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【印刷技术】印刷色彩失真的原因及辨别方法(中英对照版)

[Printing technology] The cause of printing color distortion and the discrimination method

At present, there are many sets of color management systems in the printing industry, which have certain control over the color of printing. However, in the current printing customer group, their requirements on color are increasingly demanding. In order to better printing service, it is necessary for us to understand the main factors leading to color distortion and the discrimination method of distortion.

目前，在印刷界已出现很多套色彩管理系统，在印刷的颜色上都有了一定的控制，但是在现在印刷客户群体中，他们对色彩的要求日趋苛刻，为了更好的印刷服务，我们有必要了解导致色彩失真的主要因素以及失真的辨别方法。

One, the main factor that causes color distortion

一、导致色彩失真的主要因素

1. Color reduction causes color distortion

1、色彩还原处理引起色彩失真

Modern printing usually uses C, M, Y, K four color ink reproduction, due to the purity of the ink itself, so printing overprint will also produce color distortion.

现代印刷通常使用C、M、Y、K四色油墨再现色彩，由于油墨本身存在纯度问题，因而印刷叠印时也会产生色彩失真。

2. Color distortion caused by color separation

2、分色处理引起色彩失真

Printing usually uses C, M, Y and K four-color inks to copy colors, while the image information collected by digital acquisition equipment is usually R, G and B information, so before printing and plate making, the image information needs to be converted into C, M, Y and K mode, namely color separation processing. The "color separation" is to decompose the color information of each pixel of the image (generally R, G, B color information) into the color information suitable for printing C, M, Y, K mode. In the process of color separation will cause the loss of color information. In color separation, only according to ink, paper and other printing suitability, the correct setting of color separation parameters (such as setting dot expansion value, gray balance parameters, black plate step adjustment, etc.), it is possible to output high-quality color separation, as far as possible to reduce the loss of color information.

印刷通常使用C、M、Y、K四色油墨复制色彩，而数字采集设备采集到计算机的图像信息通常是R、G、B信息，因而在印刷制版之前需要将图像信息转换成C、M、Y、K模式，即分色处理。所谓“分色”就是将图像每个像素的色彩信息(一般是R、G、B颜色信息)分解转换成适合印刷C、M、Y、K模式的色彩信息。在分色过程中会引起颜色信息丢失。在分色时，只有根据油墨、纸张等印刷适性，正确设置分色参数(如设定网点扩大值、灰平衡参数、黑版阶调等)，才可能输出高质量的分色片，尽可能减少颜色信息的丢失。

3. There is color distortion in the manuscript

3、原稿存在色彩失真

Printed image manuscripts are mostly obtained by means of photography. In addition to color distortion caused by improper operation in the process of shooting, color is reproduced through color materials, which are prone to color decay, and may also cause color distortion in photos. In addition, with the continuous popularization of digital camera, digital image manuscript more and more, and digital camera to the operator's technical requirements greatly improved, because of the operator's technical level, the image is easy to appear dim picture, image blurring and other problems, resulting in the original color distortion.

印刷图像原稿大多是通过摄影手段得到的。对于照片原稿，除了在拍摄过程中由于操作不当造成色彩失真外，由于色彩是通过色料等呈色材料再现的，而呈色材料很容易发生色衰减，因而也可能引起照片色彩的失真。另外，随着数码相机的不断普及，数字图像原稿越来越多，而数码相机对操作人员的技术要求大大提高，由于操作人员的技术水平差，拍摄出来的图像容易出现画面暗淡、图像模糊等问题，造成原稿色彩失真。

4.Color distortion caused by scanning processing

4、扫描处理引起色彩失真

The image density of the photo manuscript is continuous, and the image information needs to be collected into the computer. When scanning an image with a scanning device, the image needs to be segmented into discrete pixel points, and the R, G and B information of each pixel point on the manuscript is collected point by point and line by line. In the process of scanning, the color information of pixels will be lost, and image processing is based on the collected image information, and all color operations are carried out on this basis, without increasing the color information of the image. Therefore, for the photo manuscript, scanning is a very key link in image processing, improper operation will cause image color distortion.

密度是连续的，需要将图像信息采集到计算机中。在利用扫描设备扫描图像时，需要把图像分割成不连续的像素点，逐点逐行采集原稿上每个像素点的R、G、B信息。在扫描过程中，会引起像素点颜色信息的丢失，而图像处理都是以所采集的图像信息为基础，所有关于色彩的操作也都是在此基础上进行，并不能增加图像的颜色信息。因此，对于照片原稿来说，扫描是图像处理中非常关键的一个环节，操作不当就会引起图像色彩失真。

Second, How to distinguish color distortion

二、如何辨别色彩失真

After understanding the main factors of color distortion, how to find color distortion in the actual production process is the key.

对色彩失真的主要因素有了了解后，在实际生产过程中如何发现色彩失真才是关键。

1.First impression reference method

1.第一印象基准法

The human eye has certain adaptability to color. For slightly distorted images of color, repeated observation reduces the ability to recognize. Therefore, when judging whether there is color distortion, it is an important method to use the first impression to eliminate the limitations of human eye color vision.

人的眼睛对色彩具有一定的适应性。对于色彩轻微失真的图像，反复观察会减弱识别的能力。因此，在判断是否存在色彩失真时，利用第一眼的印象来排除人眼颜色视觉的局限性是发现色彩失真的重要方法。

2. Neutral color reference method

2.中性色基准法

There are a lot of neuter color in the life, like black, white, gray, they are the zero point of the color in profusion world, we can serve as the basis point that distinguishes color distortion.

生活中有许多中性色彩，如黑色、白色、灰色等，它们是缤纷世界中颜色的零点，我们可以作为辨别色彩失真的基点。

3. Skin tone reference method

3.肤色基准法

Skin color is the most familiar color for people. All character images, especially those dominated by portraits, can be used as the basis for distinguishing color distortion according to skin color. Whether you have yellow, white or black skin, there is a rule to your skin tone. That is, there is red in yellow, white in red or black in red. If the skin color of the figure in the image is yellow, it will give people a sick feeling. Under normal circumstances, even if the skin color of the figure in the image is yellow, the color correction should be adjusted to the color of blood, that is, yellow with red.

皮肤的颜色是人们最熟悉的色彩，凡是人物图像，尤其是以人物肖像为主的画面，都可以根据皮肤的颜色作为辨别色彩失真的依据。无论黄皮肤、白皮肤或黑皮肤，其肤色都有一个规律，那就是都是血色。即：黄中有红、白里透红或黑中泛红，如果图像中人物肤色偏黄就会给人产生病态的感觉。在正常情况下，即使图像中人物皮肤的颜色真的偏黄，在彩色校正时也要调整为血色，即黄中有红。

In the printing operation, if we master the main factors of distortion and the discrimination method, then we can have a good grasp of the printing color and achieve the complete effect in the customer's mind smoothly. Therefore, the printing color distortion grasp are not ignored by us.

在印刷操作中，对失真的主要因素和辨别方法若熟练掌握，那么在印刷的色彩上就能很好的把握，顺利的达到客户心目中完整的效果。因此，对印刷颜色的失真把握我们是不容忽视的。