Color Charts from Canon PowerShot S95 and EOS 20D

J.Beale  Nov. 25 2010

I took photographs of a Gretag-Macbeth ColorChecker and a Wolf Faust IT8.7/2 color chart to measure the color performance of the S95, as compared with the 20D. I shot in both RAW and JPEG formats.  The photos were taken at noon on Nov. 25 2010 on a sunny, cloudless day in Mountain View, CA (coords +37.40, -122.09).  The local sun elevation was 31 degrees, the sun illuminated the chart at an angle of 45 degrees to chart normal vector, and the camera was facing the chart directly at a distance of about 2 meters.  My Sekonic L-508 light meter indicated incident light levels from 15.5 to 15.7 EV during the shots.  

Here is the spectrophotometer data from the ColorChecker chart (and a few measurements on the IT8.7/2): chart-data.xls
The grey card below the chart is a DGC-100 from Robin Myers Imaging ( which I measured to have a reflectance of  35.5% and accurately neutral grey (spectrally flat to 1% from 450-700 nm: DGC-data.xls).

Update 11/28/2010: Dave Coffin provided me with the below line to add to dcraw.c based on  s95_gmb_0068.cr2:
    { "Canon PowerShot S95", 0, 0,
{ 13610,-5487,-1268,-1373,9773,1601,-824,1545,3772 } },

and it works! I made my own dcraw.exe (cygwin, no JPEG, LCMS) and it gives me good looking output from the S95 CR2 files, with colors I think are more accurate than the in-camera JPEG files.
Canon PowerShot S95: Macbeth ColorChecker  (ISO 80)
S95_GMB_0066.CR2  f/4.9, 1/200  (overexp)
S95_GMB_0066.JPG  f/4.9, 1/200
S95_GMB_0067.CR2  f/4.9, 1/400  (about right)
S95_GMB_0067.JPG  f/4.9, 1/400
S95_GMB_0068.CR2  f/4.9, 1/800  (underexp)
S95_GMB_0068.JPG  f/4.9, 1/800
EIXF data from 0067.JPG   EXIF data from 0067.CR2

Canon PowerShot S95: IT8.7/2 chart  (ISO 80)
S95_IT8_0055.CR2  f/4.9, 1/250 (over)
S95_IT8_0055.JPG  f/4.9, 1/250
S95_IT8_0056.CR2  f/4.9, 1/400 (over)
S95_IT8_0056.JPG  f/4.9, 1/400
S95_IT8_0057.CR2  f/4.9, 1/800 (about right)
S95_IT8_0057.JPG  f/4.9, 1/800
S95_IT8_0058.CR2  f/4.9, 1/1600 (dark)
S95_IT8_0058.JPG  f/4.9, 1/1600

Canon EOS 20D: Macbeth ColorChecker  (ISO 100, 24-70 2.8L at 70mm)
20D_GMB_7941.CR2  f/11, 1/50 (over)
20D_GMB_7941.JPG  f/11, 1/50
20D_GMB_7942.CR2  f/11, 1/100 (about right)
20D_GMB_7942.JPG  f/11, 1/100
20D_GMB_7943.CR2  f/11, 1/200 (under)
20D_GMB_7943.JPG  f/11, 1/200

Canon EOS 20D: IT8.7/2 chart  (ISO 100, 24-70 2.8L at 70mm)
20D_IT8_7926.CR2  f/10, 1/60  (over)
20D_IT8_7926.JPG  f/10, 1/60
20D_IT8_7927.CR2  f/10, 1/125  (over)
20D_IT8_7927.JPG  f/10, 1/125
20D_IT8_7928.CR2  f/10, 1/250  (about right)
20D_IT8_7928.JPG  f/10, 1/250
20D_IT8_7929.CR2  f/10, 1/500  (under)
20D_IT8_7929.JPG  f/10, 1/500