Screen E-Book (.PDF) - MacDermid Autotype

amplitude of the effect in a single direction,the moiré becomes more visible (thecomputer model confirms this). So if youchoose an asymmetric dot shape (to avoidthe tone-jump problems with symmetricdots) it’s a good idea to use the minimumasymmetry that will solve your tone-jumpproblems.Out of interest I show a moiré that seemedto be hard to explain. The printer was sofed up with 15° moiré that he decided toprint CMK at 72 lpi and Y at 55 lpi. This indeedremoved the 15° moiré. But it introducedan even uglier, low frequency moiré.It was a pleasant confirmation of the powerof the computer model that the calculatedmoiré exactly matched what was seen inthe print.Finally, some advanced RIP suppliers offera choice of a 15° with a certain degreeof stochastic content. As you go higher instochastic content the moiré disappears,but to some eyes the print starts to lookuglier. With a good RIP you can get the balanceright, just bringing down the visibilityof the moiré without destroying that comfortinghalftone look in your print.3 – Unstable Rosette MoiréOur beloved rosettes are a form of highfrequency moiré. Because they are highfrequency, we don’t really notice them,indeed we instinctively have a nice warmfeeling about a nice rosette. But there’s anugly side to the rosette. In general, it is anunstable configuration. I’d have to go intosome hairy maths to describe all this, butFigure 9. A moiréas a result oftrying to be tooclever.117