32 or 24 bit as default ?

[Inray]

After months using G400Max and G450 at 1600 x 1200 x 32bit i tried 24 bit with the same resolution and refresh.
I did that because i noticed some flickering and delay while scrolling long web pages.
The truth is that using 24bit color cause faster screen redraws and almost 25% faster 2D in generic desktop applications.
The programs we use in our company are CAD/Draft as well as Office and Corel. Most of these apps use 32bit internal color processing and 24bit onscreen.
Anyway i'd like to know your experiences on 32/24 color difference in speed, quality, refresh rates and possible side effects.

regards

Sakis

PS: OS Windows 2000/sp2 IE55/sp2 - hardware used for tests: P4@1700, 512MB, Asus P4T, G400Max/ G450, 29160scsi, SONY F520 21"

[Greebe]

Don't use 24 bit color depth... it's not hardware accellerated

use 16 or 32 only

[Inray]

Greebe i've read about that but i found 24bit much faster atleast on my computer. 32bit is faster on color reproduction only on lower resolutions (1280, 1024) and/or refresh rates than my current one (1600x1200@>100Hz)

[Wombat]

That doesn't make too much sense. 32bpp is faster. 24bpp is the same amount of color, but isn't as easily addressed. It's done to save memory, but slows operations down due to the increased address calculation. The only way 24bpp would be faster is if you really are using all that memory, and 32bpp causes you to have to fetch data from off the card.

[Randy Simons]

Matrox optimized their core for 16, 24 and 32 bit. On my G200 24 bit IS considerably faster than 32 bit. That 24 is "unaccelerated" is true for 3D but since webbrowsing isn't really a 3D-thing, 24 bit desktop colors is indeed faster than 32 bit.

Unlike most other graphic cards I might add, which don't have an optimized 24-bit core, if it is even possible to use 24 bit..

[rubank]

Wombat: ?

Inray: I don´t really know about the G400MAX here, but with the G200 your observations would have been correct. That card by default had the memory clocked higher in 2D mode (=24 bpp) than in 3D mode (=16 and 32 bpp).

The G200 had 3 different clocks, each represented by settings in bios, and I assume the same could be true regarding G400. (I´ve had a G400 but I simply don´t remeber)

When set to 24 bpp there is no 3D accelleration, but 2D is just fine. If you like the looks just use it, you can change to 16 or 32 bpp on the fly when needed.


rubank

[Greebe]

My mistake... 24 bit isn't accellerated in 3D... 2D it is. Don't have my Max or my G200 installed at the moment... my G450 was sold to Dil... and testing the G5... can't talk about that (nor would it apply

[thop]

sorry to warm up such an old thread. but i recently figured out that at 1600x1200x32bit my 16MB g400 doesnt have enough memory left for overlay. so i set the desktop to 24bit which gives the same image as 32bit anyway (right?).
i dont do ANY 3D with the g400 (not even windowed), i guess watching movies doesnt count as 3D. is it safe then to use 24bit?

[VJ]

Re: 32 or 24 bit as default ?

Well, from a quality point of view: if you are into photoprocessing, there is a noticeable difference between 24 bit and 32 bit (depending on the images; I was using 12 bit Nikon RAW-files in AdobeRGB, and switching to 32 bit really brought out the colours).


Jörg

[Maggi]

Re: Re: 32 or 24 bit as default ?

Originally posted by VJ
Well, from a quality point of view: if you are into photoprocessing, there is a noticeable difference between 24 bit and 32 bit (depending on the images; I was using 12 bit Nikon RAW-files in AdobeRGB, and switching to 32 bit really brought out the colours).


Jörg

that must have been a really odd incident, because on all G-series cards, those additional 8bits are not used for color representation, but rather for alpha transparency in HW, ie. you could make use of "video alpha" in Photoshop's preferences.

[VJ]

Re: Re: Re: 32 or 24 bit as default ?

Originally posted by Maggi
that must have been a really odd incident, because on all G-series cards, those additional 8bits are not used for color representation, but rather for alpha transparency in HW, ie. you could make use of "video alpha" in Photoshop's preferences.

Yes, that is what I thought...
Personally, I also wouldn't believe it if someone told me, but I could really notice the blue of the sky in that picture enhancing. I'll put the image up for download, but it will most likely be tomorrow or after the weekend.
Could it have to do with a different palette-allocation approach ? (e.g. Photoshop altering its own colourmanagement ?)

(The card is a G200 Millenium)


Jörg

[Ribbit]

Maybe VJ was using a Parhelia or something else with 10-bit-component colour. (Oh never mind, he replied while I was typing this....)

Thop, I don't know if you can get an overlay in 24-bit mode (I expect you can, can't be bothered to check), the way to find out would be to run a video player (one which you know uses overlay) in a window, and look for the overlay colour while you drag it around (turn on opaque window movement).

[Maggi]

most likely it is based in Photoshop's color management ...

disable it completely and check again