JP2681087B2 - Horizontal line detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an image processing mechanism for detecting a horizontal line from an image of the outside world in a ship or the like, and an image of the outside world in which the sky and the sea have low contrast is input. The present invention also relates to a horizon detection device capable of stably detecting a horizon even when the input image includes an image of a ship or the like.

[Prior Art] FIG. 2 is a block diagram showing a configuration of a horizontal line detecting device in a conventional image processing mechanism. In the figure, 1 is an image pickup device, 2 is an analog amount video signal obtained from the image pickup device 1, 3 is an A / D conversion circuit for converting the same video signal 2 into digital amount image data, and 4 is the same A / D Digital image data 5 obtained from the conversion circuit 3, 5 is a frame memory for storing the digital image data 4 as an image to be processed, 6 is second digital image data read from the frame memory 5, and 7 is the same image data 6. Differentiating circuit for differentiating an image for one screen in the y direction, that is, the image vertically downward, 8 is image differential data obtained from the differentiating circuit 7, 11 is addition for adding the same image differential data 8 in the x direction, that is, the horizontal image direction. A circuit, 12 is an addition value for one line in the x direction obtained by the addition circuit, 13 is a first line memory for storing addition data for one line in the x direction, and 14 is a one-dimensional read from the line memory. Reference numeral 39 is a peak value detection circuit for obtaining the maximum value of the one-dimensional data 14 in the Y address 38 which is allowed from the altitude information given from the outside, out of the one-dimensional data 14 stored in the same line memory 13. Is a horizontal line Y address obtained from the peak value detection circuit 33.

In FIG. 2, an image of the outside world is picked up by an image pickup device 1, and an analog amount video signal 2 is obtained from the image pickup device 1. The video signal 2 is analog-digital converted by the A / D conversion circuit 3 and output as the first digital image data 4. Hereinafter, this first digital image data 4 will be referred to as F (X, Y). Here, X is a natural number from 1 to N, Y is a natural number from 1 to M, and x coordinate and y
The coordinates are defined as the horizontal and vertical directions of the image,
The value of F (X, Y) is assumed to be P-bit data corresponding to luminance.

The first digital image data 4 is the frame memory 5
Supplied to

Assuming that a series of image data in which X is 1 to N is one line, the y-direction differentiating circuit 7 performs the differential operation of the expression (1) as an example.

DFY (X, Y) = F (X, Y + 1) -F (X, Y-1) (1) Here, the output 6 of the frame memory 5 is F (X, Y).
This is data for two lines of Y + 1 address and Y-1 address of Y).

The output DFY (X, Y) 8 of the y-direction differentiating circuit 7 is added by one line in the x-direction adding circuit 11. That is, one line is added by the equation (2) to obtain SDFY (Y) 12.

Here, SDFY (Y) 12 is stored in the Y address of the first line memory 13.

When the data of Y from 2 to (M-1) is stored in the first line memory 13, the Y-address 38 within the Y address 38 permitted from the altitude information given from the outside for the data 14 is stored. The peak value and the peak address are obtained by the peak value detection circuit 39, and the peak address 34 is taken out as horizontal line information.

[Problems to be Solved by the Invention] FIG. 3 (a) shows an example of the waveform stored in the first line memory 13 in the conventional apparatus shown in FIG. The peak in the center of the figure shows the change in brightness above and below the ship's deck on the horizon, and due to the shadow of the ship, there is no peak to detect the waterline or horizon.

FIG. 4 (a) is also an example of the waveform stored in the first line memory 13 in the conventional apparatus shown in FIG. 2 in the same manner as above, but in the central portion allowed from the altitude information given from the outside. Has several peaks, which are not significant enough to establish that this is a horizon. That is, these peaks are the water line of the ship, the deck, the boundary line between the upper structure of the ship and the sky, the reflection of waves, etc., and it is difficult to identify the water line or the horizontal line.

The present invention has been made to solve such a problem, and the absolute value of the differential in the Y direction of the digital image F (X, Y) is set to 1
The horizontal line is detected by adding the lines to remove the influence of the ship's shadow, etc., and by finding the zero-cross point of the numerical differentiation, and finding the overall peak excluding the noise-like peak.

[Means for Solving Problems] A horizontal line detection device using image processing according to the present invention includes a frame memory for storing digital image data,
Differentiate the digital image data in the y direction, take the absolute value,
A circuit for adding each line, a first line memory for holding the added result, a circuit for numerically differentiating the result, a second line memory for storing the result, and a zero-cross point of the second line memory The first zero-cross detection circuit to be found, the third line memory for storing the data inside the zero-cross points at both ends, and the peak value of the data in the third line memory are obtained, and the peak coefficient and the peak value are given from the outside. A first area selection circuit for obtaining a threshold value and selecting an area equal to or larger than the threshold value in the third line memory, and an area selected by the first area selection circuit from the area range allowed from altitude information given from the outside. A second area selection circuit for further limiting; a second peak value detection circuit for finding a peak value of the data of the third line memory within the output range of the second area selection circuit; It is obtained by a second zero-cross detection circuit for finding the first zero-cross point by searching the data in the direction the line address from the chromatography click value increases.

[Operation] In the present invention, the digital image data F (X, Y) is differentiated in the y direction and the absolute values thereof are added by one line, so that the y direction can be obtained without being affected by the shadows of ships and clouds. It becomes possible to detect the part where the brightness changes drastically, and by taking the numerical differentiation of that part and finding the zero-cross point, it is possible to effectively detect a peak with a width rather than a noise-like peak, and it is possible to detect a horizontal line. Become. As a result, in the image processing mechanism that detects the horizon from the image of the outside world such as a ship, when an image of the outside world with low contrast between the sky and the sea is input, the image of the ship is displayed in the same input image. Even if it is included, the horizontal line can be detected stably.

[Embodiment] FIG. 1 is a block diagram showing a configuration of a horizontal line detecting apparatus according to an embodiment of the present invention.

In FIG. 1, an image of the outside world is picked up by an image pickup device 1, and an analog amount video signal 2 is obtained from the image pickup device 1. The video signal 2 is analog-digital converted by the A / D conversion circuit 3 to generate the first digital image data F
It is output as (X, Y) 4. The first digital image data F (X, Y) 4 is supplied to the frame memory 5 and stored in the frame memory 5 on a screen-by-screen basis. Further, the digital image data 6 read from the frame memory 5 is supplied to the differentiating circuit 7.

The y-direction differentiating circuit 7 performs the differential operation of Expression (1) as an example.

DFY (X, Y) = F (X, Y + 1) -F (X, Y-1) (1) Here, the output 6 of the frame memory 5 is (Y of F (X, Y)).
It is data for two lines of (+1) address and (Y-1) address.

The output DFY (X, Y) 8 of the y-direction differentiating circuit 7 becomes the data 10 of the operation result of | DFY (X, Y) | by the absolute value circuit 9, and one line is added in the x-direction adding circuit 11. It That is, one line is added by the equation (2) ′,
It becomes SDFY (Y) 12.

The SDFY (Y) 12 obtained from the x-direction addition circuit 11 is stored in the Y address of the first line memory 13.

When the data of Y from 2 to (M-1) is stored in the first line memory 13, the output data 14 is
The numerical differentiation circuit 15 performs numerical differentiation according to the equation (3).

Differential average length given from the outside in the above formula (3)
l35 is an integer value experimentally obtained by application.

Data DY as the result of numerical differentiation by the numerical differentiation circuit 15
(Y) 16 is stored in the second line memory 17 and then stored in the first line memory 17.
Is supplied to the zero-cross detection circuit 19 of.

The first zero-cross detection circuit 19 is the second line memory 17
Detects all zero-cross points in the one-dimensional output data 18 of
The data from both ends of the one-dimensional data DY (Y) to the first zero point is set to zero, and the one-dimensional data DYO (Y) 20
Are stored in the third line memory 21. The data 22 stored in the system control unit 21 is the first peak value detection circuit 23.
Supplied to

The first peak value detection circuit 23 outputs maximum value MX data 24 for the output data DYO (Y) 22 of the third line memory 21 and supplies it to the threshold value calculation circuit 25.

The threshold calculation circuit 25 obtains the product TH26 of the maximum value data MX24 and the threshold coefficient α36 experimentally obtained by the application by the formula (4).

TH = MX * α (4) The first area selection circuit 27 compares the threshold data TH26 with the output data DYO (Y) 22 of the third line memory 21, using the product TH26 as threshold data. Consecutive Y addresses that satisfy the following expression (5) are labeled with the same label name, and the label name and the label address 28 are output and supplied to the second area selection circuit 29.

DYO (Y)> TH (5) The second area selection circuit 29 determines at least a part of the allowable area range 37 based on the area range 37 allowed from the altitude information given from the outside, the label name and the label address 28. A label name including a label and a label address 30 are selected, and the same data 30 is sent to the second peak value detection circuit 31.

The second peak value detection circuit 31 includes a third line memory 22.
The maximum value MXX and its address 32 are found within the range of the label address 30 from the one-dimensional data of 1 and the data is sent to the second zero-cross detection circuit 33.

The second zero-cross detection circuit 33 outputs the maximum value MXX, its address 32, and the output data of the first zero-cross detection circuit.
From 20, the first zero-cross point is detected in the direction of increasing Y address, starting from the address with the maximum value MXX,
The value is output as the horizontal line address 34.

FIG. 3 and FIG. 4 are views for explaining the operation according to the embodiment of the present invention.

FIG. 3 (a) shows the result of detecting the horizon by the above-mentioned conventional method. The peak A in the center of the figure captures the deck position of the ship on the horizon and does not detect the waterline.

On the other hand, FIG. 3 (b) shows the result of addition in the x-direction addition circuit 11 via the absolute value circuit 9 according to the embodiment of the present invention. Here, B shown in FIG. 3B corresponds to the central peak A in FIG. 3A, a new peak C is detected adjacent to the B, and this C corresponds to the horizontal line.

FIG. 3B shows the first line memory shown in FIG.
The result corresponding to the output 14 of 13 and further differentiated by the numerical differentiation circuit 15 is shown in FIG. 3 (c).

In FIG. 3 (c), the zero cross points at both ends detected by the first zero cross detection circuit 19 shown in FIG.
D ₁ and D ₂ , and the maximum value in [D ₁ , D ₂ ] is MX. This MX
And the threshold coefficient α36, the threshold TH is determined by MX * α,
When the maximum value is obtained for the area having at least a part in the allowable area range 37 from the altitude information given from the outside among the areas having a value larger than that, it matches MX in this embodiment, and MX Right side (Y address increases)
Go in the direction and find the first zero-cross point E. This zero-cross point E actually corresponds to C shown in FIG. 3B, that is, the horizontal line. This shows the shape shown by the broken line in the vicinity of C in FIG. 3 (b) when viewed as a macro, and the macro peak value shows the zero cross point E in FIG. 3 (c).
You will have found it in.

FIG. 4 shows another image processing example different from the image shown in FIG.

FIG. 4 (a) shows the result of horizontal line detection by the above-mentioned conventional method. Here, there are three peaks A, B, and C in the central portion of the figure, and it is not clear which is the horizontal line.

On the other hand, FIG. 4 (b) shows the result of addition in the x-direction addition circuit 11 via the absolute value circuit 9 according to the embodiment of the present invention. Here, D corresponds to C in FIG.

Further, FIG. 4 (c) shows the result of the numerical differentiation. The peak value MX and the zero cross point E are obtained by the same procedure as in the example shown in FIG. 3, and the E is taken as the horizontal line. The above E also coincides with the point D, and corresponds to the peak position of the broken line in the macro view of the vicinity of D in FIG. 4 (b).

[Effects of the Invention] As described in detail above, according to the horizontal line detection device of the present invention, a frame memory for storing digital image data,
Differentiate the digital image data in the y direction, take the absolute value,
A circuit for adding for each line, a first line memory for storing the result of the addition, a circuit for numerically differentiating the result, a second line memory for storing the result, and a second line memory for storing the result A first zero-cross detection circuit for finding a zero-cross point of the detected data, a third line memory for storing data inside the detected zero-cross points of both ends, and a peak value of the data of the third line memory. The first area selection circuit that obtains the threshold value from the threshold coefficient and the peak value given from the outside and selects the area equal to or larger than the threshold value in the third line memory, and the area range allowed from the altitude information given from the outside. A second area selection circuit for further limiting the area selected by the first area selection circuit;
The second peak value detection circuit for finding the peak value of the data of the third line memory within the output range of the area selection circuit of (1) and the first peak by searching the data in the direction in which the line address increases from the detected peak value. Second to discover the zero-cross point
By adopting the structure with the zero-cross detection circuit of
It is possible to detect a part where the brightness changes drastically in the y direction without being affected by the shadow of the ship or clouds, and it is possible to effectively detect a peak with a width rather than a noise-like peak. In the image processing mechanism that detects horizontal lines from the image of the outside world, when an image of the outside world with low contrast of the sky and the sea is input, and further, when the image of the ship is included in the input image, etc. However, the horizontal line can be detected stably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment according to the present invention, FIG. 2 is a block diagram showing a configuration example of a conventional device, and FIG.
FIG. 4 and FIG. 4 are diagrams respectively showing a concrete example of the detection processing results of the conventional device configuration and the device configuration of the present invention. 1 ... Imaging device, 2 ... Video signal, 3 ... A / D conversion circuit, 4 ... First digital image data, 5 ... Frame memory, 6 ... Second digital image data, 7 ... y-direction differentiating circuit, 8 ... Differentiating data of digital image data,
9 ... Absolute value circuit, 10 ... Absolute value differential data, 11 ... x
Direction addition circuit, 12 ... Addition data for one line, 13 ...
First line memory, 14 ... Absolute value addition data, 15 ...
Numerical differentiation circuit, 16 ... Numerical differentiation data, 17 ... second line memory, 18 ... Numerical differentiation data, 19 ... first zero-cross detection circuit, 20 ... zero-cross point data, 21 ... third Line memory, 22 ... Numerical value differential data (numerical value differential data with zero set from both ends to the first zero cross), 23 ... First peak value detection circuit, 24 ... Peak value, 25 ... Threshold value calculation circuit, 26 ... threshold value, 27 ... first area selection circuit, 28 ... selected area, 29 ... second area selection circuit, 30 ... selected area, 31 ... second maximum value detection circuit , 32 …… Maximum value and its address, 38 …… Second zero-cross detection circuit, 34 …… Horizontal line address, 35 …… Differential mean length of numerical differentiation, 36 …… Threshold coefficient, 37 …… Y address (from the outside Y address allowed from the altitude information given).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Miyamoto 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Rikuo Kitaoka Omaki, Aichi Prefecture Tanaka 1,200 Mitsubishi Heavy Industries, Ltd.Nagoya guidance and propulsion system manufacturing plant (72) Inventor Makio Yamaguchi 1200, Higashi Tanaka, Komaki City, Aichi Prefecture Mitsubishi Heavy Industries, Ltd.Nagoya guidance and propulsion system manufacturing plant (56) Reference JP-A-3-78614 ( JP, A) JP-A-2-236115 (JP, A) JP-A-2-236117 (JP, A) JP-A-60-67873 (JP, A)

Claims (1)

(57) [Claims] 1. An image pickup apparatus for converting an external image into an analog video signal, an A / D conversion circuit for converting a video signal obtained by the apparatus into digital image data, and an image obtained by the circuit. The frame memory that stores the data, the y-direction differentiating circuit that differentiates the image data stored in the memory in the vertical direction of the image, the absolute value circuit that takes the absolute value of the output of the circuit, and the output of the circuit X-direction addition circuit for adding one line of the above, a first line memory for continuously storing the output of the circuit for each line, and a differential average given externally to the one-dimensional data stored in the memory A numerical differentiating circuit for differentiating using length, a second line memory for storing output data of the circuit, a first zero-cross detecting circuit for detecting a zero-cross point from the output data of the memory, and the second line memory. A third line memory for zero-setting and storing data from both ends of the one-dimensional data to the first zero point by the one-dimensional data stored in the memory and the zero-point data detected by the first zero-cross detection circuit. And a first peak value detection circuit for detecting a peak value of the data stored in the memory, a threshold value calculation circuit for calculating a threshold value from the output of the circuit and a threshold coefficient given from the outside, and a circuit obtained by the circuit. Based on a first area selection circuit for selecting an effective area of the one-dimensional data stored in the third line memory based on a threshold value and altitude information given from the outside in the effective area range obtained by the circuit. A second area selection circuit for selecting an allowable area range and a maximum value of the one-dimensional data stored in the third line memory for the area range obtained by the circuit. A second peak value detection circuit, a peak value detected by the circuit and its peak address, and a first zero-cross detection circuit for detecting the first zero-cross point in the direction in which the address increases from the peak value, based on the output of the first zero-cross detection circuit. 2. A horizontal line detection device comprising: two zero-cross detection circuits.