[Radiance-general] Scanner Calibration w/ Macbethcal

[Greg Ward]

Hi Marcus,

It is normal due to gamut issues for some saturated colors to be out  
of gamut.  Even if macbethcal issues a warning about some moderate  
colors being out of gamut, it may not be a serious problem, and you  
should judge based on your results.  If you have access to a  
colorimeter, you could check the RGB values against it with the  
xyz_rgb.cal file in the ray/src/cal/cal directory using icalc or  
rcalc as described in:

     http://radsite.lbl.gov/radiance/digests_html/v2n8_1b.html#COLOR_AND

I hope this helps.
-Greg

> From: "Marcus Jacobs" <marcdevon at hotmail.com>
> Date: August 25, 2005 4:04:37 PM PDT
>
> Dear Group
>
> I have recently attempted to calibrate my scanner using a Macbeth  
> Color Chart in conjunction with Radiance's macbethcal. I have run  
> into some issues with 1-3 of my colors (depending on the scanner  
> settings) being out of gamut from reviewing by debug.pic. What I  
> would like to know is if there is any way to rectify this  
> situation? If not, how concerned should I be with this? I wish to  
> use calibrated colors in order to match some of the paint color  
> swatches that are available at many hardware stores for use in my  
> renderings.  Regarding my scanner, I am using an Epson Perfection  
> 2480. Its a great scanner and therefore I wish not to have to  
> replace it in order to experiment in finding another scanner that  
> will keep the colors within gamut. As far as my scanner settings, I  
> choose no auto exposure (selecting this option too leaves some  
> colors out of gamut) and no color correction. Any thoughts or ideas?
>
> Thanks
>
> Marcus
>