JP2001167266A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of aliasing on a monitor display image with digitizing of an image. SOLUTION: Concerning the image processor, with which an image suitable for observing an optical fiber or the like can be outputted on a TV monitor by applying various kinds of processing to image data provided by digitizing video signals from a TV camera for photographing the light transmissive images of the optical fiber or optical component, this device is provided with a correction circuit for performing anti-aliasing processing for canceling aliasing on the TV monitor display image. A pairing phenomenon is utilized for anti-aliasing processing. In anti-aliasing processing, intensity distribution fitting of pixels is considered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for processing an image photographed by a TV camera, and more particularly to an image processing apparatus for photographing an optical fiber or an optical component by the TV camera.
In order to process this image and output an image suitable for observation of the optical fiber or the like to a TV monitor, or to output information necessary for optical axis alignment of the connected optical fiber or optical component. The present invention relates to an image processing apparatus to be used.

[0002]

2. Description of the Related Art An optical fiber fusion splicing apparatus uses a TV camera to photograph a transmitted light image obtained by irradiating an optical fiber with light from the side thereof, and applies a necessary processing to the photographed image to a TV. In some cases, necessary information is output to a monitor or obtained from the image, and a series of operations from optical axis alignment of the optical fiber to fusion splicing are controlled based on this information. This type of optical fiber fusion splicing device includes positioning pedestals C and D for separately setting two optical fibers A and B, as shown in FIG.
A light source E for illuminating the optical fibers A and B set on D from the side, a TV camera F for capturing an image of light transmitted through the optical fibers A and B, and an image for processing an image of the TV camera F A processing device G, and a drive control circuit I for driving a motor H for moving one of the positioning pedestals C based on a signal from the image processing device G. The image processing device G converts the image input from the TV camera F Processing, the same device G
A video signal is output to a TV monitor J connected to the monitor, an observation image is displayed on the monitor J, a control signal is output to a drive control circuit I, and a motor H is driven to move one positioning pedestal C. By doing so, the optical axes of the optical fiber A set on the pedestal C and the optical fiber B set on the other pedestal D are aligned. In addition, a microscope K is attached to the end of the TV camera F in order to magnify and photograph an abutting portion of the optical fibers A and B.

[0003] Here, the operator visually confirms whether or not the optical axes of the two optical fibers coincide with each other based on the observation image displayed on the TV monitor.
The image displayed on the TV monitor is required to be as accurate as possible and easy for the operator to see. In order to satisfy such demands, the present inventor has developed various image processing methods and image processing apparatuses to date and applied for patents (Japanese Patent Application No. 7-14 / 1995).
7746, Japanese Patent Application No. 10-21098). Although a detailed description of the image processing method and apparatus for which the present inventor has already applied for a patent is omitted here, these processing apparatus and processing method basically apply a video signal input from a TV camera to A / A. D-converted and digitized to obtain image data, and by subjecting the image data to a scan conversion process, the image obtained by rotating the image of the TV camera by 90 degrees is converted to a T
It is possible to display images on two or more TV cameras in the vertical direction and / or the horizontal direction, or to enhance or reduce the images of two or more TV cameras so that two or more images can be displayed collectively on one screen of the TV monitor. Or something.

[0004]

The image processing method and the image processing apparatus developed earlier by the present inventor have no particular problem, and have been well received in the market. With the digitization of the signal, the image (video) displayed on the TV monitor becomes jagged, and there is a problem that the operator may feel uncomfortable. Such jagged images are a phenomenon called aliasing in the field of image measurement.
In general, for example, when a digital curve is displayed in binary black and white, it is often handled by giving a jagged gradation, and it is known that a low-pass filter is used in this case. Specifically, as shown in FIG. 13, the gradation of the target pixel is determined based on the gradations of the pixels surrounding the target pixel, for example, the eight surrounding pixels, and the determined gradation is given to the target pixel to cause aliasing. Has been eliminated. Wherein the pixel tone ⁽ⁿ P ^v) is calculated according to the following equation. In the above formula, This is the luminance of the pixel at the coordinates.

It is also known to use a histogram as a means for eliminating aliasing. Specifically, as shown in FIG. 14, the mode of black (PB) and the mode of white (PW) are obtained from the frequency of each gradation of the pixel, and the brightness is assigned by equally dividing the mode. And is often used for processing line pixels. More specifically, as shown in FIG. 15A, when the coordinates of the pixels forming the line segment in the vertical direction of the surface around the center of the line pixel are different, the result of the histogram is applied to this, The pixel is given a gradation as shown in FIG. 3B, and the upper pixel is provided with a gradation as shown in FIG.

The above-described conventional aliasing elimination means has a sufficient effect in applications such as drawing graphics. However, the observation of an optical fiber has the following disadvantages. (1) Since the entire image is a target, the image displayed on the TV monitor is totally blurred, and observation of an optical fiber or an optical component for the purpose of alignment using a steep light-dark difference at a boundary is required. Not suitable. (2) There is a lot of data that is the source of the arithmetic processing, the processing takes a long time, and the speed of the processing is increased, so that the scale of the arithmetic circuit becomes large. However, when observing optical fibers and optical components for the purpose of alignment and the like, high-speed real-time processing is desired, and miniaturization and weight reduction of the apparatus are also desired.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing apparatus capable of performing aliasing processing suitable for observation images of optical fibers and optical components and performing the processing at high speed. To provide.

The present inventor paid attention to the characteristics of the transmitted light image of the optical fiber in order to achieve the above object. Specifically, the optical fiber is about 40% between the surrounding air and the cladding,
It has a refractive index difference of about 0.3% between the cladding and the core. In addition, when the optical fiber is irradiated with parallel light from the side of the optical fiber, the optical fiber itself becomes a cylindrical lens, and the light passing through the fiber cross section is bent toward the center due to the difference in the refractive index, so that the light is denser than the coarse part. Contrast occurs between the part and other parts. FIG. 16 shows the light in the optical fiber when the parallel light is irradiated from the side of the optical fiber, the resulting image, and the contrast on the measurement line in the image. The right side of FIG. 16 shows the light in the optical fiber when the parallel light is irradiated, the center shows the image resulting from the light irradiation, and the left side shows the contrast (luminance level) on the measurement line. is there.

As described above, in the transmitted light image of the optical fiber, the correlation in the direction parallel to the optical fiber (axial direction) is very strong, but the correlation in the orthogonal direction is weak. Further, in the orthogonal direction, the luminance level changes abruptly at the boundary between light and dark. The image processing apparatus of the present invention focuses on the characteristics of the transmitted light image of such an optical fiber, utilizes the pairing phenomenon of pixels in a direction perpendicular to the optical fiber, and further considers the fitting of the luminance distribution of the pixels to digitize error. Is corrected to enable high-speed aliasing processing with a simple circuit. Specifically, this is as follows.

A first image processing apparatus according to the present invention takes a light transmission image obtained by irradiating an optical fiber or an optical component with light using a TV camera, digitizes a video signal from the TV camera, and converts the image into a digital signal. Various processes for outputting an image suitable for observing an optical fiber or an optical component, such as an image obtained by rotating the image of the TV camera by 90 degrees or an image reduced or enlarged in the horizontal and vertical directions, to the TV monitor. An image processing apparatus capable of performing an anti-aliasing process for eliminating aliasing of an image displayed on a TV monitor.

According to a second image processing apparatus of the present invention, the first image processing apparatus comprises:
In the above image processing apparatus, the correction circuit utilizes the pairing phenomenon in the anti-aliasing processing.

A third image processing apparatus according to the present invention comprises the first image processing apparatus.
In the above image processing apparatus, the correction circuit performs processing in consideration of luminance distribution fitting of pixels in anti-aliasing processing.

A fourth image processing apparatus according to the present invention comprises the first image processing apparatus.
In the above image processing apparatus, the correction circuit utilizes the pairing phenomenon and further performs an anti-aliasing process in consideration of the luminance distribution fitting of the pixels.

[0014]

(First Embodiment) A first embodiment of an image processing apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of an optical fiber fusion splicing apparatus provided with the image processing apparatus of the present invention. This optical fiber fusion splicing device includes two optical fibers 10, 1 as shown in FIG.
1 is provided with positioning pedestals 13 and 14 for separately setting one of them, and one of the positioning pedestals 13 receives a signal from the motor 16 and the image processing apparatus 20 of the present invention and controls the motor 16. A drive control circuit 22 is connected, and is automatically controlled based on a signal from the image processing apparatus 20 and can be moved. As shown in FIG. 1, the optical fiber fusion splicer includes a light source 24 for illuminating the optical fibers 10 and 11 set on the positioning pedestals 13 and 14, and an image of light transmitted through the optical fibers 10 and 11. A TV camera 1 for taking (light transmission image) is provided. As shown in FIG. 1, the TV camera 1 is connected to an image processing apparatus 20 of the present invention, and the image processing apparatus 20 is connected to a TV monitor 2 for observing a captured image. A microscope 25 is attached to the end of the TV camera 1, and two optical fibers 10 and 11 are provided.
It is possible to take a picture by enlarging the abutting portion of. In FIG. 1, only one set of the TV camera 1, the light source 24, and the microscope 25 is provided. However, when performing observation from multiple directions, many sets of these can be prepared. In this case, it is natural that the image processing device 20 can support multiple inputs.

The image processing apparatus 20 of the present invention comprises an input circuit 30, an A / D converter 31, a frame memory 32, an arithmetic circuit 33, a graphic circuit 34, and a synthesizing circuit 35 as shown in FIG. The video signal input from 1 is input to an A / D converter 31 via an input circuit 30, digitized and branched, and one is recorded in a frame memory 32. The image data recorded in the frame memory 32 is read out by the arithmetic circuit 33 in the next stage and
3 to obtain information necessary for adjusting the optical axes of the optical fibers 10 and 11 from the image, and control the drive control circuit 22 (FIG. 1) to control the motor 16 (FIG. 1). A signal can be output. The arithmetic circuit 33 outputs information such as the result of the image processing in the circuit 33 and the progress of work to the graphic circuit 34, and the graphic circuit 34 outputs a video signal including text (characters) and graphics (graphics). Is generated, and the video signal is synthesized by the synthesizing circuit 35 with the video signal transmitted from the TV camera via the scan converter 36 and output to the TV monitor 2. The input circuit 30 is a DC reproduction circuit, an amplifier, a video encoder, and the like, and is constituted by necessary components depending on the format of the input video signal. The scan converter 36 is for performing the scan conversion process described in the section of the related art, and basically, the image of the TV camera 1 is changed by changing the read / write address of image data to a memory (not shown). Is output by rotating the image by 90 degrees. The scanning converter 36 shown in FIG. 2 can be changed to a reduction processing circuit that performs the emphasis processing and the reduction processing described in the section of the related art and can collectively display two or more different images on one screen.

As shown in FIG. 2, of the image data output from the A / D converter 31 and branched, the other image data is input to the correction circuit 3. This correction circuit 3
As shown in the figure, a delay circuit 40, modulus multipliers 41 and 42
And the adder 43, and the image data input to the correction circuit 3 is further branched.
The signal is input to the coefficient multiplier 41 via 0, and the other is input to the coefficient multiplier 42 directly. As a result, two digital values are obtained by multiplying each of the immediately preceding pixel and the current pixel by a coefficient that takes into account a pairing phenomenon described below and a distribution fitting of pixel luminance. The obtained two digital values are added by an adder 43 to obtain a corrected current pixel, and the corrected value is output to the next-stage scan converter 36, where necessary processing is performed. By outputting to the monitor 2, the aliasing of the image displayed on the monitor 2 is eliminated.

Here, the above-mentioned pairing phenomenon is a phenomenon in which one pixel feels as if it is shining at a position intermediate between the two pixels if the light emission luminance of two adjacent pixels is properly adjusted. A specific description will be given based on FIGS. One pixel having the luminance as shown in FIG. 3A is displayed on the TV monitor as shown in FIG. Also, as shown in FIG. 3C, two adjacent pixels whose total sum of the luminance is equal to or slightly higher than the luminance of one pixel in FIG. 3A are displayed on the TV monitor. As shown in FIG. 3D, the hem portions overlap each other, so that the human eyes feel as if they were fused, and one pixel is located at the midpoint between the two pixels as shown in FIG. The illusion that exists exists, and the human eye sees Fig. 3 (b)
Will be recognized as well. This is a pairing phenomenon, and aliasing can be eliminated by using such a phenomenon. The intermediate point can be moved more finely by changing the distribution of the luminance of the two pixels.

The digitizing error is an error as shown in FIG. 4 when a continuous analog signal is digitized by sampling, and the output digital signal has a noise generally called quantization noise. Exists. In order to correct this error (to eliminate noise), it is necessary to perform luminance distribution fitting as shown in FIG. Here, in a processing system for an image having a large black-and-white contrast such as a transmitted light image of an optical fiber, a step-shaped image may be considered. Therefore, a case where correction using only the pairing phenomenon is performed on the step-shaped image will be described. FIG.
FIG. 7 shows a case where correction is performed in consideration of fitting using the pairing phenomenon. Comparing these FIGS. 6 and 7, it can be seen that aliasing can be more effectively eliminated when fitting is considered than when only the pairing phenomenon is used.

In the case where the above-described pairing phenomenon is used to apply the correction in consideration of the fitting to the observation of the transmitted light image, it is necessary to perform the correction in the direction of the measurement line in FIG. At this time, the calculation is simplified by configuring a processing system synchronized with the scanning. That is, the data can be simplified by appropriately calculating and synthesizing the data of one pixel unit and the immediately preceding data of one pixel unit sent in the scanning order of the TV camera to obtain the current data of one pixel unit. In order to perform such arithmetic processing, the correction circuit 3 shown in FIG. 2 branches the input data VI7 to VI0 as shown in FIG. 8, and one of the input data VI7 to VI0 enters a delay circuit (latch) 40 and receives one by a pixel clock (CLK). A7-A of the adder 43 after receiving the pixel time delay
0, and the other enters B7-B0 of the direct adder (binary adder) 43. As a result, the current data and the data one pixel before are input to the adder 43. The adder 43 performs 8-bit and 8-bit addition,
As a result, carry (CO) and the operation results Y7 to Y
Take 1 and discard the operation result Y0. As described above, 1/2 of the addition result, that is, the average value can be obtained as the correction values VO7 to VO0, and the correction in consideration of the fitting can be performed at high speed using the pairing phenomenon. In FIG. 8, the coefficients are treated as 1 and the coefficient multipliers 41 and 42 are used.
(FIG. 2) is omitted.

(Embodiment 2) FIG. 9 shows an example of the correction circuit 3 in the image processing apparatus of the present invention. The basic configuration of the correction circuit 3 is the same as that shown in FIG. The difference is that a value obtained by multiplying the input pixel data by a coefficient is written, and PLDs 50 and P functioning as a coefficient calculator are written.
By providing the LD 51, the PLD 50, PLD
That is, the rate of correction can be changed depending on the value to be written in 51.

FIG. 10 shows another example of the correction circuit 3 in the image processing apparatus of the present invention. The basic configuration of the correction circuit 3 is the same as that shown in FIG. The difference is that in a transmitted light image of an optical fiber, jaggies (aliasing) are conspicuous in steep light and dark areas, so that only a sudden change in pixel data is corrected. Specifically, as shown in FIG.
The reference data is compared with the input data VI7 to VI0. If the input data is equal to or less than the reference data, the input data is output through the buffer 61 without modification. When the input data exceeds the reference value, the result of the correction operation by the adder 43 is output.

FIG. 11 shows still another example of the correction circuit 3 in the image processing apparatus of the present invention. The basic configuration of the correction circuit 3 is the same as that shown in FIG. The difference is that only VI7 is 1 for input data VI7 to VI0.
That is, the flip-flop 70 is inserted so as to be delayed by the pixel time. As a result, the transmitted light image of the optical fiber changes abruptly, so that when the MSB of the pixel data changes, it works to distribute the luminance of two pixels adjacent to each other. An effect close to 3 is obtained.

The image processing apparatus according to the present invention is not limited to a process for outputting an image obtained by rotating the image of the TV camera by 90 degrees or an image reduced or enlarged vertically and horizontally to a TV monitor. As a prerequisite for performing various processes required to output a suitable image for observation to a TV monitor, in all cases where a video signal from a TV camera is digitized, in order to eliminate aliasing in a display image on the TV monitor. Can be used for

[0024]

The image processing apparatus according to the present invention has the following effects. There is no aliasing even if the video signal from the TV camera is digitized to provide an image obtained by rotating the image of the TV camera by 90 degrees or to display two or more images on one screen. A smooth image is displayed on the TV monitor, and the operator viewing the monitor does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an optical fiber fusion splicing apparatus including an image processing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a first embodiment of the image processing apparatus of the present invention.

FIGS. 3A to 3E are explanatory diagrams showing a pairing phenomenon.

FIG. 4 is a diagram showing that a digitizing error (quantization noise) occurs when a continuous analog signal is digitized.

FIG. 5 is a diagram showing a luminance distribution fitting for eliminating a digitizing error.

FIG. 6 is an explanatory diagram showing a case where only correction using pairing is performed.

FIG. 7 is an explanatory diagram showing a case in which a pairing is used and a correction is performed in consideration of fitting.

FIG. 8 is an explanatory diagram showing details of a correction circuit shown in FIG. 2;

FIG. 9 is an explanatory diagram showing a correction circuit including a PLD functioning as a coefficient calculator.

FIG. 10 is an explanatory diagram illustrating a correction circuit including a comparator and a buffer.

FIG. 11 is an explanatory diagram illustrating a correction circuit including a flip-flop.

FIG. 12 is a schematic view showing an example of a conventional optical fiber fusion splicing apparatus.

FIG. 13 is an explanatory diagram showing a case where a gradation of a target pixel is obtained from surrounding pixels.

FIG. 14 is an explanatory diagram showing the principle of aliasing elimination means using a histogram.

FIGS. 15A to 15C are explanatory diagrams specifically showing the principle of aliasing elimination means using a histogram.

FIG. 16 is an explanatory diagram showing characteristics of a transmitted light image of an optical fiber.

[Explanation of symbols]

 1 TV camera 2 TV monitor 3 Correction circuit

Claims (4)

[Claims] 1. A light transmission image obtained by irradiating an optical fiber or an optical component with light is photographed by a TV camera, and a video signal from the TV camera (1) is digitized.
The image of the TV camera is added to the digitized signal by 90
An image processing apparatus capable of performing various processes for outputting an image suitable for observing an optical fiber or an optical component, such as an image rotated by degrees or an image reduced or enlarged in the horizontal and vertical directions, to the TV monitor (2). And a correction circuit (3) for performing anti-aliasing processing for eliminating aliasing of an image displayed on the TV monitor (2). 2. An image processing apparatus according to claim 1, wherein said correction circuit uses a pairing phenomenon for anti-aliasing processing. 3. The image processing apparatus according to claim 1, wherein the correction circuit performs processing in consideration of luminance distribution fitting of pixels in the anti-aliasing processing. 4. An image processing apparatus according to claim 1, wherein said correction circuit uses a pairing phenomenon and further performs anti-aliasing processing in consideration of luminance distribution fitting of pixels. apparatus.