Tech Note Why The Panasonic Had Poor Resolution

Mr. Blonde said:
From what I recall, Kaku's charts showed a higher diagonal than vertical or horizontal.

Is that what u mean ullanta?
Click to expand...

Exactly! I'd like to see if this is common, or a peculiar strength of the HVX. I haven't sat down to work it out yet, but it seems to me that with pixel shift, Horizontal and Vertical may not be the optimum resolution angles. Maybe Bob Diaz can help us out?
 
The ccd will be 960x560. This is close to the chroma resolution of DVCPRO HD. The problem will be the luma resolution which all b&w test charts shows. Panasonic has to make some uprise conversion to got the corrects luma resolution.

I start thinking Panasonic has made a misstake when they desided to save money with a smaller ccd.
 
That does not sound like valid information Berga. The format has 640x1080 chroma. DVCPROHD is not 1920x1080 4:2:0 or whatever you used to calculate 960x560, it is 1280x1080 4:2:2.
 
limo991 said:
That does not sound like valid information Berga. The format has 640x1080 chroma. DVCPROHD is not 1920x1080 4:2:0 or whatever you used to calculate 960x560, it is 1280x1080 4:2:2.
Click to expand...

Yes, 4:2:2 is half chroma sampling horisontal and half chroma sampling vertical. That is, 640 x 540. Using pixelshift both horisontal and vertical. With 960 x 560 and pixel shift both horisontal and vertical, You can reach a resolution of 1280 x 720 with some safty marginal.

But DVCPRO is also 960 x 720. This is used in most DVCPRO HD equipment which latter upsampling the picture to 1080i. This is the way Varicam works. DVCPRO HD is first a 720p format and secon a 1080i format.

One clue to the small resolution of the ccd is the higher light sensity HVX has compare to the other sub $10000 cameras. All these cameras has a 1/3 inch ccds. If Panasonic not has a magic formula for ccd:s which creates an huge increase in light sensity, they must have larger pixels on the ccd:s. Larger pixels indicates less pixels per square mm.
 
Berga said:
Yes, 4:2:2 is half chroma sampling horisontal and half chroma sampling vertical. That is, 640 x 540. Using pixelshift both horisontal and vertical. With 960 x 560 and pixel shift both horisontal and vertical, You can reach a resolution of 1280 x 720 with some safty marginal.

But DVCPRO is also 960 x 720. This is used in most DVCPRO HD equipment which latter upsampling the picture to 1080i. This is the way Varicam works. DVCPRO HD is first a 720p format and secon a 1080i format.

One clue to the small resolution of the ccd is the higher light sensity HVX has compare to the other sub $10000 cameras. All these cameras has a 1/3 inch ccds. If Panasonic not has a magic formula for ccd:s which creates an huge increase in light sensity, they must have larger pixels on the ccd:s. Larger pixels indicates less pixels per square mm.
Click to expand...

4:2:2 is 2 chroma pixels for every 4 luma pixels. Horizontally only.
DVCPROHD 1080 is 1280x1080 luma and 640x1080 chroma.
DVCPROHD 720 is 960x720 luma and 480x720 chroma.

The sensitivity would have to be judged independently of all parameters in order to reach a conlusion about pixel size. It's different cameras, different support circuitry, different everything. The gain setting does not represent the real gain applied. I could program the camera software to have only negative gain settings. Would everybody think it is very sensitive because 0db is bright? It is also noisy! Many camera manufacturers play games with gain offsets. Sony is on the opposite side. Gain appears to be true gain and darker than the competition at 0db using sensors of approximately same size.
 
Limo 991 is correct. That's precisely what I was thinking. If the chips are the size of the total chroma res, they're 640x1080, Berga is thinking HDV, which is 4:2:0.
 
ullanta said:
Exactly! I'd like to see if this is common, or a peculiar strength of the HVX. I haven't sat down to work it out yet, but it seems to me that with pixel shift, Horizontal and Vertical may not be the optimum resolution angles. Maybe Bob Diaz can help us out?
Click to expand...


I hate to say this, but I'm a bit like a dog chasing his tail and running in circles. :)

The several models I've tried, have real problems (too many unknown factors) and NOTHING agrees or provides support. :cry:

In a few days, I'll post a technical note with a touch of humor showing how the number is next to impossible to pin down without additional information.

Bob Diaz
 
doccutter said:
Limo 991 is correct. That's precisely what I was thinking. If the chips are the size of the total chroma res, they're 640x1080, Berga is thinking HDV, which is 4:2:0.
Click to expand...

Sorry, I does not thinking at all. But this is figures for the sampling of DVCPRO HD.
1080i50 has luma sample of 1440x1080 and chroma of 720x1080.
720p is 960x720 luma and 480x720 in chroma.


Still the it is possibly to made a ccd which deliver 720 which will be upsample to 1080. This is the technic Panasonic use in their non-varicam dvcpro-hd camera, which has a 720 ccd which is upsample to 1080.
 
You must log in or register to reply here.
Back
Top