Spectrophotometer

This is a device which measures the amount of reflective light of each color. It will normally take 32 measurements for each color sample. It gives out either spectra or the machine will transform the spectra data to L*a*b* or XYZ.

To do the transformation, you need to specify transform the spectra data to L*a*b* or XYZ. To do the transformation, you will need to specify the Lighting conditions and the angle of observer.

This should be for the pre-press industry D50 and 2 degrees Observer 1931. For other industries choose D65 10 degrees Observer 1961.

There is available a program to download which works with the Spectrolino and Spectroscan from Macbeth Gretag.

The same program will also work with the DPT41 and DTP51 from X- Rite.

If you have another type of Spectrophotometer, there is a program which will let you manually enter the results of the readings in the form of X Y Z or L*a*b*.

If the spectrophotometer does not have a white coating on the holder which closes on to the target, put a white paper behind the target. When you look at your final target, put a white paper behind the target or look at your final output on a white bench.

Do not read your target when it is laid against a black background output on a white bench.

Do not read your target when it is laid against a black background but cover the black with a white paper.

There are some other devices that may be used such as an Eye-One from Gretag Macbeth. The latter is not technically a spectrophotometer but the profiler program can use the output data. Note, the result will not necessarily be as precise as when using spectrophotometer data to make a profile.

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