Color proofing - an image that serves as a model for reproducing color when replicating printed material. It is one of the important tools for ensuring the quality of color reproduction in printing along with densitometric and colorimetric control.
In a broader sense, a color proof can be called any image that the print customer considers to be a color sample: a print on the printer or the original photograph , even a sample product for the catalog, however, the printer will rarely be able to “get” into the proposed image if the preparation did not take into account the realities printing process: paper and ink used , features of the printing press and prepress.
In the narrow sense of color proofing - a specially prepared image obtained using specialized color proofing equipment. This can be a proofing machine, analog proofing, digital proofing or screen proofing. Each of them has its advantages and disadvantages, but in most cases, digital color proofing is recognized as optimal today.
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Proofing machine
Theoretically, the best way to get a reference image for subsequent printing. This uses real printing forms, real paper and ink. You can control the appearance of moire , as the raster structure of the image is reproduced. However, this method may not take into account the features of various printing machines, temperature and humidity in the printing house. In addition, this is the most expensive method and is justified only for publications with very large runs.
Analog Proofing
It is carried out on special (and very expensive) equipment. The starting materials are color-separated films. At the same time, the CMYK colors are alternately applied to the special carrier. This method also allows you to identify problems with moire, as it reproduces the raster structure. Theoretically, analog color proofing is less flexible than digital. However, in practice, this ensures its greater reliability and stability. .
Analog color proofing fundamentally depends on the skill of a specific person setting it up, the correctness of his actions and the accuracy of devices.
Analog color proofing is divided into “dry” and “wet”.
- "Dry" color proof:
- equipment: laminating machine, exhibiting installation, spelling (heating) rollers;
- Materials: paper - chromalite (base), photosensitive film, toner (pigment) 4 colors (CMYK).
- Wet proofing:
- equipment: laminating machine, exhibiting installation, developing installation, drying;
- Materials: 4-color photosensitive film (base) (CMYK).
Digital proofing
It is produced using printing devices both specially made for this purpose as part of color proof complexes, and using high-quality inkjet printers . Devices such as the Canon iPF PRO or Epson Stylus Pro series printers even produce commercial color proofing systems. The main advantage of such systems is their relatively low price, although they do not provide the print quality necessary for reproducing a raster dot.
The production of digital proofs involves the construction of a profile of the printing process and the profile of the printing device for the manufacture of proofs. To calculate profiles, special software is used (for example, GretagMacbeth or X-Rite ), which analyzes the array of colorimetric measurements of test prints created by spectrophotometers (the most common spectrophotometers of the same companies).
Digital color proofing is the most flexible tool, as it can take into account any printing features of a particular printing industry. The main conditions for its application in this case is the high repeatability of the result on the printing press and the constancy of the result over time.
Screen proofing
In this case, a “picture” on the screen of a computer monitor serves as a sample image. This can be a regular professional calibrated monitor or a specialized commercial system for screen proofing. The main advantage is efficiency and low price for each use. The disadvantage is that psychologically the image on the print (in reflected light) and the self-luminous image on the monitor are perceived by a person differently. To use such systems, the printer must have special skills.