Among the peculiarities of the PrintVISION print control system, it is worth mentioning the various possibilities of enabling some highly performing correction functions on print defects, such as:
- Enabling correction of vignetting print defects (Vignetting).
Vignetting is represented by a natural reduction in brightness at the edges of the image, typically due to optics (especially at larger views) and / or uneven lighting.
- Enabling correction of printing defects of chromatic aberrations (Cromathic).
Chromatic aberrations consist in a generally radial displacement of the three main colors (R, G, B) due to different wavelengths and are generated by defects in the optics, especially in the case of using additional optical components necessary to frame small areas of the image
- Enabling correction of printing defects of geometric distortions (Distortion).
The geometric distortion is typically produced by optics, especially of the zoom type, and can be of two types: "Barrel" distortion, the image is inflated in the center, like the surface of a wooden barrel, typically produced at the smallest focal lengths (wider field of view); "Pincushion" distortion, the image is squashed in the center, like when you sit on a pillow, typically produced at longer focal lengths (narrower field of view). Enabling correction of chromatic aberration defects (Cromathic).
The Print Log Control: PrintREGIS is the extension of PrintVISION
For the control and timing of the print register, PrintVISION is also available with the PrintREGIS extension, capable of carrying out register control in real time on the printing machine, with automatic feedback through analogue or digital signals.
PrintREGIS: Description of print register control
Register patterns, such as the following, will be used to perform the print register check.
The feedback with the printing machine takes place by pressing the "START" button, the system detects the position differences and performs the registration of the color planes. This command can be carried out only once, or repeated several times for subsequent refinements, obviously waiting a few seconds each time to give the machine the necessary settling time after the correction; usually two or three attempts are enough to get a good registration.
The pattern is always composed of the following components:
- large dot (10 mm diameter), used as the main reference of the reference pattern; this dot must be drawn in the main color plane taken as a reference;
- secondary reference dot (diameter 5 mm), which must be drawn in the same main color plane as the large dot, is used to precisely define the image scale ratio (remember that the magnification ratio must be adjusted with the ZOOM command , the precision of the register control is not however influenced by modest variations of the magnification, as long as the image of the pattern is always well understood in the image);
- small dots for each color plane (2 mm diameter), including the main color plane; the relative position of the various dots, with respect to the nominal reference position, defines the movements to be carried out for recording.
After detecting the offsets, signals are sent to the machine for repositioning the printing rollers. The spot displacement value is calculated according to the expected positions with reference to the Cartesian plane identified by the main and secondary reference dots; the values of the calculated displacements, for all the rollers, expressed in millimeters, are displayed on the monitor.