Users who have used inkjet printers, especially those who use general-use consumables, will notice that if they take care, they will find that the colors printed on the photos are different from the colors displayed on the monitor. For example, red is not red enough. The blue color is purple, the color is not bright enough, or the transition between colors is not good. The reason is that besides the reason that the display color correction is wrong, the reason for the ink itself (for example, the use of a compatible ink cartridge with a poor quality, etc.) may also be due to an error in the printer and the ink. But why does the printer have such errors? What is the principle of inkjet printer printing? How to test the error of the printer and ink, and how to properly adjust and improve the printing color according to the error of the printer and the ink, so as to achieve the best printing effect? With this series of questions, the following article discusses and explains.

First, why do the printed photos have color errors?

Products such as color printers and scanners, and their features will all involve a problem of color accuracy, and this problem often dictates important indicators such as the quality of the generated images, the level of product performance, and the ratio of error rates. Color accuracy refers to the proximity of the printer output or scanner input color to the standard color.

RGB mode

We know that in the display, scanners, printers and other products, the commonly used color description and implementation methods of RGB, CMY, and HSB are used to achieve the purpose of accurate output and color input. Among them, RGB refers to the use of red R, green G, blue B combination of three colors to emit light of different colors, displays, projectors and other devices to light the principle and the principle of computer color data storage, is based on this color description method Realized (in the computer, the color of each point on the image generally needs to be stored using a 24-bit RGB information, where 8 bits represent red, 8 bits represent green, and 8 bits represent blue).

CMYK mode

CMY refers to the combination of three basic color materials: cyan C, red M, and yellow Y. People tend to add black K (blacK) pigments to enhance the effect of absorbing pigments. The current popular CMYK mode is formed, so color printers are usually based on these four colors of ink cartridges (some portable printers, due to volume restrictions, will also use CMY's three colors; six or more color printers are increased by Red, light blue and other colors, in order to make the print color transition more natural, improve the printing effect), it is also a color description method used in inkjet printers, prints, and daily use of color painting.

It can be seen that, due to the differences in the principle of the three primary colors of light and the reflected color of the actual object, the color implementation method used inside the computer may be different from the method of realizing the color output from the computer to the actual object. In addition, Hue, Saturation, and Brightness of a color play an important role in color performance. For example, the depth, brightness, and gloss of each color are determined by the HSB. Because the computer's page displayed in RGB mode must be printed in CMY mode (or CMYK mode), it is necessary to convert the color from RGB mode to CMY mode, and the color printer that is responsible for outputting color, in this color conversion work, How close the output color is to the standard color of the CMYK mode is to analyze how its color accuracy is.

However, due to factors such as printer droplet size, print control, color ink amount, and ink quality, it is difficult to print a standard color using a printer, so in fact each printer has a certain degree of color deviation. Only a printer with good performance does not make people aware of the deviation. However, some printers with poor quality and poor quality inks will have more significant deviations.

Second, how to test the color accuracy of the printer?

The best way to test the color error of a printer is to use the printer under test directly to print a variety of colors (especially the four primary colors of cyan, red, yellow, and black), and then compare the printed effect with the standard colors. Therefore, when we test its color accuracy, qualified users can purchase a dedicated standard swatch, then use Photoshop software to copy and print a standard swatch, and then compare the counterfeit and the genuine product to identify the color of the printer. Error conditions. However, if you do not want to compare the color error of the printer with a standard swatch, you can use the following techniques for testing.

Standard swatch

First, use Photoshop's color-changing tools to make a long bar with all the base tones, then print out the long bar with the printer under test, print out the bar, and then use the printed bar picture to compare it with Photoshop. Bars to analyze the printer's color error situation. If you want to know more about the specific color error value, you can use the scanner to scan the printed long picture into your computer. Then, in the Photoshop "Information" window, you can compare the difference between the two different color areas. Of course, because the scanner will also be affected by the color accuracy, the effect of re-entering the photo of the computer may be further error, but usually the accuracy of the scanner's color judgment is much higher than the printer, so the photos scanned again into the computer is still relatively Trusted.

Third, how to improve the printer's color accuracy?

In order to maximize the color accuracy of photos when printing, we should first select a good printer and try our best to use original ink cartridges. However, in the case of printers that have no choice and need to use general-purpose consumables for consumables costs, we can also improve the accuracy of print color by creating ICC color profiles. Currently, there are many specialized software for making ICC color profiles, such as Adobe Gamma, Monaco EZcolor, Monaco Profiler, Printopen, GretagMacbeth ProfileMaker, and Praxisoft WiziWYG, which all allow users to manually create ICC color profiles. These softwares will be compared to each other based on the effects of printing and the effectiveness of the IT8 color metric target (or a dedicated standard swatch, which is usually attached with the scanner, or can be purchased at a bookstore or a chemical store that is engaged in the color industry). Get the appropriate ICC color profile.

Here is a hint, ICC (International Color Consortium, International Color Consortium, the International Color Consortium) is the development of the ICC Profile format of the international standards organization, the format has become the industry standard to describe and deal with the color gamut of different color devices, and now most of the Windows application software are compatible ICC and ICM profiles. Although ICC color profiles are usually included with the monitor, printer, and scanner driver, it is not uncommon for the original ICC color profile to appear to be inapplicable, depending on the device's specific usage (for example, using general-purpose consumables). At this time, the user is required to customize the ICC color profile file according to the specific conditions of the device.

After the ICC color profile is produced, in order to check whether these color profiles are applicable, we can print and preview it first to see if the preview's effect matches the color of the original picture, so as to analyze the application of the color profile. degree.

Printed photos, in addition to the degree of exquisite, the degree of color is also a very critical factor. It is believed that through our introduction, you will be able to adjust your printer and print colorful, authentic works.

Reproduced from: IT168