Re: grayscale displays and human vision

Posted by michael shaffer on Jul 10, 2006; 5:55pm
URL: http://imagej.273.s1.nabble.com/grayscale-displays-and-human-vision-tp3702214p3702223.html

Up until a few years ago, and after many Photoshop users complained they
could actually see banding due to Photoshop compensating for the monitors
factory gamma (~2.5) relative to their preferred working space (e.g., ~1.8),
some expensive monitors together with display cards began offering 10bit
precision.  I don't remember which monitors or display cards, but you can
probably google it.

genuinely  :o)
michael shaffer
SEM/MLA Research Coordinator
    <http://www.mun.ca/creait/maf/>
Inco Innovation Centre
c/o Memorial University
St. John's, NL A1C 5S7

> On Jul 6, 2006, at 2:01 PM, John Oreopoulos wrote:
>
> > Hello,
> >
> > I am new to Image J and I have a very general question about how
> > grayscale images are displayed on a computer monitor.  I
> use a 12-bit
> > monochrome CCD camera to capture fluorescent microscope images and
> > save as .tiff files.  When I open my images in ImageJ, the image is
> > displayed as an 8-bit (0-255) on the monitor.  When I hover over a
> > pixel in the image with the mouse pointer, the 12-bit value
> (0-4095)
> > that was captured by the camera is listed in the ImageJ toolbar.  I
> > looked at the ImageJ documentation and read up a little bit
> on digital
> > displays, and it seems that all standard computer monitors will
> > display grayscale images in 8-bit only.  Why is this so?  Is it
> > because of hardware limitations and costs?  Is it because the human
> > eye can only detect 256 discrete shades of gray?  If this
> is not the
> > case, then is there not some loss of information in the
> visual image
> > when it gets displayed at 8-bit?  Am I losing some of the "true"
> > contrast when I look at my 12-bit images in ImageJ?
> > I did a google search on "12-bit grayscale displays" and found some
> > sites that sell special X-ray and MRI monitors with 12-bit or even
> > 16-bit grayscale resolution.  If these kinds of monitors
> exist, then
> > this means the human eye can infact detect more than 256 shades of
> > gray, correct?
> >
> > Thank you in advance for any replies!
> >
> > John O
> >
> --
> -jeffB (Jeff Brandenburg, Duke Center for In-Vivo Microscopy)
>