Upscaling and Downscaling #Monitors

[Human Being]

What is upscaling and downscaling resolutions in monitors?I know about native resolution that is The Recommended one which can also be seen via Screen Resolution in windows or it's a resolution that fits the exact size of the display unit.But about these two??
I understand downscaling a little bit (that reducing the resolution rather then native.I don't know I'm correct or not)
Apparently,for upscaling,NO IDEA....

Any suggestions?
Thanks.

 

[tigerg]

Upscaling and downscaling are when you send a signal out of the range of the native resolution. When this happens, the monitor has to perform math on your image to adjust it to the number of pixels your display is at natively.

If you have a 720p image on a 1080p display, it will have to stretch the image to the number of pixels on the higher resolution monitor. This doesn't look good because no monitor has a perfect algorithm for this mathematical calculation. Some are better than others, but by definitiion, unless it is a whole ratio (like 2:1) you will get a bad image.

 

[Human Being]

Upscaling and downscaling are when you send a signal out of the range of the native resolution. When this happens, the monitor has to perform math on your image to adjust it to the number of pixels your display is at natively.

If you have a 720p image on a 1080p display, it will have to stretch the image to the number of pixels on the higher resolution monitor. This doesn't look good because no monitor has a perfect algorithm for this mathematical calculation. Some are better than others, but by definitiion, unless it is a whole ratio (like 2:1) you will get a bad image.

Apparently,what I've understood by your suggestion that casting 720p images on 1080p is downscaling.And strech action performed by monitor is upscaling.Is that correct?

 

[Suzuki@1473780084@1473780163]

No, 720 to 1080 is upscaling. Monitors suck at this, even if the resolution is 1920x1080 to 3840x2560, it just looks horrible. TV's handle scaling a lot better though. It looks horrible because you're losing 1:1 pixel mapping. Doesn't matter what resolution if it's outside native. It will introduce a blur, and small fine details will be lost.

 

[tigerg]

Just think about it this way: do you need to scale the image up to fit a higher resolution screen? If your GPU is outputting 720p, your 1080p monitor will need to convert the image from 720p to 1080p.

When this happens, the image will probably look blurry in places.

 

[Human Being]

No, 720 to 1080 is upscaling. Monitors suck at this, even if the resolution is 1920x1080 to 3840x2560, it just looks horrible. TV's handle scaling a lot better though. It looks horrible because you're losing 1:1 pixel mapping. Doesn't matter what resolution if it's outside native. It will introduce a blur, and small fine details will be lost.

You mean that 1920x1080 is provided by GPU and 3840x2560 is that of monitor's resolution?And what about downscaling?

 

[Suzuki@1473780084@1473780163]

Downscaling (like tigerg said) is the GPU renders a higher resolution, math takes care of the rest so that it fits your native resolution. This will look better than native resolution. But because 720 is smaller than 1080, the display has to guess what pixel (colors) are missing. I've only seen TV's get this somewhat correct, especially expensive models with great scalers.

 

[tigerg]

Downscaling is the opposite, though most monitors don't support this and will give you an "out of range" error.

Downscaling is certainly possible, I wrote software to scale images a while back and the hard part is the algorithm you pick to do your gradient math between pixels that don't exist.

 

[Human Being]

Just think about it this way: do you need to scale the image up to fit a higher resolution screen? If your GPU is outputting 720p, your 1080p monitor will need to convert the image from 720p to 1080p.

When this happens, the image will probably look blurry in places.

Blurry image because of missing pixels?

 

[Suzuki@1473780084@1473780163]

"1:1 pixel mapping is a video display technique applicable to devices with native fixed pixels, such as LCD monitors and plasma displays. A monitor that has been set to 1:1 pixel mapping will display an input source without scaling it, such that each pixel received is mapped to a single native pixel on the monitor. This technique avoids loss of sharpness due to scaling artifacts and normally[a] avoids incorrect aspect ratio due to stretching. If the input resolution is less than the monitor's native resolution, this will result in black borders around the image (e.g. letterboxing or windowboxing)."

-Wikipedia

 

[Human Being]

Downscaling is the opposite, though most monitors don't support this and will give you an "out of range" error.

Downscaling is certainly possible, I wrote software to scale images a while back and the hard part is the algorithm you pick to do your gradient math between pixels that don't exist.

Downscaling is like GPU rendering 1920x1080(maxium resolution) on a 720p monitor or less?

 

[tigerg]

Yes.

If you have 2 pixels (red, blue), how would you make this little image on 3 pixels (red, ??, blue)? Math is used to determine the color of the "??" pixel. Generally speaking, I would say it becomes a purple color.

Or, because color is hard to do, lets say with greyscale:

(black, white) --> (black, grey, white)... but how dark or light of grey? That's what the algorithm will determine.

 

[Human Being]

Yes.

If you have 2 pixels (red, blue), how would you make this little image on 3 pixels (red, ??, blue)? Math is used to determine the color of the "??" pixel. Generally speaking, I would say it becomes a purple color.

So,upscaling causes lose of pixels that makes the image blurry.On the contrary what about pixels in downscaling?Because what I've seen in games while playing that if I reduced resolution let's say to 800x600 rather than full 1080p HD the image looks more crystal clear because of more pixels.Is this downscaling too?

 

[Suzuki@1473780084@1473780163]

800x600 cannot look better than 1920x1080. What?

 

[tigerg]

In upscaling you are creating new pixels. Because you are going up, you have to guess what a new pixel would be. Because the math of this guessing is hard, you will generally come up with a more blurry image.

Downscaling is where you cut out pixels from the image. But which ones do you cut out? And do you change any of the ones you have left? Downscaling can look clearer because you are going from more information to less. When you upscale, you have to create new information, and guessing what that info is can be very hard.

 

[Human Being]

800x600 cannot look better than 1920x1080. What?

I'm talking about the jagged edges (which are then resolved by enabling anti-aliasing at certain level) and the number of frames per second.As both of these are slightly resolved by reducing the resolution.

 

[Suzuki@1473780084@1473780163]

You get less jagged edges when increasing the resolution. If you're playing in 800x600 Windowed it may appear sharper, but much less info than 1080.

 

[Human Being]

Let's collect the info I got from you two guys that:

Upscaling: When GPU max. rendering resolution forexample is at 1920x1080 and it is connected to a monitor of max. 3840x2560 and so GPU has to create new info.(pixels) to cast on the monitor.

Downscaling: When GPU max. rendering resolution forexample is at 1920x1080 and it is connected to a monitor of max 720p and so GPU,itself cuts the slice of required amount of pixels by the monitor.

Are we done here now?

 

[tigerg]

Yes, that is a good summary of what we discussed here.

If you are curious, there is a lot of research on this topic on the internet. Searching for "Image Scaling" will turn up lots of good resources, particularly the wikipedia page on that topic.

 

[Human Being]

Thanks a ton for both of you suzuki and tigerg in solving this miss out for me.