4d. Capturing the Chart: IT8

When scanning the IT8 chart, here is a checklist of things to consider:

1. Adjust the white point of the scanner so that the white patch has an RGB value of about 250. Be absolutely certain that its value is less than 255!
   
   
2. If your scanner control software has curves or other controls, adjust them to strive for these "ideal" values for the grayscale patches:
   
   
   It is not critical that these exact values be achieved, the point is to use them as a guide. If you are capturing more than 8-bits per channel, you do not need to strive for the above values — just capture the raw data.
   
   
3. No matter how you adjust the scanner, make sure that there is a difference in RGB values between neighboring patches on the grayscale. This is more important than achieving the ideal target values shown above.
   
   
4. When scanning your real pictures under these same scanning conditions, you may wish to adjust the scanner white point slightly on an image-by-image basis so that the brightest white object in the image does not saturate.