

At that resolution, if my math is right, you're look at about 1.6 megs per frame. Even at 24p, that's nearly 40 megabytes per second.

Have you actually found any USB2 drives that can actually sustain that? Even the best USB2 drives I've seen have only sustained about half that in benchmarks.

Has there actually been any testing of "full motion" capturing instead of single frames?
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Old September 14th, 2004, 12:37 PM   #1135
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I have done full motion capture directly to a Western Digital IDE drive, i listed the model number here before but it was nothing fancy, i bought it at circuit city.

Whether a specific USB2.0 hard drive enclosure supports the maximum speed of USB2.0 that remains to be seen. My LaCie drive works fine.

Juan
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Old September 14th, 2004, 02:59 PM   #1136
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Hi,

It's probably worth noting here that a filesystem implemented in firmware doesn't suffer from the same problems as one that's part of an operating system - mainly that it's one of a large number of tasks, each of which is trying to claim bus and processor time. This filesystem doesn't even need to know about directories, only needs to know how to write one kind of file, and many other shortcuts which will increase its speed.

That said, I'm fairly surprised that a standard IDE drive will write 40Mb/sec, even in raw sectors.

Phil
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Old September 14th, 2004, 08:16 PM   #1137
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A quick question to clear something up, if you don't mind, Juan: when you say you're using USB 2.0, is that as a camera-to-drive interface, or drive-to-computer? Or both?

I was concerned (like I could afford this setup in the first place) that USB 2.0 wouldn't be fast enough to capture directly from the camera without dropping frames. Capturing regular DV footage from my camera directly to a USB 2 LaCie drive started dropping frames if I so much as opened a window...though I suppose there are other factors at play in my situation.

What exactly will this USB connection be used for?
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Old September 15th, 2004, 01:18 AM   #1138
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Over at the 10-bit 4:4:4 and HD cinema camera threads they have discovered drives that do 50MB/s sustained and even one that does 72MB/s. Problem is I can';t remember what they are (and have to go out now), but they're there. If you want to do a search, I think Juan M. M. Fiebelkorn mentioned them about a month or two back, and they were Western Digital. These are likely to be server drives.
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Old September 15th, 2004, 01:44 AM   #1139
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USB2.0 is fast enough to transfer all the data. The bottleneck is when you introduce software based systems such as a computer. Phil makes the point about having only hardware interaction.

For example, my desktop computer is about 2 years old. If I tried to capture the full data in real time using standard functions i'd run into trouble. However, the experimental digital capture card I'm using has specialized drivers which use DMA and use a direct path between the PCI Bus and the hard drives. I can capture full motion up the point where my 120GB drive is full with no problems whatsoever.

About the pixel shift...it's not really a 'shift' of the CCD's per-se. It rather seems that the green CCD is placed farther away from the prism by a tiny amount such that there is a larger projected image on the chip, and the optical information that lies between elements in the other CCD's lies ON elements in the green sensor. Afaik the sensors are not moved in the x/y direction willingly.

And no, the HD images I have posted do not take advantage of the pixel shift. I actually 'eliminated it' by resizing the images to match and aligning them which will actually yield worse detail. I'm still not sure about what procedure to use to take advantage of the shift....it seems like I would have to up-rez R,G,B channels separately in a bicubic manner, align them and THEN apply S-spline.

Anybody have a suggestion?

Juan
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Old September 15th, 2004, 03:37 AM   #1140
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Use the same demosaiking algorithms used for single sensor cameras.
Just need some little modifications to work with that structure.
The drives Wayne is talking about are the WD Raptor.
They are not server disks.
SATA interface, 10,000 RPM, 72 MB/s.
Two flavors , 36 and 74 GB.
Around $200 (74GB).
Juan M. M. Fiebelkorn is offline  
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