Raster imaging principle and parameters

A three-dimensional printing image, also called a raster image, is an image formed by interleaving one image sequence. After stereo images are prepared by stereoscopic photography or professional three-dimensional raster image software, they are combined with gratings. The three-dimensional image creation software (3D software) can Solve the difficult problems for you.

The stereo raster image is related to the raster parameters.

(1) raster resolution

The cylindrical lens density (LPI) of the lenticular lens, which determines the resolution and quality of the image.

(2) raster perspective

The distance from the first image to the last image is called the viewing angle. The smaller the viewing angle, the more sensitive the image changes. In other words, the visual angle is different, and the effect of the image seen is also different. In order to ensure the stereoscopic (3D) effect of the image, when making a 3D raster image, according to different viewing requirements, grating materials with different viewing angles are selected.

(3) grating thickness

The grating thickness depends on the focal length of the grating cylinder. Under a certain grating resolution, the smaller the grating angle of view, the longer the focal length of the lens, and the larger the grating thickness, which is the large thickness of the large-format three-dimensional grating image. Raster reason.

(4) Raster images

A raster image refers to a planar image printed on the back of a raster. This image is output in the TIF or EPS standard image format.

(5) "frames" of raster images

Each raster image consists of a sequence of images interleaved. Each image in a sequence of images that make up a raster image is called a "frame" because a "frame" of a raster image can be used to express motion and animation. Therefore, although the printed raster image is a planar image, it is actually A series of inserted frames.

Frames are the most direct elements of a raster image. If you determine the sequence of frames, you can generate a printable raster image with an interpolating tool. This tool is a "rasterizer".
So how can we get a frame image sequence? For stereoscopic images, we can use a stereo camera or a similar system to obtain a sequence of images, and then use match calibration to obtain a frame sequence that can be used for raster images. As for motion and animated images, it is even more straightforward. It can be directly extracted from the time-series images of movies and videos, and can also be obtained from independent image production, composite motion, and animated images.

The number of interpolation frames and the raster resolution of the raster image are related to the resolution of the raster image. The calculation method is as follows:
N = IR / LR

Among them: N-frame number; IR-grating image resolution; LR-grating resolution. For example, if a 72-line raster is used and the resolution of the raster image is 600 dpi, then the maximum number of insertable frames is 8.

(6) The "object" image in the frame
Although the raster image can be directly obtained by a photographic method, a satisfactory frame sequence cannot be directly obtained, and the stereoscopic printing also depends on the stereoscopic photographic technology and the physical object satisfying certain requirements. However, ordinary photos, or flat objects available for shooting are more easily available, such as landscape pictures, portrait photography, etc. If we combine these different scenes together to form the image we wish to obtain and then generate the frame sequence, we can create the raster image we want. We call these individual images that make up the image an "object" image, but to obtain this "object" image requires a corresponding image processing tool.

At present, 3D image professional production software based on digital images, such as 3D4U image software, has emerged in stereoscopic image production, and it is possible to create or synthesize these object images through plane images, which becomes an indispensable tool for generating raster images.

3D image creation software

The emergence of 3D image software simplifies the pre-press production of three-dimensional printing, and provides a technical basis for the expansion of the application of three-dimensional printing. Take 3D4U software as an example to introduce the features and usage of 3D image software.
In the 3D4U software, two basic object pictures are defined, namely a planar picture and a sequence picture.

(1) Plane picture. Stored in MediaBop format (MBF), this image is the same as a normal 2D photo, but it can incorporate a transparent "mask" that outlines the area where the object is located and "masks" the area outside. When the object and other objects are stacked one on top of the other, the masking area name will appear transparent. You can see the pictures behind it. Obviously, such objects will not have 3D stereo features and depth variations.

(2) sequence picture. Stored in MediaBop 3D (MB3D) format, this type of picture contains a "frame" sequence that can be masked, usually a 3D stereoscopic image sequence, or a motion or animation sequence. Each 3D object picture can be seen as a 3D feature, that is, an object with a depth change. This 3D object image can be obtained with a stereoscopic camera frame sequence, properly masked after matching calibration, and then saved as an MB3D format file. It can also be used by a planar object (MBF) in some specific cases. 3D4U software "stereo picture synthesizer" generated.

(3) The frame sequence is composed of object pictures to make a raster image

The "Raster Image Editor" tool in the application software can easily arrange objects on the screen and change their size, position, and sequence. It is also possible to automatically generate a sequence of frames from these objects. When making a 3D image, only the corresponding data is given according to the front-rear depth requirement between the objects, and the 3D image software can generate a correct sequence of 3D image frames. If you need to create animated stereo or moving images, you can manually process the objects in each frame of the image to achieve the desired effect. After the production is completed, each frame of image can be browsed, and the previewer examines the effect of the continuous change of a sequence of frames; afterwards, the frame sequence is made into a raster image.

A frame sequence diagram composed of a plurality of objects can be stored in a MediaGop Group Format (MBGF) file. The MBGF file includes all the information of the original objects constituting the frame and the information constituting the frame sequence, and can be used to make a difference. The raster image, or modified into other frame sequence diagrams.
3D4U series software also adopts MediaBop adaptive vision correction multi-image integration system, which can directly print a digital integrated stereo image from multiple original image series and animation image sequences by computer, adapt to the resolution of different printers, and can also adopt Digital presses print directly onto grating materials of different line widths.

Raster image production process

According to needs and conditions, stereoscopic images can be produced using various tools provided by 3D image professional software. The production process can be divided into the following two categories:
(1) Make a raster image from the existing frame sequence image. The production process is shown in Figure 1.
(2) Make a raster image from the object picture. Before making a raster image, we must first create an object image; the second step is to make a raster image.

Shanghai Lin Ying Electronics Development Co., Ltd. Zhou Wen Source: "Printing Technology - Equipment and Special Printing"