Terrible image quality after overscan correction.

[perfectska04]

Hi, I just tried the new overscan feature and it seems like an incredible addition - but it produces horrible image quality.

I thought this would finally eliminate my need to use a custom modeline on my LCD TV and allow me to switch from VGA to DVI (as this modeline only works for me over VGA), but it seems as if the display is just shrunk, rather than adjusting the resolution to correct the issue.

The results are similar to shrinking an existing image, so pixels are not truly 1:1 and lines, icons, and text become very blurry and overall display quality goes down significantly when any sort of this correction is enabled.

If I remember correctly, from when I used Windows, the sliders actually modified the resolution (for example, it went from 1280x720 to 1192x672 on the same TV) and image quality was kept intact.

Is this intended, or are there any plans to implement true overscan correction in the future?

Thanks in advance for any help or information regarding this issue.

[Stendall]

LCD and scaling does not mix well.
The only way to look perfect on LCD is using it's native resolution or resolutions that are 2 power of the native.
There are LCD where this effect is less visible, but are LCDs that usually don't have a sharp and crisp image, what is worse.

[perfectska04]

Originally Posted by Stendall

LCD and scaling does not mix well.
The only way to look perfect on LCD is using it's native resolution or resolutions that are 2 power of the native.
There are LCD where this effect is less visible, but are LCDs that usually don't have a sharp and crisp image, what is worse.

I understand where you're coming from. However, using a custom modeline that gives my display a resolution of 1192x672 (or in the past, using the Overscan correction feature in the Windows Nvidia driver) completely eliminated overscan, without any real noticeable image quality degradation. The drawback I encounter is that I can only use said modeline over VGA, as my TV won't accept it over DVI.

My point is that the Linux version of the overscan correction feature is not modifying the display's resolution, but simply shrinking the image down. While this is good in that there are no lost pixels, it produces horrible image quality in comparison to the former method.

The former method is similar to "cropping" the display; the output image still looks sharp, only the effective workspace area is smaller. The method that is currently used is similar to simply shrinking an image; there is no loss of space, but everything looks blurred and crammed together. This is particularly a hindrance for working in icon design, reading normal to small-sized text, and working with lines or vectors. Users who only watch movies or have media front-ends will probably not notice the difference.