JPH04299783A - Circuit and method for binarizing video signal - Google Patents

Abstract

PURPOSE:To binarize video signals without being affected by the fluctuation and selection of a slice level concerning the video signal binarizing circuit and method. CONSTITUTION:A video differentiated signal s2 is generated by differentiating an analog video signal s1 and it is held as memory that the video differentiated signal s2 is turned to a first positive or negative prescribed value level. When the video differentiated signal s2 is turned to a second prescribed value level having a positive/negative code different from the first prescribed value, the memory is canceled and a binary signal s3 is outputted corresponding to the state of holding or canceling the memory.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal binarization circuit and a binarization method, and more particularly, the present invention relates to a video signal binarization circuit and a binarization method that process video information regarding the pattern shape of an object. This is useful for so-called pattern recognition.

Binarizing a video signal, which is an analog signal, is performed by comparing the video signal with a threshold value via a voltage comparator. In this case, for example, the necessary binarization is performed by setting the video signal above the threshold to "1", that is, black (or white), and the signal below the threshold to "0", that is, white (or black). be exposed. This threshold is generally called the slice level.

However, the voltage level of the video signal regarding the pattern shape of the object is not determined simply by the shading of the pattern shape of the object, but also depends on the conditions at that time, such as the brightness and darkness of the object itself, the lighting conditions, etc. Furthermore, it is known that satisfactory pattern recognition cannot be achieved if the slice level is set to a fixed value, since it also varies depending on the type of sensor used for pattern recognition. For this reason, as a method for adapting this slice level to an incoming video signal, for example, a selective fixed binarization method or a floating threshold method is generally employed.

0004

[Prior Art] Regarding the conventional binarization method, Fig. 4(a),
This will be explained with reference to (b). In the case of the selective binarization method shown in FIG. This method uses trial and error to determine whether or not the binary signal obtained is appropriate. In the case of this method, the analysis tree is devised in various ways to minimize the number of selections, and has the advantage of obtaining extremely clear images, but the analysis software is complex and the time required for binarization is also high. It has the disadvantage of being long.

In the case of the floating binarization method shown in FIG. 4(b), by averaging the maximum and minimum values of the video signal sent and selecting this as the slice level, the video signal is This is a method in which the slice level is varied each time according to the voltage level. Although this method is simple in terms of software, it has the disadvantage that the circuit configuration is relatively complex.

[0006]

[Problems to be Solved by the Invention] In the case of the conventional video signal binarization method described above, an appropriate slice level is obtained by selecting from a plurality of slice levels or by varying the slice level. The slice level is determined depending on the voltage level of.

Unlike the conventional video signal binarization method described above, the present invention can obtain a binary signal without selecting or varying the slice level and without depending on the voltage level of the video signal itself. An object of the present invention is to provide a video signal binarization circuit and a binarization method using a new and relatively simple system.

[0008]

[Means for Accomplishing the Object] FIG. 1 is a diagram showing the principle of the present invention. In the figure, 1 is a video signal differentiating circuit, 2 is a signal change storage means, 3 is a memory release means, and 4 is an output means.

In order to achieve the above object, the video signal binarization circuit of the present invention receives an analog video signal (s1) and converts the differential signal (s2) of the analog video signal, as shown in FIG. A video signal differentiating circuit (1) to output, a signal change storage means (2) for storing as a memory that the differential signal (s2) has reached a first predetermined positive or negative value level, and the differential signal (s2). ) reaches a second predetermined value level with a sign different from the first predetermined value, a memory canceling means (3) for canceling the memory, and a binary signal ( s3).

Further, the video signal binarization method of the present invention differentiates an analog video signal (s1) to produce a video differential signal (s2).
is generated, and holds as a memory that the video differential signal (s2) has reached a positive or negative first predetermined value level, and the video differential signal (s2) has a positive or negative value different from the first predetermined value. It is characterized in that when the second predetermined value level having a sign is reached, the storage is canceled and a binary signal (s3) corresponding to the holding state or the cancellation state of the storage is output.

[0011]

[Operation] In the present invention, the transmitted video signal is first differentiated, and a change pulse is generated from the level change of the video signal corresponding to the transition from bright to dark or dark to bright in the pattern of the object. The positive and negative change pulses are used to memorize or cancel the level change of the video signal, respectively, and output this held or canceled state as a binary signal. This binarization method makes it possible to recognize the target pattern without selecting or varying the slice level. The operation of the present invention will be further explained with reference to FIG.

In FIG. 2, (a) is an explanatory diagram showing a state in which a sensor scans a pattern of an object of a video signal;
b) to (d) respectively show signal waveform diagrams regarding video signals generated through sensor scanning according to figure (a). Figure (b) shows the conditions for binarization, for example, when the lighting condition is good, and similarly, (c) shows the case when the lighting is too dark, and (d) shows the case when the lighting is too bright. It shows. In addition, in each figure, from top to bottom of the drawing, the video analog signal (s1), the binarized output when the slice level is fixed (s4), the differential signal in the present invention (s2), the present invention The binarized output (s3) in FIG.

As can be easily understood from FIG. 2, when the lighting conditions are good, the video signal s1 can be binarized as is, but when it is too dark or bright, the slice level is fixed. Binarization is not possible in this case. However, according to the binarization method of the present invention, a differential signal s2 is generated from the video signal s1, and a change pulse P1 of this differential signal s2 is generated.
, P2, for example, remembers and cancels the transition from bright to dark. By setting the holding state of this memory to, for example, "1" and the release state to "0", a binary signal can be obtained and binarization can be easily performed. In addition, it is desirable that the voltage level change from bright to dark or from dark to bright in the video signal is sudden, and when the subject of the video signal is monochrome, this level change is particularly steep, so binarization is is carried out well.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a circuit diagram of a video signal binarization circuit according to an embodiment of the present invention, and schematic diagrams of signal waveforms of each part are added to the figure. In the figure, this video signal binarization circuit includes a first operational amplifier A forming an input section,
A video signal differentiating circuit (CR circuit) B disposed next to the first operational amplifier A and generating a differential signal s2;
A reference voltage VR1 is arranged at the next stage of the differentiating circuit B and defines the slice level for the changing pulse of the differentiated signal.
(positive voltage), VR2 (negative voltage) are input to each inverting terminal, and the output signal from the video signal differentiation circuit B is input to each non-inverting terminal, respectively.
The inverter E placed next to the third operational amplifier D and the second operational amplifier C generate
1", is reset to "0" again by the output signal of the inverter E, and is composed of a flip-flop circuit F whose output is the output signal of this video signal binarization circuit.

In the circuit of the above embodiment, the video signal s1 is
The signal is input to the first operational amplifier A, is amplified, becomes an amplified signal s1', and is input to the video signal differentiation circuit B forming the CR circuit. In this differentiating circuit B, first, the amplified signal s
A positive transition pulse P1 corresponding to the rising edge of 1' is generated, and a negative transition pulse P2 corresponding to the falling edge of the video signal is generated.

The second operational amplifier C detects that the positive change pulse P1 is equal to or higher than the positive reference voltage VR1, and generates a first one-shot pulse P1'. Further, in the third operational amplifier D, the negative change pulse P2 is compared with the negative reference voltage VR2, and a negative rectangular pulse P2' is similarly generated, and this negative rectangular pulse P2' is inverted in the inverter E. A second one-shot pulse P2'' is formed.The flip-flop circuit F is set by the first one-shot pulse P1' and detects that the target pattern of the video signal changes from bright to dark, and also stores this. However, it is reset by the second one-shot pulse P2'', and upon detecting that the target pattern has changed from dark to bright, the memory is canceled. The output of flip-flop F is output as a binary signal s3.

The video signal binarization circuit of the above embodiment employs a video signal differentiating circuit and a storage circuit, and detects a level change of the video signal and stores this level change to perform the necessary video signal binarization. I'm getting a signal. Therefore, unlike the conventional method, there is no need to select or vary the slice level, which enables a relatively simple circuit configuration.
It also eliminated the need for complex analysis software.

In the above embodiment, as an example, the state before the first change pulse is generated is described as bright, but the state before the first change pulse is generated may also be considered dark. , can be selected according to the pattern of the object.

[0019]

[Effects of the Invention] As explained above, according to the present invention,
It is possible to binarize a predetermined video signal without selecting or varying the slice level, and this has the remarkable effect of providing a new video signal binarization circuit and binarization method.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is an explanatory diagram of the operation of the binarization method of the present invention.

FIG. 3 is a circuit and signal explanatory diagram of a video signal binarization circuit according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional video signal binarization method.

[Explanation of symbols]

s1 Video signal s2 Differential signal s3 Binary signal 1 Video signal differentiator circuit 2
Signal change storage means 3 Memory release means 4 Output means A, C, D Operation amplifier B
Differential circuit E inverter

Claims (2)

[Claims] 1. A video signal differentiating circuit (1) that receives an analog video signal (s1) and outputs a differential signal (s2) of the analog video signal; a signal change storage means (2) for storing as a memory the fact that the differential signal (s2) has reached a predetermined value level; A memory canceling means (3) for canceling the memory, and a binary signal (3) corresponding to the retention state or release state of the memory.
s3). 2. Differentiating an analog video signal (s1) to generate a video differential signal (s2), and storing that the video differential signal (s2) has reached a positive or negative first predetermined value level. holding the video differential signal (s2), and canceling the storage when the video differential signal (s2) reaches a second predetermined value level having a sign different from the first predetermined value, and returning the storage to the holding state or release state. A video signal binarization method characterized by outputting a corresponding binary signal (s3).