Say, I have a HP pavilion dm1. Each time I run a game on it, the image is stretched to feel the whole widescreen, forcing me to play with a distorted image.

My father has a HP pavilion dm1. Each time he runs a game on it, the game is displayed with the original ratio, a centered "square" image, with just back margins filling the borders of the widescreen.

It's the same games, the same versions. It's a different laptop (I have a slightly newer model). I am very jealous. They are dfferent attitudes, yet both default. Is there a known way to parameter my newer dm1 laptop so that it would behave like my father's older dm1 ?

That depends on what GPU you have:

For ATI:
In order to take advantage of GPU Scaling:
A digital connection must be used between the graphics card and output display device:
A DVI, HDMI or DisplayPort connection is required
A VGA connection is not supported
The display must be set to a non-native resolution
http://support.amd.com/de/kbarticles...PUScaling.aspx
"Use Centered Timings" is the option you need.

For Nvidia:
Just google for "nvidia scaling options" or "nvidia centered timings".

I think the dm1 has AMD graphics?

Try going into Catalyst Control Center. Check "advanced view" under the Preferences tab. Under "Properties", choose "built in display". Then you can select "full screen" or "centered" mode, the latter of which will have black bars.

The problem is, for some reason these options are greyed out on my computer.

(Sorry for the french screenshot, but, there it is.)

FloKaj already posted all you need to know. The options for GPU scaling are only enabled if the display is set to a non-native resolution.

This is quite unclear to me.

I gather "GPU scaling" means displaying the image in its original ratio, despite of the widescreen. This is not needed when a software (like the windows OS itself) is displayed on a resolution that is fully supported by the laptop and its widescreen (this is how I interpret "native"). In that sense, my computer is always set on a "native resolution". I don't need windows to be rduced to a centered square.

When I run a game, that game isn't made for this laptop's native resolutions. It attempts to display itself in its own 4:3 resolution. It is then either stretched or GPU-scaled. Actually, on my laptop it is not GPU-saled. Because windows is set on a native resolution ? I am supposed to set my desktop on a non-native resolution, in order to have the game's non-native resolutions GPU-scaled ?

On the other laptop (which is certainly set on native resolutions by default), the GPU-scaling kicks in when a game (in non-native) resolution is launched. Am I supposed to manually go switch GPU-scaling on, after a game has changed my screen's resolution ?

What are the exact notions that I fail to grasp ?

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Edit : Narrowing issue to "set on non-native resolution". Aren't there drawbacks in setting the default windows display on non-native resolutions (doesn't it mean they are unsupported, or at least "non-optimal"). Is the logic that I could keep my desktop at artificially sub-optimal display qualities, in order for the screen to adapt to the games I launch ?

Yes, due to the... interesting way Catalyst is programmed, you need to set your desktop to a non-native resolution to be able to change GPU scaling settings. Once you changed them, you can switch back to the native resolution.

OOOOOOH

This i hadn't understood. But yes, indeed ! Contrarily to what I assumed (and what confused me a lot), I don't have to stay in the non-native resolution, for these gpu scaling parameters to stay active. It was just a matter of changing resolution to access too the settings interface, but not to keep them enabled. This changes everything, thanks.

I still have one problem, though. There are three options : "maintain aspect ratio", "scale image to full panel size", "use centered timings". What I wish is "maintain aspect ratio". However it only allows me to select either "scale image to" or "use centered". When I tick "maintain aspect ratio" and "apply", it switches back to "scale image to full panel size".

I still haven't found what prevents me to select the first option. Am investigating, but if the answer is obvious to everybody else....

That's usually my preferred option as well but perhaps your GPU doesn't support it..? =(

As i said, "Use Centered Timings" is the option you need.
Just try it... ;-)

What do you think should be differend ?

You wrote:
"My father has a HP pavilion dm1. Each time he runs a game on it, the game is displayed with the original ratio, a centered "square" image, with just back margins filling the borders of the widescreen."

Thats what you have now with "Use Centered Timings".
Everything else would just mean to stretch the image to match your display size...which looks quite ugly. Some displays handle scaling better then other but a 800x600 game will always look bad at a full-screen 16:9 resolution.

As far as I understand it, Telika wants to use the third option (maintain aspect ratio), but only two of the three options work (stretch to full screen and centered timings).

Actually there is no major difference between "maintain aspect ratio" and "scale image to full panel size" as far as i know.

From what I understand, "centered timings" just keeps the game display at original resolution, centered middle in the screen. "Keep ratio" stretches its size until its top/down borders touch the screen borders, leaving only left and right margins black. "Scale" stretches and distorts the image to fill the screen entirely. I'm aiming at the second solution. Size increased to the maximum without distortion, which means black margins only on the sifdes, not over and over the picture.

"Centered timings" on MoM, for instance, makes it a postcard image middle in the screen, with a lot of unused room above, under, and on the sides of it.