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High Dynamic Range (HDR) Rendering

Next on our list is HDR rendering. Below you can see two screenshots from Splinter Cell Chaos Theory - the left is without HDR and the right is with HDR. You can see the HDR enabled image is slightly brighter, in some parts of the wall, and there are definitely a difference on the light bulb while the wall on the right side stays perfectly dark. The HDR image has more aliasing than the non HDR image (with 4x AA enabled). Looks like HDR's performance hit is about the same with 4xAA.



By enabling HDR in Serious Sam II, you'll notice much more details and colors when playing the game. Look at the clouds and the ground on the edge of the pathway - you'll definitely see the differences. So, HDR does bring us close to 'cinematic quality' in games and real time rendering in general. Again you'll notice the non HDR image (with 4x AA) has less aliasing than the HDR image on the right. Performance levels are about the same, though it looks like HDR is slightly slower in this game than enabling 4xAA with the GeForce 7800GTX and 7800GT. We'll take a closer look at the numbers later.



Unlike transparency antialiasing (or AA and AF in general), HDR can only be enabled if the application made use of it. With quite a performance drop on the GeForce 6 series, no wonder not many games made use of this effect. Hopefully, this will change in the future, partly due to more widespread use of HDR capable hardware from both ATI and NVIDIA.

Performance

We did lots of testing for this article, since we're using new set of drivers. Unfortunately, not all of them can be shown here, it will make this article too long. So, we limit the results to the our latest graphics benchmarks (F.E.A.R, Quake 4, Serious Sam II, Battlefield 2 and Brothers in Arms). Performance with transparency AA in older games are pretty much the same, whether you chose MSAA or SSAA.

Most of the games feature application controlled anti aliasing and anisotropic filtering, sans Battlefield 2 and Brothers In Arms which only have control over one setting (AA in BF2 and AF in Brothers in Arms). We enable AA and AF in-game when possible, either through the menu or console command. For Battlefield 2, anisotropic filtering was enabled through the driver panel as did AA for Brothers in Arms. Image quality setting is set to High Quality for best image quality. Without further ado, here are the results.

Our test setup
AMD Athlon 64 3500+ socket 939
2 x 256 MB Kingston KVR 3-3-3 PC3200 DDR-SDRAM
MSI K8N NForce 4 SLI motherboard
Maxtor DiamondMaxPlus9 80 GBs Serial ATA 8 MB buffer
ASUS E-616 DVD-ROM
450 watts ATX power supply

Windows XP Professional with Service Pack 2 installed
NVIDIA Forceware 81.95 reference driver
NVIDIA NForce 4 6.66 reference driver
Creative SoundBlaster Live! 24 bit 5.12.1.512 driver.
DirectX 9.0c

The results:

Of course, there's no point of using more than 1024 x 768 with 4xAA in F.E.A.R with a single GeForce 7800GTX or 7800GT. Only pay attention to the 1024 x 768 graph. We can definitely see there's no performance difference between no transparency antialiasing, 4x transparency MSAA and SSAA. Not surprising really, since F.E.A.R made little use of transparent textures, particularly in the performance test.

	GeForce 7800GT
	Default	4x AA 16x AF	Alpha MSAA	Alpha SSAA
<30 fps	0	4	6	5
30-45 fps	0	27	27	27
45-60 fps	2	14	12	13
60-90 fps	29	10	10	10
90-120 fps	15	0	6	0

	GeForce 7800GTX
	Default	4x AA 16x AF	Alpha MSAA	Alpha SSAA
<30 fps	0	2	2	2
30-45 fps	0	19	18	20
45-60 fps	1	20	20	19
60-90 fps	24	10	11	11
90-120 fps	18	4	4	3

These fps progress graph confirms our conclusion. The differences between the three transparency antialiasing settings can be attributed to normal variations between runs. With little use of transparent textures throughout the game, there's no point of enabling transparency antialiasing in this game anyway. So it looks like the best image quality is still with 4x AA.

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