Is the 27" iMac's 2560x1440 resolution bad for HD video?

PatriotInvasion

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Original poster
Jul 18, 2010
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I have the new quad 27" iMac and record HD video from cable on it. Since those video resolutions are either 1920x1080 or 1280x720, isn't it degrading the video quality by watching it in full screen?

Yes, the added pixels are great for Mac OS windows and stuff, but isn't the high resolution actually a bit of a negative for watching HD video in full screen because it has to stretch the pixels to fill the screen?:confused:
 

TMRaven

macrumors 68020
Nov 5, 2009
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Yes, but only if you're within 2-3 feet of the screen.

If you're sitting back a good 8-10 feet from it, chances are you won't notice the difference with general hd cable.

It's the same way you can totally get away with 720p cable on a native 1920x1080 resolution tv. For general cable that features lots of gradients and shading, it's not so bad. But for computer like stuff with lots of small-fine text, you'll notice the degradation in quality.
 

leman

macrumors G4
Oct 14, 2008
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2560x1440 has the same aspect ratio as 1920x1080. Basically, provided the upscaler does not mess up completely the image should look very similar to one produced by a hypothetic native 27" 1920x1080. So, it will be a bit washed out but that's not a problem if you watch from a suitable distance.
 

PatriotInvasion

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Jul 18, 2010
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Boston, MA
Yes, but only if you're within 2-3 feet of the screen.

If you're sitting back a good 8-10 feet from it, chances are you won't notice the difference with general hd cable.

It's the same way you can totally get away with 720p cable on a native 1920x1080 resolution tv. For general cable that features lots of gradients and shading, it's not so bad. But for computer like stuff with lots of small-fine text, you'll notice the degradation in quality.
Yea figured that. It's not a big deal and 1080i in full screen on the iMac looks great still. Just wanted to confirm that you are losing something with the discrepancy between the ultra high-res display and the max resolutions of HD video.

I suppose the cool thing of the 2560x1440 resolution as that you could literally have four 720p videos playing at once in native resolution on the screen with zero overlap...haha...:p
 

TMRaven

macrumors 68020
Nov 5, 2009
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well there is the white menu bar at the top.


I'm also not sure as to what onboard image interpolation osx uses for its content, but chances are it's not the highest quality out there. I tend to like spline36 interpolation, it produces higher quality resized content than the usual bicubic does.

http://www.all-in-one.ee/~dersch/interpolator/interpolator.html

That gives a pretty good idea of various pixel interpolators.
 

gnasher729

macrumors P6
Nov 25, 2005
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well there is the white menu bar at the top.


I'm also not sure as to what onboard image interpolation osx uses for its content, but chances are it's not the highest quality out there. I tend to like spline36 interpolation, it produces higher quality resized content than the usual bicubic does.

http://www.all-in-one.ee/~dersch/interpolator/interpolator.html

That gives a pretty good idea of various pixel interpolators.
These tests measure the results of 18 resamplings, all under much more tough circumstances. 1920x1080 to 2560x1440 only requires converting three pixels to four; that is quite simple. The input is likely h.264 which has been filtered just before the final step, plus applying the same color hue to four pixels in a square, and nobody can quite agree what kind of filtering gives the best results. So I seriously don't think that anyone will see any quality difference at all.
 

TMRaven

macrumors 68020
Nov 5, 2009
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Yeah, especially not for the average type of video that is broadcasted for cable, and when viewed from a comfortable distance away.
 

gavstephenson

macrumors member
May 25, 2006
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0
i have the resolution on my iMac set to 1600 x 900.

Yet, I watch movies with resolution of 1920 x 1080. Am i not getting the most out of my movies?

Thank you very much. :)
 

PatriotInvasion

macrumors 68000
Original poster
Jul 18, 2010
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Boston, MA
i have the resolution on my iMac set to 1600 x 900.

Yet, I watch movies with resolution of 1920 x 1080. Am i not getting the most out of my movies?

Thank you very much. :)
Why would you set the resolution to less than the native 2560x1440 (assuming you have the 27" iMac)?
 

djrod

macrumors 65816
Sep 16, 2008
1,011
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Madrid - Spain
i have the resolution on my iMac set to 1600 x 900.

Yet, I watch movies with resolution of 1920 x 1080. Am i not getting the most out of my movies?

Thank you very much. :)
You are not getting the full of your Mac, always use the native resolution when using flat screens
 

gavstephenson

macrumors member
May 25, 2006
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0
Thanks v much, guys

I use 1600 x 900 because my eyes are 5 and a half feet (1.6m) away from the screen and using a larger resolution makes everything too small.

Thank you, your comments much appreciated.

----------

yes, i have 27 inch mac, thanks.
 

jwm2

macrumors regular
Jan 5, 2012
231
0
Make your fonts larger. I would think the loss of resolution would add to your eye strain. Using a larger font or magnifying the screen with the use of the accessibility tools seems like a much better solution. And btw you should find a way to put the monitor closer to your face. I'm about 2.5 ft away from mine, and even that is far imo.
 

gavstephenson

macrumors member
May 25, 2006
55
0
Thanks guys.

You are not getting the full of your Mac, always use the native resolution when using flat screens
Might come over as a silly question, but why? Is it because the native resolution provides crisper, clearer images?

I use 'ctrl' 'scroll up' now and again, but I find it preferable to be able to see the full screen. I've increased my fonts where possible, and the finder window and dock and stuff on the desktop is fine. However, the toolbar is small (can't change it I don't think?). The bookmarks bar in safari is another example.
 

leman

macrumors G4
Oct 14, 2008
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I use 1600 x 900 because my eyes are 5 and a half feet (1.6m) away from the screen and using a larger resolution makes everything too small.


[/COLOR]yes, i have 27 inch mac, thanks.
Sorry, but you are doing it completely wrong...

You are sitting way to far from the monitor... Its a great way to strain your eyesight. Switch to native resolution (this would make text clearer and will also give you more working space) and move to your screen so that you are comfortable with the fonts. Using 1600x900 on that iMac is like buying an expensive sports car for sole reason of delivering puzza.
 

alksion

macrumors 68000
Sep 10, 2010
1,708
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Orange County CA
Like everyone has mentioned, sitting in front of a computer desk, fairly close to my iMac, I can tell. But to be honest, I don't mind so much and if it's worth anything, I do most of my TV/Moive/Recording watching on my flat screen TV.
 
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