Practical Color Management Screen Correction and Twilight Light Source (1)

The development of micro-computers has changed a lot in many traditional industries, and the impact on the design and printing industry we are in has greatly changed.

After more than ten years of development, the technology of tabletop layout design has changed the working model of the design draft table and imposition lamp in the past. Instead, it is faced with the work of computer screens. The computer screen will not only design the structure of the screen, but it will also be colorful. However, many workers who face the screen feel that the colors they watch often have a certain distance from the finished product. There are often illusions. Lost feeling. After all, whether the display on the screen can be reproduced on the press, I believe this is a mystery to many readers. This time I will solve this mystery for everyone.

If you need to use the screen to display colors printed in the future, we need to pay attention to and control the following points:

(a) There are appropriate and stable luminescent lights,

(b) The screen is properly calibrated,

(3) There is an appropriate ICC Profile for printing or writing.

Screen calibration definition

In the past, many people said that the screen calibration is to adjust the screen to look like a printed matter. The general approach is to use a well-written or printed manuscript as a benchmark, and then use some software such as Adobe. The provided Gamma either directly utilizes the adjustment function on the display to achieve similar or the same color as the print. But this is a way of not having an ICC workflow before. This approach can only achieve its own purpose for the draft, or it may not show the same result for every working software. This is mainly because there is no centrally controlled part to unify colors, so Apple developed a system extension called ColorSync several years ago. This is the ability to use the system software's ability to centrally process color, but the central controller needs some information on the color characteristics of different devices. These materials are called ICC Profiles, and the generation of these ICC Profiles requires proper hardware and software to do the job.

The primary job of screen calibration

The screen calibration can be divided into two parts. The first is the control of the environment. Although the screen is a transmissive display, the surface of the screen picture tube can also be affected by ambient light, such as direct sunlight. On the screen, the contrast of the image will be reduced in real time. The reason is that the reflected light from the interior of the picture tube glass makes the black part not produce enough black. If you turn off the interior lights, the contrast on the screen suddenly increases, but I believe that no one likes to work in a dark environment, making workers feel uncomfortable. A better method is to properly control the lighting in the room so that the light cannot directly shine on the tube glass. A very effective method is to add a light-blocking part to the screen (see Figure 1).

Stable and standard lighting

Just said that the proper control of the indoor light makes the contrast of the screen good, but many friends will ignore the lighting of the original. When we control the light can not illuminate the screen, the illumination on both sides of the screen is insufficient. , And the color temperature is not accurate, so it is best to have a stable and standard draft light box. This light box is usually a precision design, generally 5000K color temperature of the international standard, and the light reflection angle will not cause reflection, and the lighting is average.

Color Temperature

The color temperature is used to refer to the degree of light color relative to white to quantify the light color performance of the light source. According to the scientific theory, a standard black body with complete absorption and radiation capability is heated, and the temperature rises gradually. The color of the black body is increased until the light source is close to the light color, which is defined as the correlated color temperature of the light source. Abbreviation color temperature, in absolute K (Kelvin, or Kelvin).

The more bluish the light color, the higher the color temperature; the lower the color temperature if it is red. The light color of the day varies with time; the light color is 40 minutes after sunrise, and the color temperature is 3000K; the snow is white and white at noon, rising to 4800~5800K, and it is about 6500K at noon on cloudy days; the light color is red before sunset. The color temperature dropped to about 2200K again. In the artificial light source to separate tungsten light bulb 2000 ~ 3400K, general beige light tube 2600 ~ 4000K, general white light tube 6000 ~ 8000K, and our design and printing industry requires 5000K standard color light tube. Why do you need standard shades? Because of the 5000K color temperature light source:

(a) in the middle of the visible spectrum,

(b) It is a white light with color balance.

(c) does not emphasize any color,

(d) Internationally recognized standards.

The following four pictures demonstrate the effect of the same manuscript under different color temperature light sources.