1080 vs 720

[fenderjaz]

hi all, 1080,1080, 1080 now this might ruffle a few feathers but ive got a infocus in78 720 res pj and recently seen a few 1080 pjs and too be honest there doesnt seem to be a great deal of difference in terms of pic quality/detail but 1080 is the current flavour of the month so 720 is so very yesterday but i reckon your better off getting a quality 720 pj [ a lot cheaper because its not trendy or now ] anyone else agree? and what about the current hi res audio formats? a quality 5.1 amp/reciever sounds just as good to me.

[Houldey]

I think science can prove that if you sat close enough to a dual screen display, where one screen is showing a 1080p CG film (for argument's sake, as you can't complain that the 'transfer' is poor) and the other the same film, but downscaled to 720p, you could perceive the difference in quality.

That doesn't mean that 720p is rubbish and 1080p is the only way to live, but it is silly to suggest that there is no difference, in my opinion (NB: I don't own any 1080p display devices).

I say, if you're unhappy with 720p quality at your screen size/viewing distance, either reduce/increase it, or move to 1080p. Otherwise just enjoy

[swiftpete]

If you can't afford the latest stuff, don't worry about it, but don't expect a load of av nerds on a forum (I include myself here) to agree that the older stuff is better.

[kbfern]

It is partly true what the OP says in that a good 720p can be as good as a poor 720p.

Image is more than just sharpness,it is also about contrast,colours,motion,shadow detail etc.

However two projectors of similar quality and price the 1080p should always be better.

As far as hd sound is concerned I much prefer the hd variety and you don't need a new amp that does the decoding to get it.

The hd sound will be far better out of a high end amp without decoders but with the bluray player doing the decoding and connected by analog out's from the player than a cheap all singing all dancing £250-£350 new amp.

[dovercat]

Resolution is the least important factor for image quality. Contrast/gamma and Color saturation & accuracy are much more important.

I am even more behind the times than you, I still use an XGA resolution projector with pal dvd player conected via component cables. The projector is darkchip3 and diy modified for a native/simultaneous contrast of >4000:1 in a batcave. The display gamma is around 2.5 for good image depth - apparant contrast. The frequency response (fine detail contrast) is excellent all the way up to 6.75MHz (13.5MHz with progressive scan) the maximum resolution of dvd. Greyscale and color also look good. I am waiting for lcos or led dlp to get cheaper. I would not upgrade just for resolution. I would upgrade for a significatnt 10x increase in simultaneous contrast.

For sound I am still 5.1 and do not use a center speaker. Quality amplification, speakers and room acoustics are most important in my opinion. Along with not living in a flat or terrace or semi, unless you have sound proofing or deaf neighbors. Adding a good quality active subwoofer and some room acoustic treatment made the biggest difference to me. I have read some blu-ray players re-encode to dts 5.1 at maximum bit rate, which is apparantly alot better than just taking the 5.1 mix of the disc. Loss less audio should in theory be a big improvement, but I have no plans to upgrade my sound untill the reciever dies.

Perceived resolution is dependent on the contrast in the fine details, so lens quality (helps determine mtf and chromatic aberration) and display type (helps determine panel alignment and ansi contrast) matter as well as the number of pixels. The resolution of the source is in many ways more important than the resolution of the display as it determines the amount of contrast present in fine details. Post processing also comes into play with detail enhancement on some blu-ray players and frame interpolation on some displays both seeking to improve the perceived resolution. Scaling if source and display do not match also tends to soften the image.

I view visual acuity as coming in three types
Average contrast sensitivity peaks at 3-7 minutes of a degree, details that size are more noticed and determine the perception of sharpness.
Average visual acuity 1 minute of a degree, details that size can still be noticed if you look for them.
Average vermier acuity 1/10 minute of a degree, can still tell the difference between a straight line and a slightly non-straight line.

These are all with a bright high contrast black and white still image and average eyesight. Less bright color moving images are going to lower the eyes/brain ability to notice details, also you see/identify things as objects so on non-objects like test patterns they maybe more visible.

The benefit of higher resolution is being able to use a brighter display or a larger display or a closer viewing distance. If the display stays the same size/distance and brightness you get improved image smoothness.

I think it is more important for displays with poor pixel fill factor due to the screen door effect (the ability to see the grid of lines made up of the gaps between the pixels) which can make images unwatchable. Also displays which use multple panels combined maybe using 1080 panels but due to poor alignment may be producing a combined image with less than 1080 resolution. Their image will be more soft/blurry than it should be for a given resolution. Screen texture can have a similiar effect. As a plus the slightly less focused more blurry pixels will make screendoor and pixilization less noticeable.

Single chip dlp has good pixel fill factor and perfect panel alignment since it only uses one panel. Dlp does however use temporal and spatial dithering in dark greys this tends to slightly blur fine details near black, since increasing resolution does not increase the displays greyscale bit depth it does not solve this, but might slightly reduce it due to having smaller/more pixels.

Pixel fill factor, if you can not see screen door effect at your normal viewing distance even on bright single color images then that is one reason you do not need to bother with 1080.

Pixilization, displaying a black 45 degree line on a white background does it look like a staircase if it does you can see pixilization. If it looks smooth, another reason not to bother.

Smoothness of the image will be improved with higher resolution, and would be improved going even higher than 1080, but the improvement between 720 to 1080 maybe subtle. It should be most noticeable in large details like textures as it effects the perception of the smoothness of lines.

Matching the source resolution for the most detailed image, is another reason. But most sources do not have 1080 worth of details even if they are 1080 resolution and some discs have digital noise reduction on them to reduce film grain which can in effect lower their detail resolution. The difference between 720 and 1080 is not enough for 1080 to make new details/objects visible, but is enough to make the existing details/objects more in focus - sharper - smoother/less blocky and as I mention under smoothness above this maybe most apparant in large details rather than small ones due to the perception of smoothness of lines.
Chroma/color is encoded with half the horizontal and vertical resolution of the Luma/black&white image and extrapolated upto the Luma resolution. So using a 1080 source with a 720 display still gets you the whole 540 color resolution of the source as would even using a XGA resolution display like mine.

[fenderjaz]

Originally Posted by dovercat

Resolution is the least important factor for image quality. Contrast/gamma and Color saturation & accuracy are much more important.

I am even more behind the times than you, I still use an XGA resolution projector with pal dvd player conected via component cables. The projector is darkchip3 and diy modified for a native/simultaneous contrast of >4000:1 in a batcave. The display gamma is around 2.5 for good image depth - apparant contrast. The frequency response (fine detail contrast) is excellent all the way up to 6.75MHz the maximum resolution of dvd. Greyscale and color also look good. I am waiting for lcos or led dlp to get cheaper. I would not upgrade just for resolution. I would upgrade for a significatnt 10x increase in simultaneous contrast.

For sound I am still 5.1 and do not use a center speaker. Quality amplification, speakers and room acoustics are most important in my opinion. Along with not living in a flat or terrace or semi, unless you have sound proofing or deaf neighbors. Adding a good quality active subwoofer and some room acoustic treatment made the biggest difference to me. I have read some blu-ray players re-encode to dts 5.1 at maximum bit rate, which is apparantly alot better than just taking the 5.1 mix of the disc. Loss less audio should in theory be a big improvement, but I have no plans to upgrade my sound untill the reciever dies.

Perceived resolution is dependent on the contrast in the fine details, so lens quality (helps determine mtf and chromatic aberration) and display type (helps determine panel alignment and ansi contrast) matter as well as the number of pixels. The resolution of the source is in many ways more important than the resolution of the display as it determines the amount of contrast present in fine details. Post processing also comes into play with detail enhancement on some blu-ray players and frame interpolation on some displays both seeking to improve the perceived resolution. Scaling if source and display do not match also tends to soften the image.

I view visual acuity as coming in three types
Average contrast sensitivity peaks at 3-7 minutes of a degree, details that size are more noticed and determine the perception of sharpness.
Average visual acuity 1 minute of a degree, details that size can still be noticed if you look for them.
Average vermier acuity 1/10 minute of a degree, can still tell the difference between a straight line and a slightly non-straight line.

These are all with a bright black and white still image and average eyesight. Less bright color moving images are going to lower the eyes/brain ability to notice details, also you see/identify things as objects so on non-objects like test patterns they maybe more visible.

The benefit of higher resolution is being able to use a brighter display or a larger display or a closer viewing distance. If the display stays the same size/distance and brightness you get improved image smoothness.

I think it is more important for displays with poor pixel fill factor due to the screen door effect which can make images unwatchable. Also displays which use multple panels combined maybe using 1080 panels but due to poor alignment may be producing a combined image with less than 1080 resolution. Their image will be more soft/blurry than it should be for a given resolution.

Single chip dlp has good pixel fill factor and perfect panel alignment since it only uses one panel.

Pixel fill factor, if you can not see screen door effect at your normal viewing distance even on bright single color images then that is one reason you do not need to bother with 1080.

Pixilization, displaying a black 45 degree line on a white background does it look like a staircase if it does you can see pixilization. If it looks smooth, another reason not to bother.

Smoothness of the image will be improved with higher resolution, and would be improved going even higher than 1080, but the improvement between 720 to 1080 maybe subtle. It should be most noticeable in large details like textures as it effects the perception of the smoothness of lines.

Matching the source resolution for the most detailed image, is another reason. But most sources do not have 1080 worth of details even if they are 1080 resolution and some discs have digital noise reduction on them to reduce film grain which can in effect lower their resolution. The difference between 720 and 1080 is not enough for 1080 to make new details/objects visible, but is enough to make the existing details/objects more in focus - sharper - smoother/less blocky and as I mention under smoothness above maybe most apparant in large details rather than small ones due to the perception of smoothness of lines.
Chroma/color is encoded with half the horizontal and vertical resolution of the Luma/black&white image and extrapolated upto the Luma resolution. So using a 1080 source with a 720 display still gets you the whole 540 color resolution of the source as would even using a XGA resolution display like mine.

very detailed reply i purchased my infocus in78 [ dark chip3 ] for 870 pounds list price was 2000 pounds [ reviewers agreed that it produces a pic that wouldnt shame a pj costing twice as much ] point being that if someone cant afford a 2 to 3000 pound 1080 pj i think they are far better off going for a very good 720 at half the price rather than getting caught up in the must have 1080 thing. i was going to go for a 1500 pound or so 1080 but im glad now that i didnt having seen what 1500 pounds gets you in the 1080 dept.

[dovercat]

With an old xga lcd projector or dlp svga projector the projectors resolution due to screendoor effect and pixilization dictated the viewing distance. With modern projectors this is not usually the case, so it is an expensive upgrade just to get a slightly smoother looking image.

Still some people have better visual acuity than others or a more critical appraisal of image quality. Higher resolution all other things being equal should look better, even going higher than 1080.

But a old AVS thread "1080p-720p shoot-out in Athens!" points to the fact than even at 1.35xscreen width viewing distance 35 AV enthusiasts thought the difference was minimal to insignificant, some could not tell the difference and a few even thought the 720 projector was the 1080 projector.

http://www.avsforum.com/avs-vb/showt...ight=1080+720+