Computer color matching system to prepare perfect color
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Color is our perception of the outside world; we live in a colorful world, and various colors influence us at all times. The gloomy sky is depressing, the blue sky and white clouds are refreshing, and the spectacular sights of the rainbow make people forget to return.
Color also plays an irreplaceable role in the packaging and promotion of products. In fact, color has emerged in commercial propaganda and continues to grow, bringing us into a state of full color. As a result, some products are increasingly demanding color in design and packaging, and it is especially important for ink and printing companies to accurately color and maintain the color consistency of each batch.
People have a history of color physical properties and chemical properties for more than 100 years. Newton demonstrated how to break down "white light" into a series of shades, but at that time, people did not have sophisticated measuring equipment like today. The spectrophotometer is more consistent and reproducible than the human eye, and when connected to a computer, it can process data at incredible speeds. This article briefly introduces the economic benefits of color matching and quality control using a computer color matching system.
For the printing house, having a color matching department can reduce costs and improve quality. The color management tools for color matching allow you to quickly obtain color ratios, recycle and reuse waste inks, and maximize the benefits of effective ink management.
In order to maintain ink consistency, the color matching department should check the consistency of the base ink purchased from the supplier and control each batch of ink formulated. Through the software, an acceptable tolerance range is established and the base ink is inspected, which allows for better control of the color of the base ink and easier color matching and printing. The more control the base ink and the formulated ink, the higher the production capacity and profit. Color is the first element of product quality!
Effective color control begins with establishing a standard between the printer and the customer. The target can be torn from a color standard book or a color sample. In the printing industry, the Pantone Formula Guide is the standard commonly used for color matching or communication. However, different versions of the PANTONE are very different in terms of visual and numerical values. To ensure accuracy and repeatability of color measurements, this should be noted when using different versions of PANTONE to avoid disagreements due to different standards used by printers, color schemes or customers.
Formulation changes and lighting conditions are two major factors that cause changes in color perception. Different light sources emit different light. The same object has different colors under different light sources with different emission spectra. The printing industry uses 5000K light source (D50) or 6504K (D65) as the standard light source for viewing color samples. Of course, no matter which standard light source is used, it is important to use the same light source to detect color. Otherwise, a different feeling of color is inevitable. Only by communicating these factors with customers can you avoid unnecessary troubles caused by color problems.
The computer color matching software calculates the recipe for a target color. The color of the desired formulation is measured with a spectrophotometer, the measured reflectance data is transmitted to a computer, and the reflectance data is converted to CIE Lab for communication. The color matching software then selects the necessary base ink or recycled waste ink to calculate the best recipe (as shown in Figure 1).
Choosing one of these recipes that best matches the target color is the job of the color matching software. For the best formulation, the reflectance spectra of the given formula and the target color should coincide, or at least be close together; you can also choose the appropriate formula based on cost.
Of course, you should first create a database before using color matching software. The database mainly uses colors corresponding to the PMS or other colors not supported by the Pantone Guide. The accuracy of the recipe calculation is directly related to the base ink, so the base ink provided by the supplier should have good consistency in viscosity and color.
To create a database, dilute each of the base inks with a colorless component (filler). The dilution concentration of various inks should be strictly weighed and accurately recorded. A color sample is applied to each of the different concentrations of ink at the same thickness. When choosing a substrate, choose a bright substrate as much as possible, because the spectrophotometer can measure the dirty spots of the substrate very sensitively and accurately, and add black as compensation when calculating the ratio.
To recycle and reuse the remaining ink, draw the remaining ink into a color sample, and input the measurement into the database with a spectrophotometer. The ink contains the properties and batches of the ink. These colors can be used when matching colors. When these inks are used in color matching, the database updates the inventory information based on the quantity used. The use of this feature is time consuming and requires specialized training and skills, but it does significantly reduce purchases and inventory.
The color matching system uses data to describe the color difference between the sample and the standard under different light sources and to indicate the deviation of the sample from the standard (Figure 2). It decomposes the three-dimensional color space Lab or LCH into an L-axis and an ab or Ch floor plan. It is based on a color that is not both yellowish and bluish, nor reddish and greenish at the same time. The L value is from 0 to 100 and represents the brightness. If the L value is zero, it means no reflection (black) and 100 is full diffuse reflection (white).
When preparing the ink, use a stable performance applicator to sample the ink and send it to the pressroom along with a color data sheet. This efficient and informative communication method minimizes printing time.
In short, the human eye is very sensitive to color changes and it is easy to perceive color differences. The spectrophotometer and color matching system can be used to express and communicate colors in detail and maintain color consistency. Of course, to use the color matching system, first of all, the operator must be specially and systematically trained to understand the relevant color theory. Although the introduction of the color matching system is relatively expensive, it has been proved that the reasonable and correct use of the color matching system can reduce the inventory of waste ink by 40%, the consumption of ink can be reduced by 35%, and the time of stopping the ink adjustment can be reduced by 50%.