Using pre-press platemaking experience for RGB data processing

In recent years, due to the development of digital printing, people have had the impression that the color of printed materials is not as stringent as in the past. From the point of view of the printer, the colors that could have been successfully completed cannot be reproduced. Although there may be reasons for the lower cost of the employer and the technical conditions of the platemaking and printing companies, there is another reason that the printing worker may also pessimistically assume that the problem cannot be solved because of digital technology.

Nowadays, the processing of image data often does not take into account printing-related requirements directly from RGB to CMYK. In order to produce high-quality prints from a professional perspective, it is necessary to construct an RGB data workflow and adopt the CMYK data conversion method that is most suitable for printing requirements.

Past platemaking technology is a technology that needs long-term accumulation. For example, in order to reproduce the bright part of the skin, the Japanese skin takes M15% and Y20%, and the European and American take M20%, and the white light on the eyeball is cut off.

Even though digital technology has been implemented today, it is necessary to make good use of the accumulated technologies and perform correct RGB-CMYK data conversion to achieve high-quality printing requirements.

1.RGB data processing

The so-called RGB data processing refers to the use of RGB data as a prepress worker's data, and the data is converted to meet the CMYK printing data. Specifically include: 1). CMYK conversion operations of RGB data; 2). Calibration operations (digital cameras, displays, output devices, storage media, etc.); 3). Image processing operations (color correction, image synthesis, tone conversion, Image correction, etc.) 4). Color management (prediction of output results based on digital data, etc.), etc.

In order to do RGB processing, photographers, designers, plate-making companies, etc. are required to distinguish their respective responsibilities, and RGB data processing standards are formulated accordingly. It is important to clarify the conversion rules.

Prepress companies should set up departments to inspect incoming RGB digital manuscripts in order to transfer the appropriate data to the next process as required.

2. The necessity of RGB workflow

In order to realize the processing of RGB data, it is necessary to structure the workflow corresponding to RGB image data. Now that the number of RGB originals for digital cameras has increased, it is necessary to meet this demand.

Through the implementation of the RGB workflow, the responsibility and workload of photographers, designers, etc. can be reduced, and the occurrence of quality accidents can be reduced. In addition, the delivery period can be shortened and the cost can be reduced. If the image data is made into a database, in addition to improving the work efficiency, the image data can be used again.

3. Benchmarking of RGB Workflow

In order to construct an RGB workflow, it is necessary to provide the cooperation of the employer of the manuscript. Therefore, it is important to propose a standard. The following are specific examples.

1). Requirements for photographers

● Use photoshop 6.0 or later ● Display calibration must be performed ● Do not convert RGB image data to CMYK data ● If you need to make major changes to the color, please send it to prepress company in RAW data format ● Analyze the image The degree is set to 350dpi
● Provide data content records (photographer, use software, color space, resolution, sharpening, etc.)
● When the print size is A4 size, a camera with an image size of 6 million or more is used for photography. ● For print products with high quality requirements such as skin photography, camera photography with an image size of 12 million or more is required.

2). Requirements for designers

● The monitor must be calibrated ● Do not convert RGB image data into CMYK data ● Color correction and color management of the image are sent to the prepress company ● The layout of the continuous spelling, layout, etc. is sent to the prepress company

4. Professional perspective of CMYK conversion

For CMYK conversion, the color settings made according to the graphic must be changed. The conversion job itself is very simple and originally meant to "reproduce the desired color, how to convert to obtain high quality", but this is a professional technical problem. In order to reproduce the colors approaching the RGB image, density adjustment and gradation adjustment are required, and techniques are applied in the CMYK color space to obtain the desired color. Examples of points for obtaining high-quality color reproduction are as follows: 1. At the same time as adjusting the generation of the black edition, a conversion operation is made (making it possible to print clear black text, adjust the balance of gray, approach the original color, and pursue details; etc.); Because the problem of inaccurate printing plates sometimes occurs, trapping is performed (making the background less visible). Where the image data or background in the second point has a hierarchy, it is quite difficult to prevent inaccurate printing plates and requires skilled techniques. This kind of work can be said to be a professional job.