|
|||||||||
|
Thread Tools | Search this Thread |
March 4th, 2007, 09:25 AM | #1 |
Trustee
Join Date: Feb 2006
Location: Niagara Ontario Canada
Posts: 1,121
|
Pixel shifting? What is it exactly?
What does Pixel shifting really mean? I know that the HVX has it, but how does it differ from other hd cameras like the Z1u or the FX1?
|
March 4th, 2007, 09:33 AM | #2 |
Inner Circle
Join Date: Apr 2003
Location: Aus
Posts: 3,884
|
from my understanding of it, its an in-cam interpolation algorythm..
|
March 5th, 2007, 09:34 PM | #3 |
Major Player
Join Date: Jan 2007
Location: Pinellas Park
Posts: 232
|
Pixel Shifting in HVX 200
Basically it's shifting the green CCD 1/2 pixel biaxially, both H and V. This increases the 960 x 540 progressive chips to HD resolution. Panasonic's thought is larger pixels equal greater sensitivity, producing adequate results in low light from the 1/3rd inch CCDs.
As far as other cameras go, most achieve or are close to achieving hd resolutions. To compare, HVX200 has 500,000 pixels and canon XHA1 has over 1,600,000 pixels. The canon achieves the necessary 1440 x 1080i resolution for HDV. Right off you would assume the camera from canon to be the sharper camera. However, HDV compresses the video 25mb/s; whereas, the HVX200 uses DVCPROHD compression at 100mb/s. All this means is that the HDV camcorders suffer more when there is fast motion in the image because of compression artifects (usually in the form of macroblocking). However, if you were to put these cameras side by side, you would be hardpress to pick an outright winner. The canon looks a bit more washed out but sharper than the Panny. Each has its pros and cons. Some prefer the soft look and richer colors of the HVX200, while others like the sharper image from the XHA1. Of course, HDV camcorders compress audio as well; whereas, the HVX200's DVCPROHD codec produces uncompressed audio. Another advantage of the HVX200 is variable frame rates. Of course, the canon has a longer lens. Last edited by John Bosco Jr.; March 5th, 2007 at 10:13 PM. |
March 7th, 2007, 06:30 PM | #5 | |
Inner Circle
Join Date: Jan 2006
Posts: 2,699
|
Quote:
Since the human eye is more sensitive to luminance resolution than chrominance, and most TV systems have more limited chrominance resolution anyway, it should generally be seen as a good thing. |
|
March 7th, 2007, 06:38 PM | #6 |
Obstreperous Rex
|
Pixel Shift is a resolution boost that has been around for a very long time, and yes it is a Good Thing (beware of various marketing tactics that try to portray it as anything else). If I recall correctly, Panasonic invented it, but most all three-chip camcorder manufacturers use it these days. It is the rare exception for a three-chip camcorder *not* to use Pixel Shift, such as the JVC Pro HD series GY-HDxxx. I've described it several times before in the past, but there's a good technical write-up from Panasonic floating around somewhere... stand by while I dig it up.
|
March 7th, 2007, 06:52 PM | #7 |
Obstreperous Rex
|
Okay, here it is; the best description of Pixel Shift that I know of.
Go to this page: Learn about Panasonic's AG-HVX200 Under the "Support and Resources" tab, click the link at the bottom of the left column on that page, entitled "Tech Paper - AG-HVX200's Advanced Progressive CCDs" -- your description of Pixel Shift is found in that PDF document. As I said, most all three-chip camcorders use it. Everything by Canon, everything by Sony, everything by Panasonic. Some earlier products from JVC. Hope this helps, |
March 8th, 2007, 05:00 AM | #8 |
Major Player
Join Date: Jan 2007
Location: Pinellas Park
Posts: 232
|
Are you sure "everything by Canon?" The XHA1, G1 and XLH1 all have native HDV resolution chips. I believe Canon abandoned pixel shift with the XL2. Unless I'm missing something. It's funny that they did that, though, because they used pixel shift with success in the XL1/1S cameras.
|
March 8th, 2007, 07:53 AM | #9 |
Inner Circle
Join Date: Apr 2003
Location: Aus
Posts: 3,884
|
from my understanding, Canon used Panasonic sensors for their XL/GL series cameras
|
March 8th, 2007, 10:51 AM | #10 | |
Major Player
Join Date: Mar 2005
Location: UT
Posts: 945
|
Quote:
These cameras do have all the native pixels needed for the actual recording format, but rely on less aggressive pixel shift in order to achieve full raster processing in-camera. |
|
March 8th, 2007, 10:02 PM | #11 | |
Obstreperous Rex
|
Yes, I am sure, everything by Canon.
Quote:
|
|
March 9th, 2007, 04:10 AM | #12 | |
Major Player
Join Date: Jan 2007
Location: Pinellas Park
Posts: 232
|
Quote:
|
|
March 9th, 2007, 04:23 AM | #13 |
Major Player
Join Date: Jan 2007
Location: Pinellas Park
Posts: 232
|
HVX200 vs. Full Rez 1/3rd inch HD Chips in low light
I have a question about sensitivity. Maybe it has been addressed before, but here it goes.
It is Panasonic's theory that full HD resolution on 1/3rd inch chips would not make the camera sensitive enough. So how does the HVX200 compare with the XHA1/G1/XLH1 in low light situations? |
March 9th, 2007, 09:45 AM | #14 | |
Inner Circle
Join Date: Apr 2003
Location: Aus
Posts: 3,884
|
Quote:
|
|
March 10th, 2007, 02:26 PM | #15 | |
Major Player
Join Date: Mar 2005
Location: UT
Posts: 945
|
Quote:
As far as Panasonic's theory goes, it's surprising that the A1 has just over 1.5 MP and the HVX has just over 500K, yet they are similarly sensitive. (according to Adam Wilt's tests) By all rights, the HVX should have much better sensitivity and less noise because its pixels are physically larger. I guess this is where theory can go out the window. I know that the A1's interlace CCD's give it a bit of a sensitivity advantage over progressive, but I'm sure it's not completely apples to apples. They're simply different sensors with different capabilities. |
|
| ||||||
|
Thread Tools | Search this Thread |
|