'Correction of color data' Dialog

You can call up this dialog with the "Test chart > Correct - Fluorescent whitening" menu.

Check and correct color data

In this dialog, you can correct paper white that is important for certain proofs. You can correct the effect of fluorescent whitening either by automatic paper white correction or by a spectral conversion of the color data.

Note: You can also use these functions in the "Create" main function in "Profile Generation Setup" (see 'Correction of color data' Dialog). It is also possible to match the lightness to proofing. Display this dialog by clicking "Modify" at "Paper white correction".

Check the "Correction of fluorescent whitening effect" function and then select the paper white cor­rection you want.

Click "OK" to confirm your changes and close the dialog.

Click "Cancel" to close the dialog and discard any changes to it.

Correction of fluorescent whitening effect

This function is relevant when papers with fluorescent whitening agents are used (for example, paper for color copiers and ink jets). It affects the proof part of the profile.
Optical whiteners have a fluorescent effect so that the paper is perceived as particularly white although technically speaking it has a bluish color cast. If you make a proof based exactly on the val­ues measured, the result will appear too yellow.

Correction can be in two ways:

•using an automatic paper white correction

•or a spectral conversion of the color data.

Change paper white automatically

This function can automatically reduce the effect of fluorescent whitening agents when the proof part is calculated in the profile.
By default, this function is disabled. When this function is activated, evaluation of the proof with a measuring device may produce different results.

Spectral conversion of color data

Spectral color data must be available for this type of correction. In this procedure, all the measured values are corrected before profile calculation. As a result, this correction affects the entire ICC pro­file (all transformation tables).

Fluorescent whitening causes ultraviolet light that cannot be seen by the human eye to be absorbed and visible blue fluorescent light to be emitted in its place. As a result of this conversion, an observer considers the paper to be whiter. But this impression of white is subjective: In Europe, for example, paper is "absolutely white" if the reflected light has somewhat more bluish portions.

You can set the correction intensity (amount of blue) with the slider:

•The default setting (slider position 5) is the equivalent of the spectral effect of a UV filter.

•As you move the slider towards "max" (slider position 10), the bluish color cast is gradually removed by the correction so that the result seems to be yellowish.

•As you move the slider towards "none" (slider position 0), the correction of blue diminishes. There is no correction of the fluorescent whitening effect when the slider is at "none" (0).