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Digital Print Quality Control
- May 29, 2018 -

The digital printing of our common street digital print shop is usually non-professional, and its products are mostly personalized prints such as business cards, books and magazines, photo albums, desk calendars, greeting cards, promotional pages, and various types of documents. Because the customer does not require high quality printing, the printed product may not be completely faithful to the original document, but only needs to meet the individual requirements. For such prints, the quality of prints is usually checked by subjective feelings, that is, checking the memory colors of images, such as the sky, people's skin color, fruits, grass, etc. This method is not accurate. Professional digital printing, which has a high requirement for printing quality, must be strictly examined in the standard environment from the four aspects of the color, level, clarity and consistency of the image.

When giving students digital printing training courses, I often find that the quality of the same batch of printed products printed by the same digital printing machine is different, even if the same ink and paper are used. Digital printing quality is affected and restricted by many factors. In the digital printing process, it is necessary to take effective measures to effectively control the printing quality of digital printing products.

Preprint design and processing of digital printing products

1. Process the manuscript

The originals provided by customers often have problems such as color shift, insufficient saturation, and poor resolution. If they are not processed, they are directly printed on the machine, and the printing quality is often poor. Therefore, in order to control the quality of digital prints, it is necessary to correct the customer's original color deviation, correct black and white fields, sharpening and other processing. The manuscript is different for different situations.

(1) Overexposure

Excessive exposure, the original image looks white and bright, the entire image contrast is small, saturation is insufficient. Therefore, it is necessary to increase the density of the intermediate tone, enhance image contrast, and enrich the image hierarchy.

(2) Underexposure

Underexposure, the original image looks dark overall, dark tone level is lost. Therefore, it is necessary to enrich the brightness level by reducing the density of the dark tone in the middle tone.

(3) Normal exposure

Some people think that the normal exposure of the original does not need to deal with, in fact, is wrong, the need for normal calibration when processing, do some edge sharpening, enrich the fine level of the image.

2. Carefully select the substrate

Digital printing requires more printing materials. For example, the HP Indigo 5500 Digital Press requires the use of preprocessed paper for printing. There are many types of paper used for digital printing, and workers need to choose the right paper for different products.

3. Correct the monitor regularly

The color gamut of the display is larger than the color gamut of the proofer and the digital printer. Therefore, the phenomenon that the color displayed on the monitor and the printed color are inconsistent often occurs. In order to control the print quality of the digital print and achieve WYSIWYG, it must be periodically Correct the monitor.

4 correct choice of color management file

In pre-press production, we often use software such as Indesign, Photoshop and Illustrator. When performing color conversion, we should pay attention to the correct color management file.

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