In recent years, as the product packaging, filled with increasingly rich, exquisite. A new product quietly appeared in people's daily lives. Have you ever noticed the lovely little cards included in the food package? Tilt the card or move the card back and forth to see all sorts of wonderful effects.
This is a product made using a lenticular printing technique. It is widely used in packaging and presentation products, commercial advertisements, science and education cartoons, postcards, New Year's cards, anti-counterfeit labels, trademark tag mouse trays, and various types of credit cards. It is also used in the decoration and filling of various products. The printed pattern is continuous, seamless, and has excellent pseudo-reality. Multi-angle printing can be performed simultaneously on the irregular surface of a shaped object. It is now possible to imitate natural patterns such as precious wood, jade, agate, snakeskin, marble, etc., and to compare with the natural materials, the real simulation effect is very difficult to distinguish.
Grating printing is the use of a grating plate to make the image have three-dimensional printing. This kind of print can directly observe three-dimensional stereo images on a two-dimensional planar image without any tools. People watching these products must be curious how it is made? When people observe objects, they can naturally produce three-dimensionality because of the distance between the two eyes of a person. When observing the object, the left and right eyes observe the visual difference between the two eyes from different angles. The various images formed reflect in the brain and produce a sense of perspective and three-dimensionality.
Prepress production is the use of such a principle, the use of cylindrical lens stereoscopic grating to achieve stereoscopic imaging. That is, using human binocular disparity and the sense of depth formed by convergence to achieve a sense of three-dimensional human consciousness. Therefore, theoretically speaking, stereo images can be synthesized only by obtaining a set of images from two or more different observation points.
A cylindrical lens stereoscopic grating consists of a small garden lens with identical structural parameters and properties. This feature makes it have a 'compression' and 'isolation' effect on the image. A cylindrical stereo grating can record many images from different angles in a stripe state on the same image. At the time of viewing, a stereoscopic grating of the same kind of cylinder is also used to generate a depth image with a parallax stereoscopic effect when two eyes of the same scene are seen by human eyes. The cylindrical lens lenticular is composed of cylindrical lenses arranged in a plane. Therefore, a stereoscopic stereoscopic image of a cylindrical lens should be called a one-way autostereoscopic image. Its significance is that only horizontal disparity information can be perceived.
The stereoscopic images produced by the optical method according to the principles of cylindrical lens stereoscopic grating imaging mainly have the following characteristics:
1. A stereoscopic picture must consist of a set of pictures taken from different perspectives on the same scene. Due to the one-way three-dimensional nature of the grating, the position of the group of pictures is required to be at the same height.
2. The synthesized three-dimensional picture is composed of stripes parallel to the axial direction of the columnar grating. The corresponding bits of each picture in a group of pictures are sequentially arranged at the same grating pitch. As shown in figure ! is a three-dimensional picture composed of two pictures. 3 Because of the reason for the location of each picture, the same point has two points on the three-dimensional picture, thus forming a positional shift which is the reason why the three-dimensionality is formed.
The biggest challenge faced by lenticular printing is color separation because the stereoscopic effect of the grating is obtained by separating and recombining the image into a fine grating. The key is that the interlaced scanning software processes the image. Such file data is generally relatively large and requires the computer to have enough processing power to process the scanned image file. In addition, the fine features of the stereoscopic image pixels and the magnifying effect of the lenticular lens grating are more than 120 lines/cm.
Since the three-dimensional picture image is composed of a closely-arranged pixel, after the plate-making and printing, the lenticular plate is composited. Therefore, besides selecting the screen angle, it is necessary to consider not forming a moiré between the screen plates. The screen angle and the moiré formed by the pixel line and the lenticular line. The three-dimensional printing screen angle should not be selected. Because horizontal lines are the most obvious, and. 'Orthogonal to the pixel line and the cylindrical lens line interferes with the sharpness and depth of the image. Because of the three-dimensional printing, a very fine 300-line screen is used. In the printing, only 8.5 or 90% of the printing is used for printing. Otherwise, it is easy to paste the printing when printing. In this case, the color amount of the dark tone area needs to be increased to reach 9 -9.5 points into effect. Therefore, the solid printing density of the color printing ink is higher than that of the four-color printing on the flat surface.
Grating three-dimensional printing requirements are very precise, the current printing process is mainly two ways, one is directly printed on the grating material, the other is printed on the paper and then pasted on the grating or glued onto the plastic film and then out of the grating . The grating thickness is between 0.008-0.385 inches. Therefore, if the printing overprint is not accurate even if the deviation is extremely small, the printed product will become a very small difference between the waste will affect the effect of the entire layout. Therefore, the three-dimensional raster printing requires high precision of the printing equipment, and the overlay error should be less than 0.0lmm.
If it is a paste-type printing process for cylindrical gratings and prints, the process of accurately affixing images and gratings together is critical. Some enterprises are manually operated. There are many uncontrollable links. Workers' operating skills directly affect the quality of stereoscopic images. The method of grating plate sticking and synthesizing is to apply a layer of glossy glue on the finished printed product. The thermoplastic material with high transparency is heated and dissolved in the mold to form a cylindrical grating plate. The plate is attached to the finished printed product. Accurate alignment of the raster lines with the raster lines on the print can show a three-dimensional effect. The lenticular lens pitch is 0.6mm, and the formed concave-convex surface divides the image equidistantly into countless pixels. There are approximately 48 concave and convex lines per centimeter of the cylindrical grating plate and approximately 6 pixels below each concave and convex line. It is not easy to precisely align the raster lines on the printed lines and the raster lines on the prints. The printing process directly printed on the grating material is relatively easy, and the finished product can be directly printed as long as the accuracy of the machine is reached. However, unlike traditional printing, it is necessary to coat the printing surface with a layer of white glossy oil.
Although the theory of stereo photography has suggested that the master has a history of less than 100 years, the actual application of this technology has been very long. The raster stereoscopic printing originates from the three-dimensional image negative film provided by stereo photography. However, due to stereoscopic photographs in the shooting and production of the use of traditional optical principles of the production and synthesis of stereoscopic photographs in the application of the very large limitations coupled with high requirements on the accuracy of equipment, process technology complex and high production costs. Therefore, three-dimensional photography has not been promoted and popularized. At the same time, three-dimensional printing has been subject to cumulative errors between the long process of prepress production processes. Difficulty in operation, low efficiency, poor quality, high scrap rate, and the need for expensive special manufacturing equipment and consumables are also major obstacles to the application and development of raster three-dimensional printing technology.
In the 21st century, stereo photography entered the digital era. People used computer software to perform multi-image synthesis. Computer technology, especially the rapid development of image input, processing and output technologies, has provided convenience for computer synthesis of stereoscopic pictures.
With the advent of computer-to-plate CTP technology, high-precision printing with FM networks is used. UV technology applications continue to mature, many equipment manufacturers have introduced a variety of models of UV offset press. Heidelberg, Manroland, KBA, Komori, and Ryobi have all introduced offset presses with this capability. The use of offset printing machines to directly print plastic grating materials is no longer a problem. The three-dimensional printing quality system has been guaranteed. The three-dimensional raster printing has achieved rapid development. In recent years, the domestic three-dimensional printing has been greatly developed. The printing factory began to use grating stereoscopic printing technology to obtain more complex products. From labels, poster posters to packaging products, and even plastic cups have applied three-dimensional printing to present a thriving scene.
Although what is seen on the product is not a true stereoscopic effect, raster stereo printing is not just a trick to kidding children. Compared with the traditional three-dimensional photo production process, it shows its unique advantages in terms of economy, flexibility of use, etc. We have reason to believe that the grating three-dimensional printing technology will have a broader application space and development in the future printing field. prospect.
Source: Printed Today