The most popular stereo printing principle and pro

2022-08-11
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Stereoscopic printing principle and technology

release date: Source: China paper industry

in the field of packaging and printing, stereoscopic printing, which reproduces the stereoscopic image of objects in three-dimensional space, has become an important content in the special printing industry. Today, China paper industry will talk to you about the technical characteristics and development prospects in this regard

the principle and characteristics of stereoscopic printing

the principle of stereoscopic printing is to simulate the distance between human eyes, shoot from different angles, and record the left and right pixels on the photosensitive material. When viewing, the left eye sees the left pixel and the right eye sees the right pixel. The printed matter produced according to this principle is called stereoscopic printing

stereo printing has the following characteristics: (1) it can reproduce objects realistically and has a strong sense of three-dimensional. The product image is clear, the level is rich, the image is lifelike, and the artistic conception is profound; (2) The originals of stereoscopic printing are often made of modeling design or scenery shooting, and the printed matter is generally selected as high-quality coated paper and high-strength. 3. The indication error shows "positive before negative after negative" or "negative before negative after positive" on the dial, and individual points are printed with ultra differential temperature ink, so the gloss is good, the color is bright, and it is not easy to fade; (3) The surface of the printed product is covered with a layer of concave convex cylindrical mirror grating plate, which can directly watch the three-dimensional effect of the panoramic picture. From the perspective of people's stereovision of objects, stereovision of objects mainly comes from human physiological factors, experience and psychological factors. In fact, stereoscopic vision is the stereoscopic information formed by integrating these complex factors in the visual process. In terms of physiological factors, there are parallax (binocular parallax and monocular motion parallax), convergence, regulation, etc. Specifically, binocular parallax is the fundamental factor for people to obtain stereo vision, that is, in daily life, when people observe objects, due to the angle of view between the two eyes and other reasons, the object images seen by the left and right eyes will be different, that is, parallax, which gives people a sense of three-dimensional

the effect of stereoscopic images must be reflected by display technology. The stereoscopic display mentioned here refers to the reproduction of stereoscopic information in the three-dimensional space of an image, which is another basic condition for obtaining stereoscopic vision. There are mainly two methods to realize stereoscopic display, namely, two-way display method and multi-way display method

(1) two-way display method. It can be divided into stereoscopic method, two-color filter method, polarizing filter method and alternating segmentation method. No matter which method is adopted, stereo vision is obtained by using the parallax of two eyes to observe the image respectively by left and right eyes. Stereoscopic method: the basic principle of stereoscopic method is to use stereoscope to observe the left and right graphics in 2010 to form a stereoscopic sense. This method has been widely used since it appeared in the 19th century, but special stereoscope must be used, otherwise there will be no stereo vision. Two color filter method: the left and right images are printed in the same plane with red and blue inks respectively, and the printed images are observed through the red and blue filters. Because the color filter and ink are complementary to each other, the image observed through the color filter is not red and blue, but black. Therefore, this method is limited to black-and-white photos and is not suitable for color printing. Coupled with different wavelengths of light entering the two eyes, it is easy to make the eyes tired. Therefore, this method is rarely used except for making aerial maps. Polarizing filter method: project the left and right images on the same plane through mutually orthogonal polarizing filters, and observe the left and right eyes with the same polarizing filters. Although this method requires special glasses, it has been widely used in stereoscopic movies and stereoscopic TVs. Alternate segmentation method: the left and right images are alternately presented on the same plane, and the unnecessary parts in the same period are covered, so as to produce a three-dimensional sense. Because the residual image effect will cause flash, and the price of glasses for masking is high, this method has not been popularized so far

(2) multidirectional display method. There are mainly parallax shielding method and cylindrical lens method. Parallax shielding method: parallax shielding method, also known as parallax slit method, was invented by es in 1930. Its working principle is to segment the left eye image and the right eye image by the slit, expose them on the film, and then develop, print and print. If it is placed at the same position when photographing, so as to have a more comprehensive understanding of the mechanical properties of the material, and the two eyes are also placed at the position where the image is placed, the stereoscopic image can be seen. Using the parallax slit method, if the two images are synthesized, the parallax stereo image can be obtained. If the aperture ratio of the slit is reduced, the synthesis of multiple images can be completed, and the parallax panoramic image can be obtained. In essence, the parallax slit method is inevitable to reduce the amount of light. Therefore, it is rarely used except in cylindrical lens photography. Cylindrical lens method: cylindrical lens can be regarded as a lens plate composed of many convex lens sheets side by side, which has the function of image division. The back of this lens coincides with the focal plane. Due to the image splitting effect of the lens, the images a, B, C and D in each direction can be separated into a, B, C and D and recorded on the focal plane. As long as the left and right eyes are placed at the positions of B and C, the stereoscopic image can be seen

stereoscopic printing workers should consider the art and key points in the design and development of plastic components

photography method of stereoscopic printing

as mentioned above, cylindrical lens stereoscopic printing requires images of the illuminated object seen from all directions. Photography methods include (1) circular arc moving method. This method takes a certain point on the subject as the center of the circle, and the distance from this point to the camera as the radius to make an arc. The camera moves along this arc and takes pictures continuously or intermittently; (2) Parallel moving method. Move the lens in parallel around the center line of the object. When shooting with this method, the accuracy is not easy to master; (3) Straight line shaking method. The captured image will be a little out of shape. However, if higher accuracy is not required, this is a simple method

in addition, the cylindrical lens is not used in photography. Like ordinary cameras, images in all directions are synthesized through the cylindrical lens while moving. Therefore, images in all directions (6-9) cannot be continuous. It mainly includes instantaneous photography. The camera with multiple (6-9) lenses is most suitable for outdoor photography, especially the photography of moving objects, because it is easy to carry. However, stereoscopic photos cannot be formed without post synthesis. When image synthesis, it has the advantage of magnifying the size. Ordinary camera moving method: install the ordinary camera on the electric chute and take photos while sliding. Compared with the above instantaneous photography method, it has no outstanding advantages, but there is no need for a special camera. The method of using cylindrical lens in photography can continuously photograph within the effective angle. Stereoscopic images can be obtained at one time, but it is very difficult to enlarge after photography, and the exposure time is long, so moving objects cannot be photographed, and the camera is large, which is not suitable for handling. The subject moving method is the opposite of moving the camera. It makes the illuminated object rotate and move in a straight line

the center of the large turntable is consistent with the center of the subject, and photography is carried out while the turntable moves. Use a special indoor camera, which cannot shoot moving objects; Camera parallel moving method: use the method of parallel moving camera to take isometric photography of the subject. With the parallel moving, the camera is always aligned with the center of the subject, and a good image can be obtained. However, the camera is very difficult to make, and due to structural constraints, it is only used for indoor photography; Camera straight-line shaking method: This is a slightly simpler method than the above parallel moving method. The camera moves left and right in a straight line, and the lens shakes repeatedly to align with the center of the subject. This method can be used for indoor and outdoor photography; Shutter moving method: this shooting method is limited to indoor close-up cameras. The shutter moving method uses a large aperture lens. With the movement of the shutter in the lens, stereoscopic images in all directions can be taken. This method has less lens moving distance, can be exposed in a short time, and close-up photography will not damage the sense of three-dimensional, especially suitable for portrait photography

at present, there are two methods commonly used to shoot stereoscopic printing originals, namely, arc stereophotography and shutter moving method. Circular arc moving shooting: install the cylindrical lens plate directly in front of the photosensitive sheet, and shoot with a camera whose optical axis is always facing the center of the subject. The total distance of camera movement shall meet the requirements of image reproduction, and is generally controlled at an included angle of 3 ° - 10 °. The grating plate in front of the photographic plate of the camera moves randomly and synchronously with the photographic plate. Each exposure will focus into a pixel under each semicircular column of the grating plate. When the camera finishes shooting at a predetermined distance, pixels fill the entire grid distance. Stereoscopic photos can be obtained after development. Shutter moving shooting: when shooting, the distance of the shutter moving from one end of the lens to the other is 60mm, which is equivalent to the distance between human eyes. At the same time, the grid plate close to the front of the photosensitive sheet also moves correspondingly, and the moving distance is a grid distance, that is, 0.6mm

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