Terrible quality video when using TV as an external monitor ....

April 26, 2020 8:28 PM

I was hoping to use this Toshiba TV as a monitor for my 2013 vintage Mac Air, but the video output over HDMI is grainy and fuzzy and noisy. Help?

The laptop recognizes the monitor in settings and tries to apply the default Toshiba profile, and it mirrors what's on the laptop screen, but with such poor resolution that its almost unreadable. It works fine when the video input is over wifi. (Fine for a $150 TV with 720p resolution on a 32" screen.) I'm going from my laptap's Thunderbolt port to the TV's HDMI input. I've tried two different cables with the same result. Any suggestions for what I may be missing? Or do I just need to buy an actual monitor?

posted by RandlePatrickMcMurphy to Computers & Internet (7 answers total)

Best answer: I'm not sure what you mean by fuzzy, a picture might help there. Hdmi is a digital signal so any noisy/grainy issues would definitely be the TV.

The low resolution part makes sense though, as that is a 720p tv, which is 1280x720. That's a very low resolution for a pc monitor and is worse than the display on even a 2013 laptop. It also may be having trouble outputting at a resolution that low, most laptops have no problem outputting to a 1080p TV, but 720p is not a common resolution for computers so it may be weirdly stretched. I don't think you're going to get that looking good for anything other than video watching. Another issue you may have is "over scan" which will cut off the corners of your display, there may be an option to turn that off, although probably not for that kind of TV.
posted by JZig at 8:56 PM on April 26, 2020 [2 favorites]

How far back from you is the TV? The pixels are relatively large with that size screen at that resolution. I used a 720p TV briefly as a monitor and it had to be about four feet back from me to not look bad.
posted by Candleman at 10:36 PM on April 26, 2020

If you can switch your screen resolution to 1280x720 it will probably look much better. In the meanwhile (as a guess) your TV is trying to squeeze the Mac Air's native resolution of 1440x900 into 1280x720 which results in a really really bad-looking image.

FWIW if you change the resolution to 1280x720 chances are your laptop screen will then look a bit wonky (though not nearly as bad as your TV looks now) even as the TV image looks much, much better.
posted by flug at 11:40 PM on April 26, 2020

Best answer: 720p sets were typically 1366x768, and your Toshiba appears to be no different [direct link to pdf].

Digital displays look like shit when scaling computer graphics, feed it a 1:1 signal by changing the output pixel count of the Mac not to 1280x720 but to 1366x768.
posted by Bangaioh at 12:52 AM on April 27, 2020 [3 favorites]

Are there settings in the TV for motion blur or other smoothing that might be on, fuzzing the screen?
posted by nickggully at 6:31 AM on April 27, 2020 [1 favorite]

JZig and nickggully are correct, if I'm not mistaken some TV sets, even if fed a signal in their native resolution, will still apply some sort of picture processing, in which case computer graphics will never look good on the TV no matter what you try on the input side.
posted by Bangaioh at 10:44 AM on April 27, 2020

Have you tried not mirroring to see if any of the other resolutions are more satisfactory? Also, open System Preferences from the Apple menu. Click on "Display" Under the "Display" tab, hold down the option key while you press on the "Scaled" button next to the resolution to show all available screen resolutions for that display.
posted by Mo Nickels at 7:58 AM on April 28, 2020