[comp.binaries.ibm.pc.d] 256 Shades of Grey on ATI Wonder

coy@ssc-vax.UUCP (Stephen B Coy) (02/01/90)

In article <7767@sdcsvax.UCSD.Edu>, hartung@amos.ucsd.edu.ling.ucsd.edu (Jeff Hartung) writes:
> Furthermore, many questioned whether
> more than 64 would markedly improve the quality of a greyscale image.  The
> argument goes something like this: While the human visual system is very good
> at discerning the difference between two shades when they are side-by-side
> (due to an inhibition mechanism where the nerves in the retina augment
> differences to sharpen borders) it is not-so-good at discerning differences
> when the shades are separated by some space.  Therefore, 64 shades should be
> adequate.

64 shades of grey is definitely not adequate.  I've been generating
a lot of ray traced images lately and one of the options I have is
to display them as grey scales.  The banding is very evident
especially in areas where the intensity is changing slowly.  The
best solution I've found is to display using high resolutions
(640x480 or 800x600) and add random noise to the image.  Noise
levels of about +-8 seem to work well.

>  --Jeff Hartung--  	
>  Disclaimer: My opinions only, etc., etc., BLAH! BLAH! BLAH!...
>  ARPA - hartung@amos.ucsd.edu          UUCP - ucsd!amos.ucsd.edu!hartung
>  BITNET - hartung%amos.ucsd.edu@sds.sdsc.edu

Stephen Coy
uw-beaver!ssc-vax!coy