Shooting 720p vs 1080p (720 upscaling to 1080?)

A

AdrenalineSleep

Member
It is my understanding that the sensor for the HMC150 is 720p and that the camera upscales the image to 1080p. Is this correct?

If this is true then, what is the difference between shooting in 720p and upscaling the final product to 1080p or just shooting 1080p natively?

I just shoot everything 1080p and figure I could export to 720p if necessary. Besides say, frame rate differences, why shoot in 720p if 1080 is an option?
 
I use 720 exclusively because:
- Razor-sharpness isn't critical for my needs (most clients don't have massive TVs yet, and I do a lot of web-bound video)
- 1080 is larger file sizes (I have heard)
- 1080 is rougher on your computer specs (I have heard)
- I like 60 fps and I don't like interlacing - an option only available in 720 mode.
 
while i haven't tried uprezzing, i just did a day of pixel peeping comparing 1080 to 720 and found 1080 to produce slightly sharper images.

this surprised me though; i expected 720 to win out.

the difference between shooting 1080 and uprezzing from 720 is that its better to let the camera handle it because the sensor is somewhere between 720 and 1080. if you upres in post you only have 720 lines of vertical res to work with whereas the camera has more (not a full 1080 though).

additionally, i have come to rely on using the extra space of 1080 footage in a 480 sd project to fake zooms or reframe and other fun effects. with 720 you have a lot less room to work with.

however, if file size is an issue, then recording at 720 should make smaller files and is easier to playback and edit.
 
Agreed with everything Averan said.

One additional consideration is color resolution. It's true that the image won't have as much detail as 1080p can fully store (Panasonic's white paper lists the potential resolution of the chipset at 1440x810, which is a little more than 720p can store, but not as much as 1080p can handle). So the overall resolved luminance detail will be a little higher on 1080p than on 720p (assuming we're talking about 24p here, right?) However, there will be a lot higher color accuracy on the 1080p footage, because while both systems use 4:2:0 color sampling, the higher spatial resolution of the 1080p frame means that more color samples will be stored.

720p = 640 x 360 color samples.
1080p = 960 x 540 color samples. That's 2.25x as much color information.

That should mean overall better-looking, more-accurate image reproduction, and certainly better results for chroma-keying, when using 1080p instead of 720p.
 
Barry_Green said:
Agreed with everything Averan said.

One additional consideration is color resolution. It's true that the image won't have as much detail as 1080p can fully store (Panasonic's white paper lists the potential resolution of the chipset at 1440x810, which is a little more than 720p can store, but not as much as 1080p can handle). So the overall resolved luminance detail will be a little higher on 1080p than on 720p (assuming we're talking about 24p here, right?) However, there will be a lot higher color accuracy on the 1080p footage, because while both systems use 4:2:0 color sampling, the higher spatial resolution of the 1080p frame means that more color samples will be stored.

720p = 640 x 360 color samples.
1080p = 960 x 540 color samples. That's 2.25x as much color information.

That should mean overall better-looking, more-accurate image reproduction, and certainly better results for chroma-keying, when using 1080p instead of 720p.
Click to expand...

thanks for breaking that down and explaining that.
As Averan said, I also shoot 1080 and edit on smaller frame timelines 720/sd etc for the same reasons, now this gives me even more reason to shoot 1080.
 
Of course the downside to shooting 1080p on the HMC150 is you cannot do 60fps. You'll have to pick your battles. 1080p for greenscreen/color correction work, and 720p 60 for slow mo.
 
Barry_Green said:
Agreed with everything Averan said.

One additional consideration is color resolution. It's true that the image won't have as much detail as 1080p can fully store (Panasonic's white paper lists the potential resolution of the chipset at 1440x810, which is a little more than 720p can store, but not as much as 1080p can handle). So the overall resolved luminance detail will be a little higher on 1080p than on 720p (assuming we're talking about 24p here, right?) However, there will be a lot higher color accuracy on the 1080p footage, because while both systems use 4:2:0 color sampling, the higher spatial resolution of the 1080p frame means that more color samples will be stored.

720p = 640 x 360 color samples.
1080p = 960 x 540 color samples. That's 2.25x as much color information.

That should mean overall better-looking, more-accurate image reproduction, and certainly better results for chroma-keying, when using 1080p instead of 720p.
Click to expand...

if you down convert 1080p to 720p wouldnt it downres the colorsamples as well?
like, put in 1080p footage into a 720p comp and downscale to fit comp... wouldnt that change the colorsamples to 640x360??
 
iFilm7 said:
if you down convert 1080p to 720p wouldnt it downres the colorsamples as well?
like, put in 1080p footage into a 720p comp and downscale to fit comp... wouldnt that change the colorsamples to 640x360??
Click to expand...

ooooh! good question. if color samples are limited by spatial resolution, then it makes sense that downrezzing would lose some color info.

but, even if that is true, you'll lose less downrezzing than you would by capturing less up front.

and, i don't think you lose any while editing the 1080 in a 720 project...so fx and stuff should have all that extra info to work with. you'll lose color samples in the final export when the 1080 is actually downrezzed.

that's just my logic trying to deduce what's happening.

in lieu of a knowledgable answer, you could easily test this and post your results for us to see..... ;)
 
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