NVIDIA's correction

NVIDIA´s correction

In the beginning, everything is deactivated. To benefit from new functions, you have to enter the advanced settings of the graphic card, choose the new type of menu with the icons, and select Video & Television. In the sub-menu, select the option Advanced settings instead of standard (initially selected). Validate the option Adjusting video color settings , then select the last tab, Improvements. Here we go!

Two options both set at 0 are available in this menu: image sharpening and noise reduction.


We took one of our favourite scenes for testing monitors. It is at the beginning of the movie Matrix. Trinity speaks on the phone with Morpheus and the wall on the left of her face is a perfect example of the twinkling effect and imperfections that jump to our eyes. It’s also seen in the color scale of her face, and is a little less perceptible and harder to show in our screenshots. We will focus in this area to illustrate our tests.
The film was displayed on a 20" 4/3 monitor. Screenshots were made in full screen.


We played a little game, selecting several levels of image sharpening and noise reduction factors and captured the results. Here are the consequences for several different adjustments:

Initial settings : correction 0%

0% sharpening; 100% noise

100% sharpening; 0% noise

Choosing extreme values helps to understand the consequences of the adjustments of these parameters and their limits.
By 0% sharpening; 100% noise, we mean that we left the image sharpening to 0 and increased the noise reduction to the maximum. Here the skin depth is non existent. Initially the cheek and forehead had a visible texture. Once the noise correction is activated, they become entirely smooth. There is no noise left in the image and the areas previously subject to twinkling effects are no longer affected. It is impressive, but there are two downsides. The first is that the area is frozen and there are wide plain color areas instead of color scales in motion. This is disturbing and it feels just like if the furniture were not made of enough polygons. Movements become a little bit more approximate and details are lost. Second downside: the reduction also has consequences on the number of colors displayed. The rounded off numbers are not always the best ones as the red colors on the side of the nose and the woman’s lips show. It’s impossible to miss this as she now has a pale face with two big colored spots.

100% sharpening; 0% noise : It is obvious, sharpness is better. The lines of the face are strongly accentuated. It concerns everything including the skin imperfections. Trinity looks 20 years older. The noise on her face is also strongly accentuated.

It is evident that these extreme adjustments won’t do. The good news, however, is that it is possible to find a better compromise. We assume that we can decrease the noise level and improve the sharpness of images. It is all a matter of finding the right adjustment.

0% bord ; 50% bruit

50% bord ; 50% bruit

50% bord ; 0% bruit

Finally, after a couple of trial and errors, we came to the following result:

0% bord ; 0% bruit

20% bord ; 45% bruit

The ambient noise level has noticeably been reduced. On the IPS monitor chosen for this test, it returned to a level comparable to MVA panels. Progress was also visible on the TN monitor with a slight persistent twinkling.

ATI's correction

ATI´s correction

ATI´s procedure is slightly different from NVIDIA’s. The anti-noise function is activated in DVD (SD, MPEG 2) videos since the Catalyst 6.4. Drivers do not give access to the options of sharpening and noise correction. We have to be happy with their choice as it isn´t possible to deactivate it. We compared the quality by changing from the Catalyst 6.3 to the 6.8 (the most recent version).

We tried several monitors and it is slightly better with the latest Catalyst version. You have to focus on the image to see the improvement and right away you may see a couple of rendering differences between ATI and NVIDIA´s movies:

Matrix, ATI
Matrix, NVIDIA

It isn´t because one seems "nicer" than the other that it is more accurate. It is always possible to change the color adjustments for videos. ATI seems to push the extremes a little more than NVIDIA probably by adjusting the gamma.

If we take a closer look, here is the result of ATI´s video with the Catalyst 6.3 (without correction), with the Catalyst 6.8 (with the correction) and of the best results with NVIDIA´s drivers and our personal adjustments:

ATI + Catalyst 6.3

ATI + Catalyst 6.8

NVIDIA

Let´s focus first on ATI´s images. They are at first glance identical. If you take a closer look at the little darker color scale on the cheek, however, you will see that they are softer on the Catalyst 6.8. Color transitions are less abrupt and the image is smoother. In movies, it results in a slightly less visible twinkling effect. Whether we try it with an IPS or TN monitor, videos are nicer with the Catalyst 6.8. With CRT and LCD MVA, the correction doesn´t change the image. The good thing is that at least it doesn´t degrade the already good rendering image.

ATI vs. NVIDIA: NVIDIA´s has a lower contrast. It is softer and has a lower noise level. With ISP and TN monitors, the manual correction is more efficient with the scenes tested than with ATI´s parameters. If the noise in the images bothers you, NVIDIA´s solution is more flexible and will help you to find a better adjustment than ATI’s, which is nevertheless already appreciable.

ATI + Catalyst 6.3

ATI + Catalyst 6.8

We see on this second example that the smoothening is soft with the Catalyst 6.8. It is nevertheless existent and as we see on the cheek some of the colors have been reconstituted. Some of the plain colors areas became much more agreeable color scales, closer to what the image really should be. Once more, it is subtle but it is better than the latest version of drivers.

Conclusion

Conclusion

The correction of the rendering of videos is just at the beginning of its life. We noticed, however, that only the correction of SD sequences like DVDs was activated. The next step will be, as this document provided by NVIDIA shows, to implement it on HD videos:


According to NVIDIA, the correction of HD videos will be less impressive than for SD videos (the correction is activated for all SD sequences: MPEG 2, DivX, QuickTime...). It seems to be a logical choice indeed as we start with a much higher level of precision in HD. Nevertheless, even with sequences encoded in 25 Mbits/s, we continue to see the twinkling effect. This implementation will be appreciated.

In a nutshell

It doesn´t often happen, we really like this function. Yes, the correction of the rendering of videos is a good thing and yes it compensates for the downsides of many LCDs that tend to overly accentuate a sequence’s compression imperfections. We also draw your attention to the fact that these imperfections aren´t something that you have to undergo. The encoding quality isn´t the only factor responsible for noise. Those who still have a CRT and the owners of P-MVA 8 ms will also agree with this fact. If the twinkling effect is still present in recent monitors, we will make do with this improvement.

Regarding the ATI vs NVIDIA duel, our preference goes to NVIDIA (here a Point of View GeForce 7800 GT). After a couple of manual adjustments, we ended up with a much more efficient correction than with the ATI (ASUSTEK X1800 XT). We would really like ATI to give us more latitude in the choice of parameters. Let´s hope that this personalisation will be included in a future version of drivers.