Apple's 27" iMac only supports native or 720p video input, no 1080p
Apple's revised 27" iMac introduced this spring debuted a new feature: a Mini DisplayPort video port that worked in both directions, enabling external video sources to output video to the screen. That feature is largely limited to 720p in HDTV applications however.
Excitement about the potential for using the iMac and its large, high quality display as an HDMI HDTV or display for a game console such as the Xbox or PlayStation 3 fizzled after it was revealed that the port only supports DisplayPort input signals, and not the VGA or DVI/HDMI video signals that most external devices use.
This limitation effectively limits the iMac to accepting video input from recent MacBooks or other computers that produce DisplayPort video, which works significantly differently from earlier analog VGA or digital formats such as DVI/HDMI.
That technical chasm can be bridged by a converter box that accepts a DVI/HDMI signal (the two video standards are essentially the same in different packaging), transforms it to DisplayPort signaling, and scales it to the output resolution of the iMac.
A simple physical adapter won't work for video input due to the iMac's DisplayPort-only input limitation; cheap Mini DisplayPort-to-HDMI adapters can only extract the HDMI output signal the iMac generates and pushes through its Mini DisplayPort connector. They do not do any signal translation.
Two products that can do this translation work are the AV360? Mini DisplayPort Converter and Kanex HD, both of which cost $150. However, while those products appear to be capable of generating both 720p and 1080p output, the 27" iMac only accepts 720p video or its native 2560x1440 resolution.
EDID limitation
It appears the 27" iMac could accept 1080p input, and certainly can support display of the video resolution, as it falls well within its 2560x1440 native resolution. A similar problem affects Apple's 24" LED Cinema Display, which has a native 1920x1200 resolution but only supports that resolution via its DisplayPort input; like the 27" iMac, it won't accept a 1080p signal (1920x1080), the common format of higher end HD equipment such as HDMI set top boxes and the PS3, even though it appears it should be able to.
The problem is that Apple's EDID (Extended Display Identification Data) on the iMac and LED Cinema Display doesn't advertise 1080p as an option. EDID is a simple data structure a display sends to output devices that outlines what video formats and settings it knows how to support. Both devices appear capable of 1080p but simply don't advertise that capability in a way that external devices like the AV360 and Kanex HD can take advantage of.
It appears Apple could update the firmware for these displays to enable support of 1080p input, allowing users to input full 1080p video from devices such as the PS3. Users might not notice a major difference, as experts say its hard to see a real difference between 720p and 1080p on screens smaller than 50 inches.
However, some devices are hardwired to only support 1080p, and can't scale their output to support the Cinema Display's slightly higher resolution nor the 27" iMacs much higher resolution, forcing them to downscale to 720p or not work at all (as is the case with the LED Cinema Display, which is really only indended to work with Apple's Mini DisplayPort-equipped MacBooks and modern desktop Macs).
Excitement about the potential for using the iMac and its large, high quality display as an HDMI HDTV or display for a game console such as the Xbox or PlayStation 3 fizzled after it was revealed that the port only supports DisplayPort input signals, and not the VGA or DVI/HDMI video signals that most external devices use.
This limitation effectively limits the iMac to accepting video input from recent MacBooks or other computers that produce DisplayPort video, which works significantly differently from earlier analog VGA or digital formats such as DVI/HDMI.
That technical chasm can be bridged by a converter box that accepts a DVI/HDMI signal (the two video standards are essentially the same in different packaging), transforms it to DisplayPort signaling, and scales it to the output resolution of the iMac.
A simple physical adapter won't work for video input due to the iMac's DisplayPort-only input limitation; cheap Mini DisplayPort-to-HDMI adapters can only extract the HDMI output signal the iMac generates and pushes through its Mini DisplayPort connector. They do not do any signal translation.
Two products that can do this translation work are the AV360? Mini DisplayPort Converter and Kanex HD, both of which cost $150. However, while those products appear to be capable of generating both 720p and 1080p output, the 27" iMac only accepts 720p video or its native 2560x1440 resolution.
EDID limitation
It appears the 27" iMac could accept 1080p input, and certainly can support display of the video resolution, as it falls well within its 2560x1440 native resolution. A similar problem affects Apple's 24" LED Cinema Display, which has a native 1920x1200 resolution but only supports that resolution via its DisplayPort input; like the 27" iMac, it won't accept a 1080p signal (1920x1080), the common format of higher end HD equipment such as HDMI set top boxes and the PS3, even though it appears it should be able to.
The problem is that Apple's EDID (Extended Display Identification Data) on the iMac and LED Cinema Display doesn't advertise 1080p as an option. EDID is a simple data structure a display sends to output devices that outlines what video formats and settings it knows how to support. Both devices appear capable of 1080p but simply don't advertise that capability in a way that external devices like the AV360 and Kanex HD can take advantage of.
It appears Apple could update the firmware for these displays to enable support of 1080p input, allowing users to input full 1080p video from devices such as the PS3. Users might not notice a major difference, as experts say its hard to see a real difference between 720p and 1080p on screens smaller than 50 inches.
However, some devices are hardwired to only support 1080p, and can't scale their output to support the Cinema Display's slightly higher resolution nor the 27" iMacs much higher resolution, forcing them to downscale to 720p or not work at all (as is the case with the LED Cinema Display, which is really only indended to work with Apple's Mini DisplayPort-equipped MacBooks and modern desktop Macs).
Comments
...also slightly inaccurate. Apple didn't build a scaler into the iMac capable of converting 1080p.
but you can have 1080p support with this device...
http://www.atlona.com/ATLONA-HDMI-MI...-SWITCHER.html
basically your adding the scaler apple left out.
The claim misses the other half of the equation which is viewing distance from the screen. The 50"+ requirement is based on normal lounge room viewing distances, not sitting at a desk with a screen no more than 1.5 foot from your eyes.
The formula is known as the Lechner Distance. A calc table is available at
The table lists (for 1080) 37.66 as optimal viewing distance for 24" and 42.37" for 27". Both are beyond the 1.5-2' viewing distance of a iMac or Display on a desk and as such mean you can easily see all the detail. At 27" you can be a metre back and still see 1080p
http://hdguru.com/lechner-distance-t...ng-an-hdtv/21/
That line in this article is incorrect.
I like Apple products...a lot. But I've never really understood the value of an Apple display. I like they they seem to be made from better components than other monitors, but it seems like there is a whole helluva lot of stuff that they don't do.
At first, I thought, well, the trade off is that they are made from such nice materials and offer such a great display. Lately, it seems like the displays aren't even that great.
Can someone please just tell me what most people use an Apple display for? To replace a tv? As a second monitor for design stuff (as if you needed more space if you have a 27" monitor)? This is one of those Apple products that I simply can't get my mind around.
Thanks in advance.
Those are blind experts. I see HUGE difference on 46 inch TV set. If someone cannot see it on high quality monitor with certain angular resolution (proper distance) then he/she must have problems with vision. I would suggest visit with optician.
Yes I can see the difference also on 20 inch monitor. As long as resolution for monitor is even or higher than certain HDTV standard with proper ambient light and good display of colors one should see the difference in details between 720p and 1080p. Otherwise it is like saying that it is hard to hear difference between surround and stereo systems.
So...
I like Apple products...a lot. But I've never really understood the value of an Apple display. I like they they seem to be made from better components than other monitors, but it seems like there is a whole helluva lot of stuff that they don't do.
At first, I thought, well, the trade off is that they are made from such nice materials and offer such a great display. Lately, it seems like the displays aren't even that great.
Can someone please just tell me what most people use an Apple display for? To replace a tv? As a second monitor for design stuff (as if you needed more space if you have a 27" monitor)? This is one of those Apple products that I simply can't get my mind around.
Thanks in advance.
there is a huge price jump when you go to displays that are higher rez than 1080p because they require a lot of extra scaling hardware to work at different resolutions. Also they require dual link DVI. Thats why most consumer 27 inch displays only do 1080p. The iMac uses a very high quality IPS panel at 2560 x 1440.
The advantage of the imac is that it can scale its output with the GPU, therefore it can operate without external scaling hardware, which makes it more compact and energy efficient.
Things get a little more complicated when adding an external input. They can't use the GPU for scaling because your not allowed to pass HDCP through the computer component.
Basically they would have to add a whole separate (and somewhat powerful) scaling processor to upscale to the displays native resolution with any decent level of quality. The reason 720p works is because it's exactly half of the iMac's native display resolution, therefore you can scale simply by doubling the pixels.
720p x 2 = 2560 X 1440, the native resolution of the iMac's display.
You cant do that with 1080p, therefore it doesn't work. Apple want's to keep the cost down and they want the computer to be compact. Adding 1080p would require a lot of extra hardware.
Apple added external input so when the computer is out of date, you can still use the display. It's not really meant for using it as a tv but hey for $300 you can get HDMI 1080p, and for $150 you can add HDMI 720p.
To those who have brought up the issue about 720P v 1080P, thank you. I'm really sick of this "you can't even see the difference in most cases" crap being perpetuated without adequate explanation or context. It is ridiculous to talk about comparing resolutions without even mentioning viewing distance, which is the most important factor along with dot pitch.
Regarding this issue in particular, there is more to it than just not getting to see 1080P sourced material.
Devices that cannot output 720P end up outputting 1080P, when then gets downscaled by the converter to 720P, and then upscaled to 2560x1440. This added conversion surely has to reduce the quality of the image. It would be far better to go straight from 1080P source material all the way to the monitor with no scaling.
I find this article fairly misleading. My MacBook Pro can drive my 27" iMac at any resolution, not just 720P. If my MacBook can do it, then and adapter can do it.
Actually, your MacBook is driving the 27 inch iMac at only it's native resolution. The gpu in your MacBook is simply upscaling the lower resolution image before sending it out via displayport. Adapters have another problem. They must convert with hdcp. Your MacBook doesn't.
The problem is that Apple's EDID (Extended Display Identification Data) on the iMac and LED Cinema Display doesn't advertise 1080p as an option. EDID is a simple data structure a display sends to output devices that outlines what video formats and settings it knows how to support. Both devices appear capable of 1080p but simply don't advertise that capability in a way that external devices like the AV360 and Kanex HD can take advantage of.
Nobody really needs 1080. With that size display, you can't see the difference.You can't even get 1080p at the iTunes store.
I really don't care one bit about 1080-p it is all marketing hype. 720 IS HD.
720p x 2 = 2560 X 1440, the native resolution of the iMac's display.
You cant do that with 1080p, therefore it doesn't work.
Apple was smart to do it that way instead of having 1080p as their native resolution.
I don't think that anybody can really see the supposed difference anyways. Its like those golden ears who used to say they could hear all kinds of differences in stereos when really they all pretty much sound the same.
there is a huge price jump when you go to displays that are higher rez than 1080p because they require a lot of extra scaling hardware to work at different resolutions. Also they require dual link DVI. Thats why most consumer 27 inch displays only do 1080p. The iMac uses a very high quality IPS panel at 2560 x 1440.
The advantage of the imac is that it can scale its output with the GPU, therefore it can operate without external scaling hardware, which makes it more compact and energy efficient.
Things get a little more complicated when adding an external input. They can't use the GPU for scaling because your not allowed to pass HDCP through the computer component.
Basically they would have to add a whole separate (and somewhat powerful) scaling processor to upscale to the displays native resolution with any decent level of quality. The reason 720p works is because it's exactly half of the iMac's native display resolution, therefore you can scale simply by doubling the pixels.
720p x 2 = 2560 X 1440, the native resolution of the iMac's display.
You cant do that with 1080p, therefore it doesn't work. Apple want's to keep the cost down and they want the computer to be compact. Adding 1080p would require a lot of extra hardware.
Apple added external input so when the computer is out of date, you can still use the display. It's not really meant for using it as a tv but hey for $300 you can get HDMI 1080p, and for $150 you can add HDMI 720p.
Thanks. That's helps. I never really used my computer for more than...well, a computer. This makes more sense to me now.
Apple's revised 27" iMac introduced this spring debuted a new feature: a Mini DisplayPort video port that worked in both directions, enabling external video sources to output video to the screen. That feature is largely limited to 720p in HDTV applications however...
Thank you Apple. Another reason for me to stay a little bit happier with my late 2008 aluminium iMac.... which does not accept any video input at all.
:-(
"Users might not notice a major difference, as experts say its hard to see a real difference between 720p and 1080p on screens smaller than 50 inches. "
To those who have brought up the issue about 720P v 1080P, thank you. I'm really sick of this "you can't even see the difference in most cases" crap being perpetuated without adequate explanation or context. It is ridiculous to talk about comparing resolutions without even mentioning viewing distance, which is the most important factor along with dot pitch.
Regarding this issue in particular, there is more to it than just not getting to see 1080P sourced material.
Devices that cannot output 720P end up outputting 1080P, when then gets downscaled by the converter to 720P, and then upscaled to 2560x1440. This added conversion surely has to reduce the quality of the image. It would be far better to go straight from 1080P source material all the way to the monitor with no scaling.
The converter I posted a link to converts 1080p directly. Nothing gets downscaled. The 720p adapters don't upscale either. They output 720p and the iMac simply doubles the pixles.
I discovered this after receiving my iMac27 a couple of months ago... Not a deal breaker for me personally, but the 'game loving' kids weren't so forgiving.
I am confused here how does 1080p affect games at all ?
do we use the xbox as the console and the mac as the screen ??
help me please my kids are killing me
9
Nobody really needs 1080. With that size display, you can't see the difference.You can't even get 1080p at the iTunes store.
I really don't care one bit about 1080-p it is all marketing hype. 720 IS HD.
Because you are one happy Apple fan (and apparently 50y+ wearing strong glasses, because you can't see the difference) and smile when ever they sell you old hardware for high price doesn't mean there aren't other people who can think. 720p is HD Ready.
Because you are one happy Apple fan (and apparently 50y+ wearing strong glasses, because you can't see the difference) and smile when ever they sell you old hardware for high price doesn't mean there aren't other people who can think. 720p is HD Ready.
For one thing, the consoles typically only render 720p and then upscale the content but also, the iMac screen is smaller than a typical HDTV so when you sit at the same distance you would from a TV then you certainly shouldn't notice a difference.
I am confused here how does 1080p affect games at all ?
do we use the xbox as the console and the mac as the screen ??
Yeah, you use the xbox as a console and the Mac as the screen. You can do the same thing with an Elgato adaptor:
http://www.youtube.com/watch?v=XDV7SB-pJ4o
Direct input would have less lag though.
help me please my kids are killing me
I have a small issue with the claim that experts say you can't notice the difference between 720 and 1080 on screens under 50".
The claim misses the other half of the equation which is viewing distance from the screen. The 50"+ requirement is based on normal lounge room viewing distances, not sitting at a desk with a screen no more than 1.5 foot from your eyes.
The formula is known as the Lechner Distance. A calc table is available at
The table lists (for 1080) 37.66 as optimal viewing distance for 24" and 42.37" for 27". Both are beyond the 1.5-2' viewing distance of a iMac or Display on a desk and as such mean you can easily see all the detail. At 27" you can be a metre back and still see 1080p
http://hdguru.com/lechner-distance-t...ng-an-hdtv/21/
That line in this article is incorrect.
That stinks as I got 1080i and of course 720p on my 24-27? From HP with hdmi.
I will say this though, for sitting fairly close on a desk, when I had HD cable hooked up, some channels were 720p, others 1080i and nearly evetytime, the 720p looked better. It was like looking through glass. 1080i seemed grainy. Keep in mind I work in audio, video proffesionally and was even offered a job once by Paul, the owner of Groove Tubes as I had one of his Solo 150 watt amp heads that had a warm, round, glassy sound when used with 1950/60 American coke bottle power section. He came in on a saterday, opened just for me (his wherehouse), they got another head, sounded the same, got another, sounded the same, one more, yup, sounded the same and I explained that it had lost this shimmer so convinceingly, he got one more and sure enough, there it was. All the others had a tiny blown capacitor and that's when he jokingly? offered me the job as I hear and see tgings, others may miss. So I guess 720 is cool. It's just to bad there is no HDMI yet. Booo. LOL. PEACE