JPS6236544B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is for displaying image information expressed in a spiral scan format such as scanning sonar on a display device expressing image information in a TV scan format such as a monitor television. This invention relates to a scan converter that converts an image signal into a scan converter.

The number of spiral scan sweeps obtained with scanning sonar is generally several times greater than the number of sweeps of a normal monitor TV. In order to match the two, there is a method such as extracting one for each sweep of multiple spiral scans and displaying it on a monitor TV, but this method uses only the information that is used by thinning out the sweeps. decrease and impair fidelity.

Furthermore, as will be explained in detail later, if image information sampled at every fixed rotation angle of the spiral scan is simply displayed at the point on the TV scan corresponding to that point, the fidelity will be significantly lost, and the displayed image will be It has drawbacks such as being difficult to use in applications such as scanning sonar, which attempts to determine the presence or absence of fish schools and fish species based on their delicate characteristics.

In order to eliminate these drawbacks, the present invention provides a sweep matching device that matches the number of sweeps without losing the image information of the spiral scan, and a sweep matching device that matches the number of sweeps without losing the image information of the spiral scan. This device has a bright spot correction table for display, and will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
1 is a scanning sonar, 2 is an A-D converter,
3 is a sweep matching device, 3-1 is a first sweep memory, 3-2 is an arithmetic unit, 3-3 is a second sweep memory, 4 is a first controller, 5 is a video memory,
6 is a bright spot correction memory, 7 is a second controller, and 8 is a monitor television.

Next, its operation will be explained.

Image output of scanning sonar 1 is A
(t), the angle signal of the sweep output, and the distance signal are generally illustrated as θ(t) and R(t) as shown in A, B, and C in FIG. 2, respectively. Here (t) is the elapsed time. These signals are A-D
The image output A(t) at that time is transmitted to the converter 2 at a constant angle of the sweep output θ(t), for example, every 1 degree.
Convert to a 3-bit digital value. The period in which the angle signal θ(t) of the sweep output changes once from 0 degrees to 360 degrees is called one sweep period of the spiral scan, and the period in which the distance signal R(t) of the sweep output repeatedly changes from zero to the maximum value is called one sweep period of the spiral scan. Referred to as one frame, the present invention converts a portion of the number of sweep lines existing in one frame from the beginning of one frame to an integral multiple of 1/2 of the number of scanning lines of the monitor television 8 to the screen of the monitor television 8. It is intended to be displayed.

In other words, one sweep of a spiral scan can be thought of as having two lines above and below the center of the screen, whereas one scan line of a monitor television has only two lines above and below the center of the screen. If the number of sweep lines in one spiral scan frame is N, then if you simply try to display this on the screen of a television monitor, the television monitor will require 2N scanning lines. Therefore, if the number of sweep lines in one spiral scan frame is equal to 1/2 of the scanning line of the monitor television, image information of the spiral scan can be conveniently displayed on the monitor television of the TV scan method. If the number of sweep lines in one frame of spiral scan is more than 1/2 of the number of scan lines of the monitor TV, 1 of spiral scan
In order to display the entire image in a frame on the monitor TV, the number of sweep lines in one frame of the spiral scan is equivalently displayed on the monitor TV using an appropriate means such as the sweep matching device 3 in FIG. It is necessary to perform sweep matching so that the number of scanning lines is 1/2.

Therefore, in the present invention, for example, if three sweeps of the spiral scan are made equivalent to one sweep by the sweep matching device 3, the number of sweep lines in one frame of the spiral scan is equal to the number of scanning lines of the monitor television (( 1/2) x 3 times, and the scanning sonar image can be conveniently displayed on the TV scan monitor.

In FIG. 3, numeral 9 indicates an image of one frame of spiral scan.

Among these, the portion 9-1 has the same number of sweeps as 1/2 of the number of sweeps on the monitor television 8, the portion 9-2 has twice the number, and the number 9-3 has three times the number. The maximum multiple is predetermined based on the design value of the scanning sonar. That is, the sweep matching device 3
can be designed to make any number of spiral scans equivalent to one sweep, not just three sweeps, and how many sweeps to make equivalent to one sweep is determined by scanning sonar in one frame. This is determined by the design condition of how many sweeps it is designed to accommodate. When converting and displaying 9-1+9-2+9-3 on the screen 9 in FIG. 3 on the monitor TV 8, 9-1+9-
By switching between displaying 2 and 9-1, the scanning sonar image can be zoomed and displayed on the monitor television 8.

As an example, a case will be described in which 9-1+9-2+9-3 is converted and displayed.

If one sweep of the spiral scan is divided into 360 parts. A 3-bit digital value obtained by A-D converting the image output A(t) shown in Figure 2 A for the first one sweep period of the spiral scan at each of the 360 division points.
360 items are stored in the first sweep memory 3-1. The sweep memory stores image output A- of the second and third sweep periods following the spiral scan.
Store the D conversion value. As a result, the image outputs of three adjacent spiral scan sweeps are stored in the first sweep memory 3-1.
The computing unit 3-2 sweeps the three image information stored in the first sweep memory 3-1 and outputs it as a sweep output θ(t).
Add for each same angle. The result of the addition is 8 (3 bits) x 3 = 24 levels of image information. Furthermore, the arithmetic unit 3-2 divides the 24 stages of image information into groups of 3 stages and reconfigures it as 3-bit image information.
It is stored in the sweep memory 3-3. Here the first
Sweep memory 3-1 is 3 bits x 360 pieces x 3
This has a storage capacity of 3240 bits, and the second sweep memory 3-3 has a storage capacity of 3 bits x 360 pieces x 1 piece = 1080 bits.
It has a storage capacity of bits. The image information stored in the second sweep memory 3-3 is converted into a television scan format and stored in the video memory 5. Therefore, the sweep matching unit 3 sequentially processes the fourth to sixth sweeps of the spiral scan and sends the output to the video memory 5, thereby creating the area shown by 9-1+9-2+9-3 in FIG. All image information is processed.

Furthermore, the function of the sweep matching device 3 will be explained using FIG. In FIG. 4D, 9 is one frame of the spiral scan screen, 10 is three adjacent bright lines, and 11 is one partial area on the screen. An enlarged view of the partial region 11 is shown in Fig. 4 (e), and in (d) the sweep intervals are sufficiently dense, so three bright lines 1
It looks like one 0, but if you enlarge it, the bright line 10 is made up of three bright lines as shown in Figure 4 (e). The image information of these three bright lines 10 is A-D
The signal is digitized by the converter 2 and stored in the first sweep memory 3-1. The image information of these three bright lines 10 is further processed by the arithmetic unit 3-2.
The image information is stored in the second sweep memory 3-3 as image information corresponding to one bright line information 10' shown in FIG.

Here, the image information stored in the second sweep memory 3-3, that is, the bright line 10' in FIG. 4 is created by combining the three bright lines 10 in FIG. The planar spread of the bright lines 10 is converted into the depth spread (intensity of brightness) of one bright line 10', and compared to extracting one of the three bright lines 10, the original image information is Storage stability is significantly improved. Regarding the quantization of image information A(t) into 8 stages (3 bits), conventional methods
Since the intensity of image information from fish finders, radars, etc. is practically sufficient with eight levels of quantization, this is also a sufficient degree of quantization in the present invention.

The first controller 4 is composed of, for example, a microprocessor or the like, and receives the sweep output of the scanning sonar to generate and supply timing required to each part of the sweep matching device 3. Furthermore, the first controller 4
converts the coordinates of the output of the second sweep memory 3-3 and stores it in the video memory 5. video memory 5
has three layers of memory, and each layer corresponds to the three primary colors of the monitor television 8.

Each bit of 3-bit image information for each sweep stored in the second sweep memory 3-3 is stored corresponding to each layer of the video memory 5 after coordinate transformation.

For example, the LSB of 3-bit information, the second bit,
The logic 1 of the MSB is stored as the logic 1 in the first layer, second layer, and third layer of the corresponding address of the video memory 5, respectively. Next, the coordinate transformation performed when the image information stored in the second sweep memory 3-3 is stored in the video memory 5 will be explained.

Reference numeral 9 in FIG. 5G indicates a spiral scan screen, and reference numeral 12 in FIG. 5C indicates a television scan screen. Here, it is assumed that screen 9 in FIG. 5G is coordinate-transformed and displayed in area 13 in FIG. 5C. It goes without saying that the method of the present invention can be easily applied even when the area 13 is larger than the screen 12. First, one point T on the spiral scan screen 9 can be expressed as one point (γ, θ) on polar coordinates.
On the other hand, TV scan screen 12 corresponding to this point
One point T above can be expressed as one point (x, y) on rectangular coordinates.

Clearly, the relationships x = γ cos θ and y = γ sin θ hold, so if one point T on the television scan screen 12 shown in FIG. x ₀ +γcooθ, −
(y ₀ −γsinθ)}. x ₀ and y ₀ are the distances from the upper left corner of the screen 12 to the center 0 of the area 13, respectively. Therefore, -(y ₀ - γ sin θ) corresponds to the position of the sweep line on the television scan screen 12 where one point T exists, and x ₀ + γ cos θ is the position of the pixel on one sweep line where one point T exists. shows. The image information stored in the video memory 5 is, for example, the screen of a monitor television 8.
Since it is divided into 512 sweep lines x 512 pixels, that is, 262144 pixels, and stored, the image information of one point T is stored at the coordinates {x ₀ + γ coo in the storage position of the video memory 5.
θ, −(y ₀ −γsinθ)}.

The features of the image information thus obtained in the video memory 5 will be explained using FIG. 6. 6th
It is assumed that 9 in FIG. 3 indicates a spiral scan screen and an image 12 is displayed. When the image 12 is enlarged, it is a collection of circular arcs as shown in FIG. This information is sampled every sweep of the spiral scan and sequentially stored in the first sweep memory 3-1.

Therefore, the image stored in the first sweep memory 3-1 is like the black dot in FIG. To simplify the discussion, the first sweep memory 3-1 does not store three sweeps of the spiral scan, but only one sweep, and at the same time, the arithmetic unit 3-2 performs addition operations and grouping. Assume that the stored contents of the first sweep memory 3-1 are simply transferred to the second sweep memory 3-2 without performing any operation. Then, obviously the image stored in the second sweep memory 3-2 also becomes the black dot in FIG. The image obtained in the video memory 5 by coordinate transformation of the black point in FIG. The concentric feature of the image is lost, resulting in an image that looks significantly different from the original image shown in FIG. This tendency becomes more pronounced the closer you get to the periphery of the screen.

In order to overcome this problem, the present invention provides a conversion point at which the spiral scan is converted to a television scan, that is, the sixth point.
A memory that stores the coordinates (video memory addresses) of all pixels within a 0.5 degree sweep of the spiral scan on a concentric circle around each black dot in Figure O, i.e., the bright spot correction memory in Figure 1. 6, for example, when storing a point on the spiral scan on the sweep memory 3-3, ie 13 in FIG. 6, as a television scan point on the video memory 5, the first controller 4 simply uses the coordinate The point obtained by the conversion calculation is not only stored in 14 in Figure 6 O, but also stored in the video memory 5 with reference to the coordinate 14' in Figure 6 stored in the bright spot correction memory corresponding to this point. It is also stored at that address. As a result, 1 point 13 on the spiral scan
are points 14 and 14' on the television scan, and even after the scan system is converted, the characteristics of the spiral scan image as shown in FIG. 6N are not lost.

A specific example of how the image of the coordinates 14' in FIG. 6 is generated will be described below.

One point T on the spiral scan screen 9 can be expressed as one point (γ, θ) on polar coordinates, and one point T on the television scan screen 12 corresponding to this point can be expressed as one point (X, Y) on rectangular coordinates. It can be expressed as Clearly, the relationships X=γcosθ and Y=γsinθ hold.

However, if the distance between scanning lines or one side of a pixel is PC, then other scanning lines are located at a position that is an integral multiple of PC from the central scanning line of the screen. 1 point T on top
is expressed on the actual screen as T ₀ = (, ) with the center of the screen as the reference. Here, is a rounding operator, and γcosθ/PC and γsinθ/PC are rounded off and expressed as integers, indicating the number of pixels in the X direction and Y direction from the center of the screen. That is, T ₀ is the position of the image information expressed in the number of pixels with respect to the center of the actual screen, and corresponds to point 14 in FIG. 6W.

Now, T ₀ = (,
sinθ/PC), T ₀ ′=
{(±2360°), (

±2πα/360°)/PC), and when changing θ in 1° increments, α is a minute change within 0.5°, e.g., α=0.1°, 0.2°, ......, 0.5°, and T ₀ ' is calculated, and when T ₀ ≠ T ₀ ', T 0 ' is stored in the bright spot correction memory 6 corresponding to T ₀ and the video memory 5 corresponding to the position of T _{0 '} is stored. In order to store the same image information as T ₀ in the position,
Coordinate information is sent from the bright spot correction memory 6 to the first controller 4.
Send T ₀ ′. In this way, the image information shown in FIG. 6, 14', is generated.

By doing this, according to the present invention, it is possible to improve the problem in which the characteristics of the radial image become noticeable due to the coordinate transformation from spiral scan to television scan when using only the processing method shown in FIG. This makes it possible to approximate the image display of a spiral scan.

The image information stored in the three-layer storage device of the video memory 5 thus obtained is displayed on the screen of the monitor television 8; Color
Since the image output from the scanning sonar is transmitted in correspondence with each of the three electron guns of the CRT, the image output of the scanning sonar is displayed on the screen of the monitor television 8 in eight colors according to the strength of the image output.

The second controller 7 is for reading the image information stored in the video memory 5 in synchronization with the monitor television 8 and transmitting it to the monitor television 8. It should be noted that if the sweep matching device 3 is used as a high-speed one as the first controller 4, it can be easily realized in the controller 4 as a part of the calculation operation of the controller 4, which is easily considered by the person concerned. It is.

As explained above, according to the present invention, scan conversion can be performed without losing image information even when the number of sweeps in a spiral scan and the number of sweeps in a television scan are different, and zoom conversion can be performed in addition to the ability to perform a zoom conversion even after scan conversion. It has the advantage that the characteristics of the concentric image of the scan are not lost, so when trying to reproduce the image of scanning sonar etc. on the TV screen, it can be faithfully reproduced to the original image, and the reproduced image on the TV screen. It has the advantage that it can now be used for fishing, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Figure 2 is a waveform diagram showing the image output waveform of scanning sonar, Figures 3 and 4 are diagrams showing spiral scan, Figure 5 is a diagram showing orthogonal coordinates, and Figure 6 is from spiral scan to orthogonal coordinates. It is an explanatory diagram in the case of conversion. 2...A-D converter, 3-1...First sweep memory, 3-2...Arithmetic unit, 3-3...Second sweep memory, 4...First controller, 5... Video memory, 6... Bright spot correction memory, 7... Second controller.

Claims (1)

[Claims] 1. After converting the image signal obtained by the spiral scan into a digital value for each fixed angle of the sweep, this is stored in a first sweep memory for at least two sweeps, and then the image signal of each stored sweep is converted into a digital value. The signals are added for each same angle of the sweep and stored in a second sweep memory, and the image information in the second sweep memory is converted into orthogonal coordinates and stored in the video memory, and the image information in the second sweep memory is converted into orthogonal coordinates and stored in the video memory. A scan converter characterized in that spiral scan correction information from a corresponding bright spot correction memory is also stored in a video memory at the same time, and correction is performed by spiral scan. 2. The scan converter according to claim 1, wherein the bright spot correction memory is a memory in which pixels of a certain minute sweep angle of the spiral scan are stored in advance in correspondence with orthogonal coordinates.