Method for scanning screened image master images

A method for pixel-by-pixel and line-by-line opto-electronic scanning of a screened image master with a scanner device wherein before the actual scanning of the master, performing the steps of:

• identifying at least one master area as a screen area containing a screen identified in the screened image master;
• converting image values of the identified screen area of the image master present in a locus domain by a Fourier transformation into a frequency domain as a spatial frequency spectrum;
• identifying screen width and screen angle of the screen of the image master from the spatial frequency spectrum;
• determining scan frequencies from the spatial frequency spectrum that are optimum for a Moiré-free scanning for the identified screen angle and the identified screen width of the screen of the image master;
• setting the optimum scan frequencies that determine scan fineness at the scanner device;
• and
• scanning the screened image master with the set optimum scan frequencies for acquiring image values required for reproduction of the screened image master.

A method for opto-electronic scanning of a screened image master with a scanner device wherein before the actual scanning of the master, performing the steps of:

• identifying at least one master area as a screen area containing a screen identified in the screened image master;
• converting image values of the identified screen area of the image master at a locus by a Fourier transformation into a frequency domain as a spatial frequency spectrum;
• identifying screen width and screen angle of the screen of the image master from the spatial frequency spectrum;
• determining scan frequencies from the spatial frequency spectrum that are substantially optimum for a substantially Moiré-free scanning for the identified screen angle and the identified screen width of the screen of the image master;
• setting the optimum scan frequencies that determine scan fineness at the scanner device;
• and
• scanning the screened image master with the set optimum scan frequencies for acquiring image values required for reproduction of the screened image master.