JPH02264372A - Joining method for digital picture - Google Patents

Abstract

PURPOSE:To improve a picture quality by arbitrarily extracting two common points on two pictures being joining objects, joining the both pictures using straight lines linking the two points on the respective pictures as joining lines, obtaining means bright and dark distribution on the respective pictures being the joining objects, and correcting the gradation of the respective pictures. CONSTITUTION:Picture information obtained by a television camera or an electronic microscope is converted into digital data, the two common points on two pictures IMA and IMB photographed by overlapping to each other are extracted, the two pictures IMA and IMB are joined by using the straight lines linking the two points as joining lines LC, the mean bright and dark distribution of the respective pictures IMA and IMB is obtained, and the gradation is corrected. Consequently the pictures IMA and IMB being the processing objects as the digital picture information can be clipped and stuck on a display screen, and by correcting the gradation of the respective pictures IMA and IMB, the density difference of the respective pictures IMA and IMB is eliminated. Thus the gradation, sharpness, picture distortion, brightness and darkness can be improved, and the picture quality is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for joining images, that is, for creating a so-called panoramic photograph by joining a plurality of overlapping and consecutively imaged digital images. In particular, the present invention relates to a method for joining crystal photographs or slab cross-sectional photographs for metallographic inspection while eliminating differences in gradation, discontinuity of joints, etc.

[Conventional technology]

Conventionally, when creating a so-called panoramic photograph by joining multiple photographs, whether landscape photographs or microscopic photographs, an optical camera and a silver halide film are used to image the subject. Each image was enlarged onto photographic paper, printed, developed, and the resulting photographs were joined together by cutting and pasting.

On the other hand, with the development of so-called digital image processing technology, television cameras and scanning electron microscopes (S[!l'
Imaging devices that can obtain images such as 1) as electronic information are becoming widespread. With such a digital imaging device, for example, the quality of a photograph used for metallographic inspection is 1024 x 5 cm square with 256 gradations.
It has been experimentally confirmed that there are no practical problems if an original image of 1024 pixels (approximately 20 pixels per crane) is obtained. Furthermore, when the image information digitally processed as described above is finally printed on photographic paper, a photographic image with 256 gradations and 24 million pixels or more on ^4 size photographic paper poses a practical problem. I know there isn't.

Incidentally, in digital image processing, an object is imaged by a television camera or an electronic IIJwI mirror, and the relationship between the imaging magnification and the size of the image must be maintained until it is printed on photographic paper. Each captured image has differences in brightness due to differences in exposure amount, non-uniformity in brightness on the same image due to lack of peripheral light in the optical system of the imaging device, image shape due to aberration of the optical system, and It has size distortion, etc. For this reason, even when creating a panoramic photograph using conventional ordinary photographs, it is common to trim the taken photographs and join them together using only the central portion.

[Problem to be Solved by the Invention 3] As mentioned above, conventional ordinary photographs that are spliced together for the purpose of metallographic inspection, for example, have problems during imaging and printing due to factors such as exposure and poor focusing of the inspection target area. In addition, conventional methods require skilled techniques for film development, enlargement, printing, etc., and furthermore, the process of joining photos is a very detailed manual process. For this reason, if it becomes possible to combine images with sufficient gradation and resolution through digital processing, affine transformation can be used.

Laplacian etc. make it easy to improve gradation, sharpness, image distortion, brightness, etc.

The present invention was made in view of these circumstances, and
The purpose of this invention is to provide a method for joining multiple digital images.

[Means to solve the problem]

In the present invention, image information obtained by a television camera or an electronic II mirror is converted into digital data, two common points are extracted from two images taken overlapping each other, and these two points are connected. Two images are joined using a straight line as a joining line, and the average brightness distribution of each image is determined to correct the gradation.

[Effect]

With the method of the present invention, it is possible to cut and paste images to be processed as digital image information on the display screen,
Furthermore, by performing gradation correction on each of the joined images, the difference in density between the images can be eliminated.

[Principle of the invention]

Hereinafter, the principle of the present invention will first be explained.

For example, suppose that two digital images, IMA and IMB, have been obtained as shown in FIG.

In this case, both images are imaged with parts of each overlapping each other (0 image 1?). Two arbitrary feature points a and b in lA are extracted, and points a' and b' that are the same as both points a and b are extracted in image IMB.

Next, in each image IMA and IMB, one of the feature points, for example, a and a′, is lost, and both images IMA and I
Overlap MB. Then, either image IMA or I!IIB is rotated around point a in order to defeat the other feature point S and b'' of both images IMA and IMB. Therefore, triangle abb' is an isosceles triangle.

Furthermore, since the distance between bb' is known from the relationship between the orthographic projection position of the image IMA onto the display l1iWJ and the orthographic projection position of the image IMB onto the display screen, the distance between bb' can be determined.

From Fig. 2, the rotation angle θ required to make the However, j: length of ab r: length of bbl required.

After the images IMA and IMB are superimposed in this manner, it is determined which part of the images INA and IMB, with line segment ab as the boundary, to be selected and joined.

That is, (1) Using the shaded area of image INA, both images 11'lA
and 1? (2) Adopt the shaded part of image IMB and join both images IPIA and IMB. (3) Discard the shaded part of both images IMA and IMB and join them.

As described above, both images IMA and IMB are joined to obtain one image.

Next, gradation correction of each image will be explained.

As shown in Fig. 4(a) and mountain), each image IM
The brightness distribution of each pixel of A and IMB is detected in both the X-ring and Y-axis directions. And both images IMA and I? The average brightness distribution of each of IB is calculated, and based on this result, the brightness level of each pixel of both images IMA and IMB or either image is adjusted according to either of the following two formulas.

y-ax+b y = j! og(x+a)+b However, y: Brightness level of pixel after ill adjustment x:! Ili
Brightness level a, b of pixel before adjustment: constant This brightness level adjustment, that is, gradation correction, is performed for each pixel.

By the above-described image splicing and gradation correction, it becomes possible to combine images by eliminating the difference in brightness level between two images and the discontinuous pressure at the spliced portion by manipulating digital image information.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 5 is a block diagram showing the configuration of equipment used to implement the method of the present invention.

1 in the figure is a communication network.

Reference numeral 2 indicates ITV cameras, each of which is connected to an image input device 6.

3 is a CCD scanner, which is connected to an image input device 6.

4 is IIPMA (Electron Probe Mi
croanalyzer: electron beam microanalyzer)
and is connected to the image input device 6.

5 is SUN (Scanning f!1ectron
Microscope: scanning electron microscope)
It is connected to an image input device 6.

Above +7) ITV camera 2. CCD scanner 3,
l1iP? lA4 and 58M5 are image input, respectively.
That is, an image of a metal tissue piece or the like as a subject is captured.

The image input device 6 converts each captured image into digital image information and sends it to the communication network l.

7 is a high-resolution monitor, which is connected to the image editing device 8.

The monitor 7 displays images when the operator performs various operations in carrying out the method of the present invention, which will be described later. The image editing device 8 processes digital image information in accordance with various operations and commands performed by the operator on the monitor 7. do.

Reference numeral 9 denotes a supervising computer, which is connected to the communication network l.

Reference numeral 10 denotes an optical disk, which is connected to the supervising computer 9.

11 is a laser printer, which is connected to the supervising computer 9;

The supervising computer 9 is the control center of the apparatus for carrying out the method of the invention. The optical disk 10 stores processing target and processed digital image information.

The laser printer 11 is used to print the image information stored on the optical disk 10 and the image displayed on the monitor 7 to obtain a hard copy.

Each image input device 11f6, image editing device 8, and supervising computer 9 are interconnected through a communication network 1, and mutually send and receive image information, control instructions, and the like.

FIG. 6 is a flow chart showing the procedure of the method of the present invention.

Sl is an image input and storage step. In this step S1, the ITV force/-72, the CCD scanner 3.
Images captured by EPH^4, 58M5, etc. are captured as digital image information, and stored on the optical disk 10.
Saved. At this time, each piece of image information is given a code for identifying it, and from then on each image is identified by this code.

S2 is an image search step. In this step S2, the operator inputs the identification code of the image he or she intends to process onto the display screen of the monitor 7 via the keyboard, so that the supervising computer 9 searches the optical disk 10 and displays the image on the monitor 7.

At this time, as shown in FIG. 7(a), the effective image range 7(1), more specifically, the range to be printed as a photograph by the laser printer 11, is displayed on both display surfaces 70 of the monitor 7. ing. The searched image IM is defaulted to be displayed at the center of the effective image range 71.

S3 is a step of brightness distribution analysis. This step S
In step S3, the brightness distribution of the image retrieved in step S2 described above is analyzed.

In this process, the average pixel density value for each line in the X-axis and Y-circle directions of each image is calculated using the following formula.

x 11) Calendar However, individual pixel density value in the DIX axis direction Drs Individual pixel density value in the Y axis direction x (1): Average density value of each line in the X axis direction y (1) n
Average density value of each line in the Y-axis direction! -0, 1, 2...
E: The final pixel number S4 of each line is an image pasting step. This step S
In step 4, it is determined where within the effective image range 71 the image displayed on the monitor 7 in step s3 described above is to be positioned. In other words, this is the same operation as pasting a normal photo onto an album mount.

Specifically, by operating the keyboard or mouse, the point at which the center of the image IN should be located is determined, for example, in FIG.
) As shown in FIG. 7(C), by pointing at the intersection of the cross line cursor 72, one piece of the image is moved and positioned so that its centers coincide with each other, as shown in FIG. 7(C).

S5 is a rotation step. In this step s5,
The image is rotated for joining the images in step S6, which will be described later. Specifically, as shown in FIG. Two straight lines LS passing through the center of rotation C.

The start and end points of rotation are specified by Lll. As a result, as shown in FIG. 7(e), the image IM is rotated around the center C from the straight line LS to LE4, and the partial Φ pixels that are outside the area of the original image IM as a result of rotation are discarded. , all pixels in the area of the original image IM that are outside the fiI of the rotated image are converted to "01" (white pixels).

S6 is a bonding step. In this step S6,
A splicing of the two images is performed.

First, as shown in FIG. 7 (fl), the two images IMA and IMB to be joined are displayed on the effective image range 71 by the operation in step S2 described above, and then, as shown in FIG. (in this case, images 1 and IMB) are moved in the same manner as in the pasting operation in step S4 described above, and the overlapping parts of both images τ, images IFIA and IMB are superimposed.In addition, if necessary at this time, One or both images are rotated by the rotation operation in step S5 described above.

Next, as shown in FIG. 7(g), two cutting rectangles SQ for specifying the areas to be erased in both images are specified at two points, the upper left and lower right, on the effective image range 71. Determined by By specifying two points in this cutting rectangle SQ, a joining line LC for joining both images IMA and IMB is determined. Furthermore, by specifying which region of the joining line LC of both images IMA and IMB should be left and joined, unnecessary parts of both images HIA and IMB are erased, and as shown in FIG. 7 Thl, both images are combined. I
An image 11'IC is created in which MA and IMB are joined.

S7 is an image storage step, and S8 is a printing step in which the firewood rack image created by the various operations described above is stored and saved on the optical disk 10. Processing is performed to cause the laser printer 11 to print each image information or the image newly created as described above and displayed on the monitor 7.

〔Effect of the invention〕

This has been detailed above. According to the present invention, differences in density between images or discontinuities at the joined portions that occur when multiple images are joined by conventional conventional photo cutting and pasting are eliminated, and the final photograph obtained is improved. It has excellent effects such as improved image quality, no need for consumables such as films and processing chemicals, and less skill required for the work.

[Brief explanation of drawings]

1 to 4 are detailed explanatory diagrams of the present invention, and the first
The figure is a schematic diagram showing two images to be joined and two identical points on them.
Figure 3 is a schematic diagram showing which area to select when joining two images; FIG. 5 is a block diagram showing the configuration of an apparatus for carrying out the method of the present invention, FIG. 6 is a flowchart showing the procedure of the method of the present invention, and FIG.
hl is a schematic diagram of a display screen showing the procedure of the method of the present invention. 2...ITV camera 3...CCD scanner
4...EPM^ 5...Sll:M? ...
Monitor 9...Supervising computer 10...Optical disk IMA, IMB...Image a, a' b, b'...Same point on two images LC...Joining line

Claims (1)

[Claims] (1) In a method of joining multiple digital images that have gradation and are taken in an overlapping manner, two common points in each of the two images to be joined are arbitrarily extracted, and the two points in each image are combined. A method for joining digital images, characterized in that both images are joined using a straight line connecting the two points as a joining line, and the gradation of each image is corrected by calculating the average of the brightness distribution of each image to be joined.