Control of CtP Plates after their Development

New types of measuring devices along with measuring control strips have been developed for proper inspection of the quality of offset printing plates.

CtP technology has an amazing ability to measure the strips in digital form and then directly transferring to printing form, while the conventional measuring control strips used conventional methods for the measurement of quality of printing plates. Using this technology we avoid the inter-process steps involved in the conventional process that used to lead to loss of quality of tonal values during the processing and manufacturing of printing plates. Just because of this the new digital metering control strips are more useful for controlling the process of development of printing plates. The usage of these meters helps us control the intensity of laser operation, fidelity of reproduction raster tonal values, the output resolution of the ready device and many more.

CtP plates have lead to development of more technologies for measuring control strips that are used for control.

The first original solution introduced was Ugra/ FOGRA Digital Plate wedge, it was made for controlling the quality of development of printing plates, this machine served as a standard for the design of other measuring control strips for CtP devices, for example Digi-Control.

In order to check whether the plates are properly lit and developed; measurement and control of the printing form is very crucial to be assessed. All the manufacturers in a venture to maximize the standardization of their measuring devices so that they can solve optimum number of problems such as high contrast, the size of the raster point and determination of the texture on the plates, while a single plate may vary in contrast, tonal surface, the way of screening and their physical characteristics.

Plate Readers are used for measuring devices for measuring the tonal values in the raster on printing plates.

This device, unlike densitometer that operates on the principle of reflected light, digitally records all the details of raster and puts it in a high resolution digital image. This image is later on processed by software that comes along the tool. Using geometrical analysis, this software provides with data on the percentage of coverage of plate with raster dot, on the corner and line screens of conventional raster, dot diameter, and magnified view of raster images.

The new machines are in the pursuit of finding the best contrast between printing and non-printing surfaces independently for the sake of measurement of printing plates.

An additional light source complementary like, white for RGB and IR for UV, aids in choosing the best contrast depending upon the type of printing plate in observation.

Usage of UV and IR light allows the machines to see materials like blurred latent image on the board or bright tones of yellow color on prints.

Mentioning the type of printing plate of the device and method of half-toning is a necessary step for letting the measurement algorithm compensate for specific characteristics. This enables accurate measurement of percentage of dot coverage, especially in areas with problems related to light and dark tones.


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