27” imac gaming on lower resolution

Discussion in 'iMac' started by redryder, Jul 27, 2010.

  1. redryder macrumors member

    Mar 7, 2010
    Hi, I assume that the high resolution of the 27” (2560x1440) will make 3D games practically unplayable? I’ve seen posts where people said they game at lower resolutions on the 27”, such as 1920x1200.

    I’m new to imacs, and only have experience on PCs. On a PC LCD, if you run a resolution lower than the native resolution, the result is slightly blurry and loses sharpness. Is that the same with the imac? Or is the sharpness retained but less of the screen is used? How does it work exactly?
  2. REM314 macrumors 6502


    Jun 1, 2009
    No it works the same as you mentioned for a PC.

    You're also right that the GPU in the 27'' iMacs will not be able to play at very high graphics with the native resolution for new games (Crysis (1, warhead, 2), SC2, etc). It will push that GPU to play those games on high graphics even on a slightly lower resolution.
  3. TMRaven macrumors 68020


    Nov 5, 2009
    Difference between maxed out sc2 at 2560x1440 resolution vs maxed out sc2 at 1920x1080 resolution on mobility 4850 is 5-10fps.
  4. /V\acpower macrumors 6502a

    Jul 31, 2007
    Its simple. LCDs have a fixed number of pixels, that number define native resolution.

    If the computer send a signal in a non-native resolution, then the screen still have to show it using its fixed number of physical pixels. So, the screen have to use some kind of algorithm to "create" some new pixels to fill the empty ones, and also since the ratio is not a "natural number" and that you can't divide physical pixels, it even have to change some of the color information of all pixels, just to try to be closer to what the original image represent. Its like i tell you to build a Lego model, and after that i ask you to build the same model but 1.2 time bigger. You will have to change all the structure of your model in order to keep a relatively similar aspect, but it will never be an EXACT copy of the original just 1.2 time bigger. It will look like it but will be just not really as precise as the original.

    Its the same thing for LCD at non-native resolution, that apply to PC and Macs.

    The only exception is if the ratio between native and non-native resolution is a "clean" fraction, like 1/2.

    If i tell you to build a 2 time bigger copy of your lego model, it will be easy. Just double in all dimensions the number of bricks you used. The result will be the "same" as the original, and exactly 2 times bigger.

    So, the 2560x1440 display on the iMac can also render "sharply" a 1280x720 (720p) resolution, since it is exactly half the number of pixels in both dimension. It will just use 4 pixels for every pixels.

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