Color management steps

Color management basically requires three steps. These three steps are abbreviated as "3C", namely "Calibration", "Characterisation" and "Conversion". In Figure 1, the first step is calibration, which means "calibrate the instrument"; the second step is characterisation, which is "establishing characteristics"; and the last is conversion, which means "converting the color space." Whether you choose any developer's color management system, you must go through these three steps sequentially.

The first step in color management - Calibration
Calibration means adjusting the instrument to the standard. All instruments must be calibrated before use to ensure that the instrument behaves properly; for example, a scale or electronic scale. If there is nothing on the scale and the display is not zero, or if the scale is one pound but the display is not a pound, the instrument cannot provide The correct answer, it needs to be repaired or adjusted. Another example is a reflection densitometer, which can measure the density of each ink on four-color prints, showing the relative density of CMYK inks. Usually, each reflection densitometer will have a CMYK density calibration card that is manufactured by the manufacturer. The four colors on the card have been Printed on its standard density. If the reflectance densitometer reads the four colors on the card and the display is different from the number on the card, it means that the instrument needs to be calibrated. Today's densitometers have a function button for the user to calibrate the answer.

The second step of color management - characterisation
The characteristics refer to each colour input device or colour output device, even coloured materials (eg inks, colouring phosphors of the display screen, etc.), having a certain colour gamut or colour performance. ability. The purpose of this step is to establish the range of color representation of the instrument or material and to mathematically record its characteristics for color conversion purposes. Figure 3 shows the color range of a certain instrument and material in terms of CIE xyY. In comparison with the figure, the color range of the human eye is the widest, and the color range of printed matter is the smallest.

The third step of color management - conversion
Conversion refers to the color conversion between instrument and instrument or instrument and material or material and material. Each instrument or material has a different color range. For example, the color display is RGB color, and the color printing is CMYK color (not counting six-color printing or spot color); and the color display of different brands (even the same brand) The range of colors may not be the same, and the color range of the four-color inks of different manufacturers may also be different. Color conversion in color management does not provide 100% of the same color.
Instead, the instrument or material can provide the best color, while allowing users to predict the results. For example, soft proofing utilizes a color display (RGB color) to simulate the color of four-color printing (CMYK color). As shown in Figure 5, the area where the trigon and quadrilateral overlap represents the same color, and the color outside the range is replaced by the color closest to the color management system calculation (gamut mapping). In the same way, we can also use the color simulation of digital scripting to produce the color of prints. See figure 6. Assume that the hexagon represents the color gamut of the six-color digital manuscript. The color range covers four-color printing. Theoretically, it can output the same color as the printed matter. On the contrary, if the four-color printing is to simulate the color of six-color printing, Because some of the six colors exceed their color gamut, the color management system will replace the nearest color calculated by color matching. The color management system can also provide preview (analogue) colors for four-color printing or six-color printing through the display screen; no matter whether the color gamut of the display screen is very wide, it does not affect the color conversion between the instruments. At most it is only an influence. Monitor the authenticity of colors on the monitor.