Six, digital camera color management

Digital camera management is generally used, GretagMacbeth, ColorChecker or GretagMacbeth DC or SG, SG pay more attention to the performance of the skin color. However, digital cameras have to face many natural light sources and have multiple spectral effects. Therefore, metamerism is more serious. For these reasons, digital cameras cannot be as precise as scanners, which involves different light sources. At the bottom, it will shoot different colors, so the digital camera's ICC will change due to changes in the light source.

Seven, Monitor's color management

When you want to do color management on the screen, you must pay attention to the following points. It is most important to determine Luminance of Monitor, set the white point of Monitor, set the tone reproduction curve of Monitor, and set the black color of Monitor.

â—† Clean the screen surface

â—† Warm up for 30 minutes

â—† Ambient light illumination weakens

â—† Determine Luminance for Monitor (foot-lamberts or cd/m2)

â—† Set Monitor White Point (Kevlvins)

â—† Set the tone reproduction curve of Monitor (Gamma)

â—† Set Monitor black (foot-lamberts or cd/m2)

In the case of screen proofing, what is the brightness of the screen, and what is the Luminance, the specification of s RGB is 80 cd/m2, such as 80 cd/m2 will be a little darker, in fact, according to the environment, The trial height was increased to 85 cd/m2 to 95 cd/m2. If it is a liquid crystal screen, it may need to be adjusted brighter. Again, the decision to white point is actually the color temperature and the characteristic curve of Gamma. Finally, there is a black setting for the Moniter, which is at the level of the darkness. When toning, black must be turned on and lightened black so that it can be represented on the dark side. However, if you want to turn dark on the LCD screen, you can't do it because the light of the LCD screen will always light up. , so if you want to lighten the black lighter it is more unlikely, because the LCD screen does not represent the strength of light and the strength of light as the CRT screen, so the two will be quite different.

â—† The first C of the color management (Calibration correction)

When the brightness (brightnee) and contrast (contrast) settings are made, the adjustment of the brightness is actually adjusted to black, so the black can be adjusted to black to show the black level. If the brightness is 50% in the middle, adjusting the contrast is to adjust the intensity of white, that is, white brightness, intensity can be adjusted, so when you adjust the contrast you can strengthen the intensity. When measuring 80 cd/m2, it is actually adjusting the contrast. The contrast can not be adjusted to the required illuminance. If the situation is poor, it may be necessary to change the screen. That is to introduce a correction program Spyder Pro correction method, adjust the display's gain control to make RGB three colors equal, and the brightness to be adjusted in the range of 85-95 cd/m2, the error value is adjusted to less than 0.5 and can be completed. In addition, the coordinates will be displayed. The general setting is the color temperature of 6500. Here is the coordinates of it. So it is possible to measure RGB three colors, and then RGB is to do a standard distribution, which will be made of RGB three colors. The standard white, what we want is a coordinate axis.

â—† The second C (characterization characterization) of color management

There are adjustments (white on the screen), brightness adjustment (black on screen), setting of monitor type: CRTorLCD, setting of Gamma=2.2 (PC, sRGB), setting of Gamma=1.8 (MAC), setting of standard color temperature 6500k ( sRGB). When adjusting Gamma's replication curve is set to 2.2 used by the PC or 1.8 used by the MAC, assuming compliance with RGB standards, the MAC will be adjusted to 2.2, may not be applicable; because APPLE was originally developed to go to proofread black and white Laser printers, so copy the curve is to use 1.8, so he also adjusted the screen to 1.8, but now both black and white have used color laser printers, so it is recommended that the MAC Gamma is also adjusted to 2.2. After the above settings, the ICC can be generated. The Gamma's convergence means that RGB is 0 to 255, and the Spyder is divided into nine tones. The RGB color curve is modified to a standard gray, for example, the Gamma value is 2.2. To correct Gamma's characteristics at every 30th coordinate, to make a Gamma's characteristic curve, put the screen on each RGB different point and trim it into a Gamma curve. After the correction, there are three kinds of RGB respectively. With different curves, you can generate an ICC profile.

On the LCD side, the LCD does not have a Gamma feature, so it needs to be simulated. Why isn't there Gamma's characteristics, because its lamp is always lit, so Gamma's characteristics are obtained by the light intensity; so it is necessary Use liquid crystal polarization to simulate the Gamma color characteristics of the LCDD. Therefore, the time spent in the Gamma color characteristics of the LCD is longer than that of the CRT. The reason is that the CRT measures nine gray-scale curves, but in the LCD, nine colors of the three colors of RGB are measured. Curve, so the measured data will be a little more.

â—† The third C of the color management (Conversion color conversion)

Color conversion refers to the comparison of color gamuts. If you compare the color gamut of Adobe 1998 with the color gamut of the Viewsonic G90f screen, there is no way to completely cover the color gamut of Adobe 1998. In addition, the accuracy of the color on the screen is worse than that of a printer, and it is a light. When the color is compared with the actual object, the error is often caused by the condition and the like. Therefore, the screen needs to be calibrated once. Normally, if the CRT is used, it is usually calibrated every week. Once, calibrated at least once a month; while LCDs are generally calibrated once a week, but because LCDs use dyes (dye to display color, longer life than CRT, can be calibrated longer.

VIII. Matchprint Virtual Proofing System

This is a very accurate Virtual Proofing System developed by KPG. The error can be within ΔE1. ​​Of course, the screen and printed matter must be checked in a standard observation environment. The proofreading method is to comply with a standard of the ICC. In addition, the most important thing to do in a very strict environment is to make the remote screen, local screen, proofing, or printed matter consistent. The Matching Virtual Proofing System also incorporates RealTime Proof. This RealTime Proof utilizes the technology of image cutting. It is not limited to any file size and type. It can instantly see the required manuscript in the shortest time. With the technology of image cutting, when doing the image cutting technology, you can know the resolution of the user's screen, and then lose the resolution of a screen, so when it is transmitted on the network, it can be used in a short time. It can be seen that even reducing the zooming can immediately see the desired result. This means that when the remote manuscript is drafted, the customer's desired color can be seen directly on the screen. It is not only to provide this technology, but also to provide modifications. For example, this color may not look as accurate as the actual object, and it can be modified immediately with a location that is not color inaccurate, that is to say, at the customer. Between the printing factory and the printing company, the proofreading operation can be done directly on the screen. Therefore, the printing industry has to achieve borderlessness. This is a very easy-to-use system software.

Nine, the color management of the printer

Choosing a good printer (larger color gamut) is half the success. General inkjet and laser printers are RGB color modes, so the purpose of the ICC Profile is RGB color space. The printer controlled by the RIP (Raster Processor) is mostly CMYK mode, so the destination ICC Profile is the color space of CMYK.

(A) The first C of color management (Calibration correction)

The first is to choose whether the quality of the inkjet paper used is good, as well as the cleaning status of the nozzle, the vertical and horizontal alignment, the balance and resolution of the grayscale. After these questions have been completed, it is necessary to calibrate each tone. Each level should be clearly identified. For example, the printer prints a four-color chart to measure with a spectrometer, and then calculates Fix it, so the 50 we want is 50, which is a special function that RIP wants; but if we want to print directly, we can't do calibration and gray balance without going through RIP. (base linearization) action.

(B) The second color management C (Characterization characterization)

Means to measure the color space printed by the printer on the paper, and then read the color through the instrument, although different instruments have different guides, the number of color patches will be different because of the distribution of the instrument Different arrangements but the final result will be the same. The device profile defines the printer's gamut space, such as the print guide (TC918 RGB, 918 color blocks). In fact, characterization means that the printer prints out a guide and uses a spectrometer to read it. Then the color is calculated and a space is put into the RIP to explain the color prediction. Using the ProfileMaker, an ICC profile is generated, and based on the reference data and the measured data, an ICC profile is calculated.

(III) Color Management The Third C (Conversion Color Conversion)

When doing color gamut conversion, each software should set the correct source (input) ICC Profile, such as digital camera, scanner, printer (RGB, CMYK), sRGB, display. Purpose (output) ICC Profile, such as printer (RGB, CMYK), monitor. Rendering Intents: Absolute Colorimetric, Relative Colorimetric, Preceptual, and Saturation.

Source, purpose and color gamut conversion, these are compressed, as long as the compression will lose some of the colors, then how to achieve perfect compression, there is now another new way is to return to the most primitive state, Is to do the color correspondence table. In general, the gamut conversion provided by ICC is the four functions, absolute colorimetric, relative colorimetric, perceptual, and chroma. The gamut conversion is to get the consistent results through the ICC Profile of the screen, the ICC profile of the printer, and the gamut conversion action. This is the job of RIP to do color management. There are two ways for a printer to print a table: one is to print IT8 or more precisely, and the other is to use the ECI2002 guide. The printing machine is also printing the same guide, and then go to the measurement, and then put it into the RIP after the measurement. Color conversion.