6-bit vs 8-bit ... was Re: Question about course grey levels in MaximDL...


Nov 26, 2006

 


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#26827 Nov 26, 2006

hi Jan,



I've done some websurfing and discovered to my surprise that

many modern computer monitors are 6-bit (ie 64 levels) rather than

8-bit (256 levels). This amazes me. I thought they were all 8-bit.

My rather new Dell widescreen LCD monitor (2405FPW) turns out to be a

true 8-bit monitor. Perhaps my older monitor was a 6-bit one (at

least it wasn't a 2-bit old monitor :-)). Here's a list of Dell

monitor specs...



en.wikipedia.org/wiki/Dell_monitors



My previous monitor was a ViewSonic. I haven't tracked down its specs

yet.



So, perhaps Doug has simply programmed MaximDL at the 6-bit level for

speed. Doug: Is that what it is?



Also, I made my own 256 graylevel ramp, pasted it into IrfanView, and

saved in in tif, png, and jpg formats. For the tif and png formats,

IrfanView dropped it down from 8-bit to 6-bit. Same for jpg although

for that one the jpg artifacts further complicate the story. Anyway,

at least MaximDL saves an 8-bit file as an 8-bit file even if it

doesn't display it as such.



--Bob



--Bob

--- In MaxImDL@yahoogroups.com, "Jan Rek" jan.rek@...> wrote:

>

> Bob

>

> They both look to be 8 bit grey scale depth to me. I'm on V4.52.

>

> Jan



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#26829 Nov 26, 2006

Another PS:



The problem wasn't IfranView. The image that I pasted into IrfanView

was generated by Matlab and I now see that Matlab also works at the

6-bit level. So, I went to Photoshop and made a grayscale ramp that

really has 8-bit depth. I saved it as a png file. I loaded the png

file into MaximDL and discovered that Photoshop does give a true 8-bit

ramp but even they are sneaky. They dither the ramp slightly to give

the visual impression of even more than 8-bit depth. So, in MaximDL,

I applied a 3x3 median filter to remove the dither. In that way I

have made a true 8-bit grayscale ramp. I've posted it here...



www.princeton.edu/~rvdb/images/NJP/grayscale.png



If this ramp looks the same to you in MaximDL as in a web browser,

then I would conjecture that you have a 6-bit monitor. If the browser

version looks better, then you have an 8-bit monitor. On my Dell

monitor, the difference is significant.



--Bob



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