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grayscale displays and human vision

Posted by John Oreopoulos on Jul 06, 2006; 7:01pm
URL: http://imagej.273.s1.nabble.com/grayscale-displays-and-human-vision-tp3702214.html

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