Packaging bag printing color distortion is a stumbling block, how to break it?

Currently, many color management systems have emerged in the printing industry, and there is a certain degree of control over the printed colors. However, the current customer groups have increasingly demanding requirements for color. In order to better serve customers, Shunxingyuan Packaging, a professional flexible packaging manufacturer, has specially compiled the main factors leading to color distortion and methods for identifying distortion.

I. Main factors leading to color distortion

1. Color reproduction processing causes color distortion

Modern printing usually uses four-color inks (C, M, Y, K) to reproduce colors. Due to the purity problems of the inks themselves, color distortion can also occur during printing overprinting.

2. Color separation processing causes color distortion

Printing usually uses four-color inks (C, M, Y, K) to reproduce colors, while the image information collected by digital acquisition equipment to the computer is usually R, G, B information. Therefore, before printing plate making, the image information needs to be converted into C, M, Y, K mode, which is color separation processing.

So-called "color separation" is to decompose the color information of each pixel of the image (generally R, G, B color information) into color information suitable for printing C, M, Y, K mode.

Color information loss can occur during color separation.

During color separation, only by correctly setting the color separation parameters (such as setting the dot gain value, gray balance parameters, black plate gradation, etc.) according to the printability of the ink, film, etc., can a high-quality color separation film be output, and the loss of color information can be minimized.

3. The original has color distortion

Most of the printing image originals are obtained through photographic means.

For photographic originals, in addition to color distortion caused by improper operation during shooting, because color is reproduced through colorants and other color-rendering materials, and color-rendering materials are prone to color fading, it may also cause color distortion in photos.

In addition, with the increasing popularity of digital cameras, digital image originals are becoming more and more common, and the technical requirements for operators of digital cameras have greatly increased. Due to the poor technical level of operators, the images taken are prone to problems such as dark images and blurred images, causing color distortion in the originals.

4. Scanning processing causes color distortion

The image density of photographic originals is continuous, and the image information needs to be collected into the computer.

When using a scanning device to scan an image, the image needs to be divided into discontinuous pixels, and the R, G, B information of each pixel on the original is collected point by point and line by line.

During the scanning process, the color information of the pixels will be lost, and image processing is based on the collected image information, and all color operations are performed on this basis, and cannot increase the color information of the image.

Therefore, for photographic originals, scanning is a very crucial link in image processing, and improper operation will cause image color distortion.

II. How to identify color distortion

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

1. First impression benchmark method

The human eye has a certain adaptability to color. For images with slight color distortion, repeated observation will weaken the ability to identify.

Therefore, when judging whether there is color distortion, using the first impression to eliminate the limitations of human eye color vision is an important method to find color distortion.

2. Neutral color benchmark method

There are many neutral colors in life, such as black, white, and gray. They are the zero points of colors in the colorful world, and we can use them as the basis for identifying color distortion.

3. Skin tone benchmark method

Skin color is the most familiar color to people. For any image of people, especially images with portraits as the main subject, the skin color can be used as the basis for identifying color distortion.

Regardless of yellow skin, white skin, or black skin, their skin color has a rule, that is, they are all blood-colored. That is: red in yellow, red in white, or red in black. If the skin color of the characters in the image is yellowish, it will give people a sickly feeling.

Under normal circumstances, even if the skin color of the characters in the image is really yellowish, it should be adjusted to blood color during color correction, that is, red in yellow.

In printing operations, if the main factors and identification methods of distortion are mastered skillfully, then the color of printing can be well grasped, and the complete effect in the customer's mind can be smoothly achieved.

Therefore, we cannot ignore the grasp of color distortion in printing.