image.
Network changes and remedies:
The dot size is one of the factors that determine the printing quality. The process of plate making and offset printing will change the dot. Therefore, the dot enlargement, sharpening, deformation, and ghosting of each process must be strictly controlled. We can use the print control strips and magnifying glass simple tools to monitor the changes in the dot, offset printing phenomenon occurs in the offset printing process, all we need to do is to control the dot gain in the standard range before the printing process. In general, offset film is used to expand the printed dots:
FF: Film size: 20%, 40%, 80%, 100%
FD: Printed dot size: 30%, 55%, 90%, 100% more commonly used dot technology
In order to make the dot gain control within the standard range, two different types of dot gains can be compensated for in the plate making and printing process. The dot gain caused by photoshop to plate making and printing is compensated by different methods.
A: Dot enlargement and compensation measures in the printing process
Using the File/CMYK Setup dialog box settings, optional standard dot gains and custom dot gain curves compensate for dot gain.
Standard dot gain value: Standard dot gain value based on experience based on different paper and ink matching.
Dot gain curves: Density measures the density values ​​of the corresponding color patches, using MD equations to calculate the mesh values ​​and corresponding expansion values, from DotGain
Select Curves from the drop-down menu to specify the dot gain value of up to 13 points. Of course, the expanded value of the dot size at other positions is calculated by the software.
B: Compensate dot gain with transfer function
If the image output device used is improperly calibrated and has not been calibrated, the dot may be reduced or increased when the image is transferred to the film. At this time, the transfer function of Postscript technology can be used to compensate.
step:
(1) Output a C, M, Y, K image of 13 gray blocks with a desired dot size on the planned output device to obtain four color separations.
(2) The dot area ratio of the 13 color patches was measured with a transmission densitometer.
(3) Click the Transfer button in the File/Page setup dialog box to enter the Transfer Function dialog box.
(4) Calculate the required adjustments and enter them into the appropriate boxes.
Regardless of the compensation method, the amount of adjustment is as follows: if the pixel value is 127, 50% of the dots should be output, but the dot matrix machine output 60% of the dot network is expanded by 10%, then the compensation adjustment volume should be 50%-10. %=40%, 40% should be filled in the box, so that the imagesetter will output at the user's desired 50% outlet.