If Maxtone is allowed to appear in too large a range, this can start to create a noticeable appearance of graininess. In order to control this, you must use Harmony to create highlight compression curves, to limit the appearance of Maxtone to only the first two or three nominal tone areas.
In the example step wedge above, you can see that with Maxtone configured at the size of a 5% dot, or 48 microns, the actual TIFF produced will have Maxtone dot removal up to the 6% tone. The strategy to control this appearance is to compress the highlight tonal range very slightly by creating a Harmony curve that pushes the 3% up to 7%.
Harmony compression curve that pushes 3% to 7%
When you apply this curve in Prinergy or Prinergy Evo, it will limit the appearance of Maxtone to only the first few tonal values.
Step wedge run with compression curve (note that 3% now prints with full AM)
Observation of the very extreme highlight areas, represented by the 0.5% step, shows that the Maxtone dots are becoming very isolated. These isolated dots would probably not resist press impression well and would reproduce as scum dot. It is recommended that these extreme highlight dots be clipped off, by using the Minimum Dot Size setting in the output process template.
The resulting output will have the smallest dots cleaned out.
Setting minimum dot size in process template
Potential scum dots cleared out by minimum dot setting
The technique of using a compression curve to limit Maxtone to only the extreme highlights is generally how Maxtone is implemented by printers. Another variation of this technique uses a traditional bump curve, with Maxtone applied only to feather the very edges of the gradient or shadow transitions. This technique uses the standard AM bump curve for a given line screen, and then turns on Maxtone at the calculated size. This will restrict Maxtone to only the tones that are about 1% and below.
The following figures show the three different strategies.
Figure 5. Gradient with uncompressed Maxtone
Figure 6. Gradient with compression curve
Figure 7. Gradient with bump curve and Maxtone
The primary aim of Maxtone implementation is to avoid having Maxtone appear in too wide an area, as this leads to the chance of it being perceived as grainy.
There are other ways to consider using Maxtone. For example, in gradients that are made up of multiple colors there may be one color that fades to 0% in the middle of a blend. The color that goes to 0% can have Maxtone applied to hide the fade. The other colors may be run out with a process template that uses full AM with a bump curve. The presence of AM screens overprinting this fade helps to smooth the transition.