Interpolation: Sony vs HVX at DVinfo.net

John Poore · September 22nd, 2005, 01:23 PM

I know the Sony FX/Z cameras use interpolartion to achieve full HD spec, I think the baseline for FX1 is 1080x540, and its pumped up from there with no real picture loss.

Now it -seems- this upcoming HVX appears to interpolates even more according to forums and has even less basic chip resolution which, it is said, results in chroma loss.

Is this finally a chink in the armour of Panasonic's mighty HD 4:2:2 contender. Does this mean the FX can producer a better picture even with 4:2:0 colour?

Barry Green · September 22nd, 2005, 02:21 PM

The FX and Z1 don't "interpolate" at all, and neither will the HVX. Interpolation implies manufacturing pixels that aren't there. These cameras all use spatial-offset CCDs which allow them to sample true resolution off of a combination of three larger-pixel chips. The tradeoff is that you can't get full 4:4:4 sampling, but that's pretty much irrelevant because the recorded format is 4:2:2 or 4:2:0 anyway. So you get to use bigger pixels, get better low-light performance better dynamic range, and a better signal-to-noise ratio, while getting the same luma resolution as a "native resolution" chip. Sounds like not a bad tradeoff to me!

"interpolation" is what PhotoShop does when you resize a picture. Spatial Offset (aka "pixel shift") is nothing of the sort. It's a totally valid technique which has been used in CCDs for years and years.

John Poore · September 22nd, 2005, 03:11 PM

Ok I should have meant pixel shift. Thanks for the clarification Barry.

Going back to the difference apparent between the FX and HVX, does this imply a difference in quality, in particular chroma, in which the Sony has the upper hand as some of other forums are implying?

Barry Green · September 22nd, 2005, 06:12 PM

I can't see how anyone could be claiming the Sony to have better chroma recording than the HVX. The Sony records 720x540 chroma, the HVX is 640x1080. Do the math, the HVX is recording about 80% more chroma.

The Sony has 960-pixel-wide CCDs. The HVX will likely have *at least* 960, if not 1280.

The Sony has 1080-pixel tall CCDs, but throws away half its vertical chroma res. Whatever the vertical res of the CCDs are on the HVX, it will retain all that resolution.

When you say "other forums", I haven't seen anyone postulating this -- can I just guess as to which forum you're referring to? And would the particular person making the claim be the same one who's always tilting at windmills and manufacturing outrageous arguments in an attempt to discredit anything non-Sony?

John Poore · September 23rd, 2005, 03:29 AM

I must have got confused, or read a post that was confused!

Thanks for the clarification Barry. All these big numbers with HD :}

Kevin Shaw · September 23rd, 2005, 08:49 PM

The Sony FX1 & Z1U have three 960x1080 sensors that are offset from each other to generate the "pixel shifted" luma resolution of 1440x1080. We don't know for sure what the HVX200 will have yet, but on the "HD for Indies" site there's speculation that it will be something similar -- perhaps 960x720 or 1280x720 with pixel shifting. To the extent that any of this matters, it's worth noting that the new Canon HD camera may have true 1440x1080 sensors, which would be a point in Canon's favor.

The big problem with the HVX200 will be that it's recording options are limited and expensive for anything other than short recording sessions, with a matching issue regarding how to permanently archive the source footage. People who really want to use this camera will find ways to deal with this, but it's not going to be a camera for casual users.

September 22nd, 2005, 01:23 PM	#1
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	Interpolation: Sony vs HVX I know the Sony FX/Z cameras use interpolartion to achieve full HD spec, I think the baseline for FX1 is 1080x540, and its pumped up from there with no real picture loss. Now it -seems- this upcoming HVX appears to interpolates even more according to forums and has even less basic chip resolution which, it is said, results in chroma loss. Is this finally a chink in the armour of Panasonic's mighty HD 4:2:2 contender. Does this mean the FX can producer a better picture even with 4:2:0 colour?

September 22nd, 2005, 02:21 PM	#2
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	The FX and Z1 don't "interpolate" at all, and neither will the HVX. Interpolation implies manufacturing pixels that aren't there. These cameras all use spatial-offset CCDs which allow them to sample true resolution off of a combination of three larger-pixel chips. The tradeoff is that you can't get full 4:4:4 sampling, but that's pretty much irrelevant because the recorded format is 4:2:2 or 4:2:0 anyway. So you get to use bigger pixels, get better low-light performance better dynamic range, and a better signal-to-noise ratio, while getting the same luma resolution as a "native resolution" chip. Sounds like not a bad tradeoff to me! "interpolation" is what PhotoShop does when you resize a picture. Spatial Offset (aka "pixel shift") is nothing of the sort. It's a totally valid technique which has been used in CCDs for years and years.

September 22nd, 2005, 03:11 PM	#3
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	Ok I should have meant pixel shift. Thanks for the clarification Barry. Going back to the difference apparent between the FX and HVX, does this imply a difference in quality, in particular chroma, in which the Sony has the upper hand as some of other forums are implying?

September 22nd, 2005, 06:12 PM	#4
Barry Green Barry Wan Kenobi Join Date: Jul 2003 Location: North Carolina Posts: 3,863	I can't see how anyone could be claiming the Sony to have better chroma recording than the HVX. The Sony records 720x540 chroma, the HVX is 640x1080. Do the math, the HVX is recording about 80% more chroma. The Sony has 960-pixel-wide CCDs. The HVX will likely have at least 960, if not 1280. The Sony has 1080-pixel tall CCDs, but throws away half its vertical chroma res. Whatever the vertical res of the CCDs are on the HVX, it will retain all that resolution. When you say "other forums", I haven't seen anyone postulating this -- can I just guess as to which forum you're referring to? And would the particular person making the claim be the same one who's always tilting at windmills and manufacturing outrageous arguments in an attempt to discredit anything non-Sony?

September 23rd, 2005, 03:29 AM	#5
John Poore Regular Crew Join Date: Nov 2004 Location: Johannesburg Posts: 107	I must have got confused, or read a post that was confused! Thanks for the clarification Barry. All these big numbers with HD :}

September 23rd, 2005, 08:49 PM	#6
Kevin Shaw Inner Circle Join Date: Sep 2004 Location: Sacramento, CA Posts: 2,488	The Sony FX1 & Z1U have three 960x1080 sensors that are offset from each other to generate the "pixel shifted" luma resolution of 1440x1080. We don't know for sure what the HVX200 will have yet, but on the "HD for Indies" site there's speculation that it will be something similar -- perhaps 960x720 or 1280x720 with pixel shifting. To the extent that any of this matters, it's worth noting that the new Canon HD camera may have true 1440x1080 sensors, which would be a point in Canon's favor. The big problem with the HVX200 will be that it's recording options are limited and expensive for anything other than short recording sessions, with a matching issue regarding how to permanently archive the source footage. People who really want to use this camera will find ways to deal with this, but it's not going to be a camera for casual users.