QC Testing your Scanner Calibration

Note: This is part of a series of Scanning Guides. Start HERE.

Place a copy of your calibrated .icc profile in the correct location for Photoshop to access.

• Windows: c:\Windows\System32\spool\drivers\color
• macOS: /Library/ColorSync/Profiles

Open the scan of your RAW .tiff image in Photoshop. It should look dark, like this:

In the main Photoshop menu, choose: Edit > Assign Profile > VueScan Device Profile (or whatver you named your Rough Profiler profile). Once applied, it should look similar to this:

Since the bottom left square should be true white, when you eyedrop a few of the random places on it, the eye dropper should lean towards different colors each time (SLIGHTLY). This randomized deviance of hues accounts for a non-bias towards any one particular hue:

If the white square shows no hue bias, you're in good shape. We also need to check the white levels however. To do this properly we need to convert the color space to SRGB first. We'll again go to Edit in Photoshop but this time pick Convert to Profile. We should get a screen that looks like this -







If you used Rough Profiler in Windows your profile is likely an ICM file so  you'll need to change the Engine from Adobe (ACE) to Microsoft ICM. Also make sure the RGB option is set for SRGB. Go ahead and click OK. Now take your eyedropper tool and place it over the bottom right White square of the IT8 card and look at the values in various spot on it.



 

Ideally your RGB values will be in the 240-250 range. Higher than 255 is bad as that means we're losing color information, too much lower than 240 is bad as well as it has the same problem. I recommend trying the VueScan and Rough Profiler methods to see which gets you closer and use that profile for your scans. With my Canon it was the Rough Profiler profile, but it may differ for you.