Measuring a scanner target
Measuring a scanner target
- Subject: Measuring a scanner target
- From: Marco Ugolini <email@hidden>
- Date: Tue, 9 Oct 2007 13:46:41 -0700 (GMT-07:00)
Brian Lawler wrote:
>If you have an iOne or a SpectroScan you can create a NEW dataset to
>describe the IT8 target.
>
>This is a good idea, since they are photographic paper, and they do
>fade.
>
>The dataset is just a text file read with a spectrophotometer. You
>can use Measure Tool to make a new one that takes into account the
>fading of the original print.
>
>It's not a bad idea to do this with NEW IT8 targets, also, as it will
>measure the ACTUAL color of your target rather than an average of a
>batch.
A very good idea. The mismatch between the data enclosed with the target and the actual ones measured from the scanner target itself can be large enough to "pollute" the profiling process. Unless the target is guaranteed to be highly fade-resistant and stable, measuring it directly is an excellent precaution.
A few precautions, though:
1) Do not "paw" over the scanner target with your hands: always handle it delicately from the edges, and be careful not to scratch it either by rubbing on it with a cloth in an attempt to clean it or by slipping it back into its clear envelope. Even tiny scratches affect the values read by the scanner. The best way that I know of to clean dust off the target is with an air can with short spurts and keeping the can perfectly vertical -- that avoids shooting any of the can's propellant liquid onto the surface.
2) Use the spot measurement tool for the EyeOne Pro when you take the measurements, so that you can center the spectro exactly on each of the patches to be measured (warning: it's a tedious process!). Don't try to measure the patches "by eye" without the spot measurement tool: your measurements will come out wrong. Also, do not drag the spot measuring tool on the target, because you can risk scratching or otherwise damaging it. Make sure that the little "feet" on it have no grit on them.
Marco Ugolini
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