Design of the hottest stereo printing

Design of stereoscopic printing

1 Due to the influence of human eye resolution, the relationship between grid distance (P), thickness (d) and observation distance (d) enables us to distinguish more details of nearby objects, while the ability to detect details of distant objects will be greatly reduced. For the grating on the stereo image, if we can clearly distinguish the grating cylindrical mirror, it will interfere with our visual experience and affect the performance of the stereo image. When the thickness is constant, the decrease of the grid distance will increase the observation distance. Therefore, we should not only change the grid distance, but also comprehensively consider the factor of thickness. If the thickness of the grating plate is reduced under a specific grid distance, the observation distance will become smaller. Therefore, the grating plate used for close observation should be thin and dense. For grating plates used for long-distance observation, if the grid distance is too small, some details of the drawn image will be lost, which will affect the observation effect. Similarly, in order to meet the requirements of wide grid spacing, it is necessary to increase the thickness of the grating plate. Therefore, the grating plate used for long-distance observation should be thick and sparse

to sum up, when manufacturing grating plates, it is necessary to first determine the appropriate grid distance according to the required observation distance, and then determine the thickness of the grating according to the observation distance and grid distance

2. Parameter analysis

the above analysis is based on the relationship between parameters, and the following analysis is based on the impact of parameter selection on image effect

① number of grating lines (LR)

number of grating lines refers to the number of grating bars per inch unit, which is the reciprocal of grid distance P. The number of lines of the grating is expressed by LPI, that is, the number of cylindrical mirrors within 1 inch. Generally, gratings suitable for printing include 75lpi, 100lpi, 120lpi, 150lpi, etc

the number of raster slices determines the accuracy of stereo images and limits the resolution of raster images. The higher the number of lines of the grating slice is, the higher the resolution of the grating image is required, and the precision of the final stereo image will be higher; If the number of lines of the grating is lower, the resolution of the grating image is not too high, and the accuracy of the final stereo image is relatively low. The higher the resolution of raster image, the higher the requirements for its output equipment, and the higher the natural output cost. Therefore, when selecting the number of grating plate lines, we should not only meet the accuracy requirements, but also make the production cost within a reasonable range according to the actual situation

the resolution of human eyes to details is limited by the observation distance, so in actual production, the number of lines of the grating should be selected according to the observation distance. The grating plate with high line number shall be selected for close observation, and the grating plate with thick line number shall be selected for long-distance observation

generally, when the observation distance is less than 80cm, 75lpi~90lpi grating plate should be selected, and at this time, the grating plate is thin. When the observation distance is less than 50cm, 75lpi~150lpi should be selected. In addition, the selection of the number of lines of the grating is also affected by the size of the image. When the image size is smaller than A5, the grating plate with more than 75lpi is applied, and the stereoscopic picture produced at this time is delicate and soft

② viewing angle range ()

viewing angle refers to the maximum angle that can be allowed when the research of forming an image or observing an image in plastic, rubber and urban exterior wall coating needs to be further strengthened. The smaller the angle of view, the sharper the change of the image. Therefore, the grating plate with small angle of view can well and delicately express the three-dimensional effect, while the grating plate with large angle of view is mainly used to express animation, transformation and other effects

③ transmittance ()

transmittance is used to express the transparency of grating sheet, which is determined by grating material and processing technology. The higher the transmittance, the better the transparency. Because the stereoscopic image we discussed is pasted on the raster image with a grating plate, and the image is reproduced through the refraction of the grating sheet, the transparency of the grating sheet will directly affect the performance effect of the stereoscopic image. If the transmissivity is high, the loss of image information after refraction by the grating is less, and the brightness of the reproduced image will be stronger; On the contrary, if the transmittance is too low, After the image information is refracted by the grating plate, there will be more damage to the information. Tolstoy once said: "if a person does not lose enthusiasm, it will affect the quality and brightness of the reproduced image. Therefore, try to choose materials with high transmittance to make the grating plate.

④ refractive index (n)

the refractive index is determined by the grating material itself. Under certain other conditions, the higher the refractive index of the grating plate, the larger the angle of view 1, and the better the image division

3. Generally speaking, there are three methods for making raster images: stereophotography, computer generation, and image processing software processing

① stereo photography

stereo photography is a traditional raster image production method. The key operation is to take stereo photos, and it is necessary to accurately calculate the layout, distance, angle, center point, etc. of the subject before shooting. It is divided into direct method and indirect method. The direct method is to place the cylindrical lens grating plate in front of the photosensitive film, move the camera within a certain field of view, and continuously shoot the subject; The indirect rule is to take more than two photos at a specific location, and then combine them accurately into one. When the grating image is made by stereophotography, the details of the image are accurately projected to the surface of the photosensitive material through the grating, and the pitch of the grating stripe is consistent with the width of the image details, so it is very accurate. The stereoscopic effect of the final stereoscopic image is better. However, because stereo photography requires special equipment and is troublesome to operate, the scope of use of this method is also limited, so it is rarely used now

② computer generation method

this method is based on the principle of raster image production, uses the computer to use the corresponding algorithm, thins each frame in the image sequence into vertical strip images, and then synthesizes them alternately in order, and then generates the final raster image through compression processing. This method does not need special shooting equipment, and the operation is simple, By using Photoshop and other image software, you can synthesize raster images after some processing of ordinary images. Therefore, it has been widely used

③ image processing software processing method

this method uses image processing software such as Photoshop to segment each frame in the image sequence by manual operation. And then collage and synthesize the required raster image. Although the principle of using this method is simple, it is troublesome to operate and requires some skills. Moreover, when using Photoshop Image processing software to synthesize images, the dislocation arrangement of image details produced is not the actual dislocation arrangement required. Therefore, the synthesized images often appear very obvious sawtooth phenomenon, which will seriously affect the quality of stereo images under the amplification of grating. The projector is used to accurately detect the processing quality of V-shaped and U-shaped notches of impact samples

by analyzing and comparing the above three raster image generation methods, we believe that the computer generation method is indeed a more feasible method (but the instrument displays normally), so our company has developed its own three-dimensional design software based on the advantages of similar software in the market