Analysis of color scale and its influencing factors in printing process (in)

Color element

Color-coded elements are divided into objective color-coded elements (measured by densitometers or other devices) and subjective color-coded elements (estimated by the human eye), but not all color codes contain all of these elements. The general color scale contains the following contents.

(I) Objective elements

10% Hue/Highlight

High light refers to halftone dots whose dots are between 1% and 20%. They are patches of uniform density. They are printed with cyan, magenta, yellow, and black inks. These values ​​are for visual purposes. The evaluation of the platemaking process is useful because oversensitizing the positive plates can “shrink” or discard these small dots. These blocks can also be used to measure the value of highlight dots when the machine is in operation. Some color standards even contain 3% to 5%. Outlets.

25% tone/quarter tone

These uniform color patches contain a dot value of 25%, and a more accurate quarter-tone range of 20% to 40%. They are commonly printed on cyan, magenta, yellow, and black, sometimes with red, green, and blue. Overprinted and printed, and sometimes printed with three- and four-colour balance elements.

50% color/midtone

These uniform patches contain a dot value of 50% and a more accurate halftone range of 40% to 60%. They are commonly printed on cyan, magenta, yellow, and black, and are sometimes printed with red, green, and blue overprints. There are also three- and four-color gray balance elements available for printing. Midtones are very important for people to evaluate the quality of images.

75% color/three-quarter color

Three-quarters of the tone value is important to ensure that the color is clear and distinct during a particular printing process. For example, printing with 85% chromaticity in newspaper printing does not produce a print contrast because the chromaticity value is usually printed in the field, so a chromaticity value of 65% or 70% is sufficient when printing newspapers. When selecting the colorimetric value for printing the contrast, a critical three-quarter chromaticity value is to be determined which maintains vivid color under good printing conditions and fullness under bad printing conditions.

Shadow

The tone contains a halftone dot with a color value of about 85% or up to 95% and 98% of uniform color patches. This colorimetric value provides a basis for the visual inspection of the platemaking process because overexposed plates fill or block empty areas. These objects can be used to measure in-memory dot duplication in dark areas of the image.

Some color mark manufacturers have piled up highlights and dark spots on a color scale to facilitate rapid detection of extreme halftone dot copying.

Monochrome field

Solid color patches for each printing primaries can be used to measure solid ink density and calculate dot gain and print contrast. Measurements of these color patches can also be used to estimate chromaticity errors and gray balance of the primary colors, which is helpful in determining the characteristics of the printing process.

Bicolor overprint

The two-color overprinting field can be used to measure the accuracy and gray balance of the color shades of the green, red, and blue overprints for trap printing.

Three-color overprint

Three-color overprinting is composed of equal parts of yellow, blue and green dots. It is often used to detect color balance, and it can be printed in a brownish color compared to gray balance color blocks.

Tri-color overlay printing can be used to objectively measure the type of field density printed on the press by three-color printing. The on-site overprinting object also allows for the subjective and objective measurement of the accuracy of the third color overprint on the basis of the previous two colors that have been overprinted.

Four-color black block

The total dot area coverage refers to the total area coverage (TAC). These values ​​are used to evaluate the total density after overprinting. The SW OP stipulates that in the process of color separation, the halftone value of the dark tone portion cannot exceed 300% (Remember: 400% of the field portion in all four-color printing is the maximum value); the color required in the publishing field The mark often includes color blocks with a total area of ​​300%. In general, the combination of tones of this object requires about 79% of cyan, 68% of the product, 68% of yellow, and 85% of black. In contrast, the specification SNAP for Non-HeatAddVrdisin gPrintgg specifies that the total dot area should not exceed 260%. In the shaded area of ​​SNAP, the color separation values ​​of color separation generally range from 70% to 80% of cyan, 70% to 80% of product, 70% to 80% of yellow, and 20% to 50% of black.

The four-color black block can be used to measure the above total dot area. At the same time, it also takes into account the factors that register shifting at this point on the tone curve.

Sometimes, in the specification that the actual image portion also uses the total halftone area, these color patches are also used as the under color removal. In order to obtain this maximum value, the color separation operator often uses a color separation method to reduce the halftone dot value and remove the color halftone dot value from the dark tone printing area without affecting the visual effect of the shadowed region of the image. .

Color balanced hexagon

Color-balanced hexagons developed by Brunnner Systems Inc. are elements used to describe the color balance conversion. The hexagon contains gray balance color patches superimposed with 50% cyan, 41% product, and 41% yellow halftone to indicate the smaller dot gain (including unevenness) of the three printing primaries during color conversion. The effect of the expansion of outlets). The hexagonal shape is measured with a density meter, and after special software processing, the dot enlargement values ​​of the three printing primaries can be displayed separately.

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