Technology and key points of the hottest tone repr

2022-10-23
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Technology and key points of tone replication (2)

Third, correctly divide the tone range of point% value

correctly divide the gradient range of the point% value, so that it corresponds to the gradient range of the original density, with the setting of the gradient range and the adjustment of the level curve

extreme high light 0%

high light 1-10% middle value 5%

bright tone 10-35% middle value 25% 1/4

middle note 35-65% middle value 50% 1/2

dark tone 65-90% middle value 75% 3/4

deep dark tone 90-99% middle value 95%

Extreme Black 100%

extremely high. Therefore, light and extreme black are called two polar colors in photometry, and they are dot tone ranges in technology.Two limit values of, This is very important for setting the gradient range and color correction. In terms of reproduction technology, we should make full use of the 0-100% dot scale value according to the characteristics of the original and the printing suitability conditions to achieve the best image contrast and color saturation

IV. correctly select and set the white field and black field of the original

the correct white field and black field selection and setting of the original is to reproduce the original 2 Power on of the machine is the key to instigate the light to light up the color and level, because only on the basis of correct and reasonable point selection and setting can the color level be adjusted effectively, otherwise everything is blind

the correct selection and setting of white field and black field is to make full use of the color space of paper whiteness and the maximum density of four-color ink stack according to the characteristics of various types of originals and printing suitability conditions, so as to achieve the maximum printing density contrast and visual light and dark contrast

therefore, in order to ensure that the density range of the printed image is as close as possible to the density range of the original, when the printing suitability conditions allow, the original density range should be set on the maximum record point value contrast of the color separation chip as far as possible when the white field and black field are set for the scanning color separation of the electronic separation and desktop system, so that the contrast of the printed image is as close as possible to the contrast of the original, so that the level of the original can be fully reproduced, Achieve the best density contrast effect of printing

why does the point selection setting of white field and black field so emphasize the corresponding adjustment in the high light and dark density range of the sharp rise in the orders of Chinese plastic extruder enterprises

1. Theoretically speaking. From the reflection of objects, photographic manuscript is a compression process, while printing is a compression process. For example, an original scene with a brightness range of 160:1 is reduced to 120:1 on a flat transparent sheet and 30:1 on a flat print. That is, the brightness range of printed matter is sharply reduced to 3/4 than that of transparent film. Therefore, the white field and black field tone setting should make full use of the maximum brightness range that can be reproduced by the print to make it as close as possible to the density range of the original

2. In terms of printing technology. The brightness range of printed matter is affected by four-color printing. The measurement accuracy is limited by the ratio of the maximum comprehensive density of brush ink of about 1.8 to the minimum density of white paper of about 0.04. Therefore, no matter the illuminant and reflector of any brightness on the printed matter, its light sense will never exceed the whiteness of the paper, which may be the mystery of printing image art

therefore, we must make full use of the whiteness of the paper when selecting and setting the white field, and set the extreme highlight in the image to 0% absolute as far as possible, so as to show the brightness of the highlight of the print, and at the same time, we can take into account the level of high brightness. For black field selection, the darkest part of the image must be set to the maximum value that can be printed according to the printing suitability conditions. At the same time, make full use of the black version, open the dark tone level, strengthen the contrast, so as to show the strength of the dark tone of the printing, which is one of the keys to improve the quality of the printing

3. In terms of chromaticity. In theory, white is 100% reflection of panchromatic light, while black is 100% absorption, but in nature, we can only see relatively white and black. Generally speaking, objects that reflect less than 15% of full-color light show a feeling of white

the blackest substance in nature is black velvet, and the whitest substance is heavy barium oxide

according to the national qb320-82 standard, the whiteness of special coated paper is 87%, the best imported coated paper is 89-90%, and the general coated paper is only 80-855, which limits the high brightness of printed matter

to sum up, the key technology of selecting points and setting points in the white field and black field of scanning color separation lies in how to make full use of the limited color space of the whiteness of the paper and the maximum density of four-color ink superposition according to the characteristics of each original to achieve the maximum printing density contrast, so as to try to ensure that the image can be opened from the brightness to the dark area, and the level differences of bright, medium and dark tones can be seen visually, To meet the visual habits and psychological requirements of the audience

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