JPH04182791A - Method for counting object - Google Patents

Abstract

PURPOSE:To improve the accuracy of counting an object by providing plural thresholds with lengths corresponding to projected density values and the number of picture elements. CONSTITUTION:In a first object counting part 3, the number of picture elements on an X-axis equipped with the projection value larger than the threshold of the density is counted from the density projection result prepared by a density projection part 2 and two kinds of the thresholds supplied from a first threshold setting part 4, the number of objects is counted from the threshold corresponding to the number of picture elements, and the counting result is outputted. In a second threshold setting part 8, the threshold with the length corresponding to the projected threshold and the number of picture elements used in the second object counting part 6 is set when the necessity of more counting is decided by a counting result decision part 7. In a counting result indication part 5, the counting results are received from first and second objective counting parts 3 and 6, and these counting values are displayed. Thus, the accurate counting processing can be performed in real time.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention makes it possible to accurately count specific objects in an image in real time using only simple inter-image operations and four arithmetic operations by providing multiple threshold values. Concerning a method for counting objects.

(Prior art) Conventionally, in counting specific objects in an image, the following methods were used: (1) Setting sample points on the image to detect changes in brightness values, and using the difference in density values between the background and the target object at the sample points. The outline of the target object is extracted and the count is performed from that shape.

(2) Divide the image into a plurality of rectangular regions, extract the region of the target object from changes in the density variance of each region, and perform counting based on its shape.

■ Counting is performed by taking the projection of the density value of the image of the target object and measuring the length of the section where the density is above or below a certain value.

A method is provided.

An example of the configuration of an apparatus for implementing the third method is shown in FIG. The number of target objects is counted from the density projection result created by the density projection unit 2 and the fixed threshold set by the threshold setting unit 4, and the counting result is output to the counting result presentation unit 5 for display. There is something I did.

(Problem to be solved by the invention) However, in the methods ① and ② of the prior art described above,
Since complicated processing such as pixel-by-pixel processing and contour extraction is performed, it is difficult to perform target object extraction and counting processing in real time on moving images input from a camera.

Further, in the method (2), since the threshold value of the density value used in the target object counting section 3 is one fixed value, there is a problem that the accuracy of the counting result is not sufficient depending on the density value of the target object.

(Objective of the Invention) It is an object of the present invention to provide an object counting method that can solve the drawbacks of the prior art and perform counting processing with higher accuracy in real time.

(Means for Solving the Problems) In order to solve the above problems and achieve the objects, the present invention provides a method for counting target objects from a projection result obtained by taking a density projection of an image. means for taking a density projection onto the X-axis or the Y-axis or a straight line having an arbitrary slope; means for setting a length threshold according to the projected density value and the number of pixels; and means for taking the density projection. means for counting the number of target objects based on the density projection result created by and the threshold value given from the threshold value setting means;
The counting result determining means outputs a control signal for resetting the threshold to the threshold setting means according to the counting result of the counting means, and the means for presenting the counting result, and the counting result changing means changes the threshold according to the counting result. It is characterized in that it performs counting.

(Function) The present invention counts the number of target objects by using a projected density value and a threshold value of length corresponding to the number of pixels, and counts the number of the next target object according to the counting result. By changing the threshold value and performing counting, it is possible to accurately count and display the number of target objects in real time.

(Embodiment) FIG. 1 is a block diagram of an embodiment showing the configuration of an apparatus for implementing the present invention. In the figure, reference numeral 1 denotes an image input section which outputs an image to be counted or an image obtained by preprocessing this to a density projection section 2.

The density projection unit 2 projects the density of the image input from the image input unit 1 onto the X-axis or Y-axis or a straight line with an arbitrary slope, and projects the density of the image input from the image input unit 1 onto the The density projection results are sent to the target object counting section 6, respectively. In the following explanation, only the case of taking the density projection to the X axis will be explained,
The same applies to the case of density projection onto the Y-axis at an arbitrary inclination.

Here, an example of an image inputted from the image input unit l is shown in FIG. 2. In the figure, 21 indicates a case where no target object is shown, and 22 shows a case where one target object (person) is shown. In case 23, two target objects (people) are shown. In addition, Figure 31.32 is a graph of the results of density projections of each image 21, 22, and 23 in Figure 2 onto the X axis.
．． 33, and the X-axis (7)X in both figures.

X12. ..., X36 are drawn correspondingly.

Returning to FIG. 1, reference numeral 4 denotes a first threshold value setting unit that sets a threshold value for the projected density value and a threshold value for the length of the number of pixels used in the first target object counting unit 3. In addition, the first target object counting section 3 calculates a projection larger than the density threshold based on the density projection result created by the density projection section 2 and two types of thresholds given from the first threshold setting section 4. The number of pixels on the X-axis that have a value is counted, the number of target objects is counted from a threshold of length corresponding to the number of pixels, and the counting result is output.

Reference numeral 7 denotes a counting result determination unit which receives the counting result from the first target object counting unit 3, makes a determination according to the counting result, and sends a control signal to the second threshold value setting unit 8 to set a threshold value. or sends the counting results to the counting result presentation section 5.

The second threshold value setting unit 8 sets the threshold value according to the projected density value threshold and the number of pixels used in the second target object counting unit 6 when the counting result determining unit 7 determines that further counting is necessary. Set the length threshold. The second target object counting section 6 receives the threshold value from the second threshold setting section 8, and performs the same function as the first target object counting section 3 described above.

Further, in the counting result presentation section 5, the first. The counting results from the second target object counting sections 3 and 6 are received and the counted values are displayed.

Hereinafter, the operation of the embodiment shown in FIG. 1 will be explained using the example of the input image shown in FIG. 2 and the graph of the result of density projection onto the X axis shown in FIG. In this embodiment, the first target object counting section 3 determines whether the number is O or 1 or more, and the second target object counting section 6 determines whether the number is 1 or 2.

When an image is input from the image input section 1 to the density projection section 2,
The density projection unit 2 projects the density of the input image onto the X axis. First, the threshold value setting unit 4 sets a density value threshold tl+a length threshold value ri as a threshold value for determining whether the number of target objects is O or 1 or more.

The first target object counting unit 3 calculates the density of the density projection result using the density projection result obtained by the density projection unit 2 and the threshold values t, L, given by the first threshold value setting unit 4. Measure the length of the section on the X-axis that has a density value equal to or greater than the value threshold t1.If the length is less than L1, it is 0 (corresponding to the case of 31), and if it is equal to or greater than L1, it is 0 (corresponding to the case of 32, 33). (corresponding to this case), the count result that is 1 or more is output to the count result determination section 7.

In the counting result determining unit 7, when the result of the first target object counting unit 3 is O (corresponding to the case of 31), that is, when determination is not required again, the counting result presenting unit 5 outputs O.
If the result is 1 or more (corresponding to the cases of 32 and 33), that is, if the determination needs to be made again, the second threshold value setting unit 8 is used to set the threshold value. Send the necessary information. The second threshold value setting section 8
Here, the density value threshold t8. is used as the threshold for determining whether the number of target objects is 1 or 2. A length threshold L8 is set, and the projection result in the density projection section 2 and the thresholds t, L set by the second threshold setting section 8 are set.

Therefore, the second target object counting section 6 counts the target objects.

The second target object counting unit 6 first measures the length of the section on the
If it is less than 1. (corresponding to 32). In the case of L3 or more (corresponding to the case of 33), a count result of 2 is output. The counting result presentation section 5 receives the counting results from the first object counting section 3 and the second object counting section 6 and displays the results.

In this way, the length of the interval at the threshold t1 is significantly different between the case of 0 and the case of 1 or 2, but there is almost no difference between the case of 1 and the case of 2. In terms of length, there is a noticeable difference between cases 1 and 2, but there is almost no difference between cases ○ and 2, so it seems that one threshold cannot distinguish between these three cases. In any case, by using the lengths of both sections of the two threshold values t1 and t as in the present invention, it is possible to distinguish between 0, 1, and 2.

FIG. 4 is a block diagram of another embodiment showing the configuration of an apparatus implementing the present invention, and is an example in which one target object counting section is used repeatedly.

In the figure, reference numeral 1 denotes an image input section, which inputs an image to be counted into a density projection section 2 after background processing and mask processing have been performed on the image. The density projection section 2 takes the density projection of the image input from the image input section 1 onto the X axis, and sends the density projection result to the target object counting section 3.

Reference numeral 4 denotes a threshold setting section for setting a density value threshold and a length threshold used in the target object counting section 3. However, in the initial state, the initial value of the preset threshold value is set, and from the second time onwards, if the counting result determining unit 7 determines that further counting is necessary, the counting result determining unit 7 A threshold value used by the target object counting section 3 is set according to the passed conditions. Furthermore, when the judgment is completed,
A determination end signal is sent from the counting result determining section 7, and the process is terminated. The target object counting unit 3 counts the number of pixels on the X axis that have a projection value larger than the density value threshold based on the density projection result created by the density projection unit 2 and the threshold set by the threshold value setting unit 4. , the number of target objects is counted from the length threshold according to the number of pixels, and the counting result is output.

The counting result determination unit 7 receives the counting results output from the target object counting unit 3, and sends a control signal to the threshold setting unit 4 to set a threshold according to the counting result, or The counting results are sent to the counting result presentation section 5. Further, when it is determined that all counting has been completed, a determination completion signal is sent to the threshold value setting section 4, and the threshold value setting is completed.

The counting result presentation unit 5 displays the numerical value of the counting result output from the counting result determining unit 7.

This embodiment differs from the embodiment shown in FIG. 1 in that there is only one target object counting section 3, and it is used repeatedly as necessary.

The operation of this embodiment will be described below. An image is input from the image input section 1, and the density projection section 2 projects the density of the image obtained from the image input section 1 onto the X axis. here,
The brightness value of the image is used as the density value. Threshold value setting section 4
Now, the darkness value and the length threshold of the density value for making a determination in the target object counting section 3 are set. When the threshold setting section 4 is used for the first time, the initial value is used, and when it is used from the second time onward, the initial value is set. In this case, a threshold value is set based on the information obtained from the counting result determination section 7.

Using the density projection result obtained by the density projection unit 2 and the threshold value given by the threshold value setting unit 4, the target object counting unit 3 calculates the X that has a projection value larger than the density value threshold among the density projection results.
The number of target objects is counted by counting the number of pixels on the axis and the number of target objects from the length threshold according to the number of pixels, and the result is determined by the counting result determination unit 7, and the number of target objects is counted again. If judgment is not necessary, the result is sent to the counting result presentation section 5.
Then, a determination end signal is output to the threshold value setting section 4.

If judgment is necessary again, the information necessary for threshold setting is sent to the threshold setting section 4, the threshold is set again by the threshold setting section 4, and the darkness value set in the target object counting section 3 is again set. and perform the same counting as last time. The counting result presentation unit 5 receives the counting result from the counting result determining unit 7 and displays the result.

The embodiments of the apparatus for carrying out the method of the present invention are not limited to those shown in FIGS. 1 and 4, and the target images are not limited to those shown in FIG. Further, the feature quantities used as density in the density projection unit include all quantities that represent the features of the image. Further, the setting of the threshold value is not limited to the distinction between O and 1 or more, or the distinction between 1 and 2, and includes settings for distinguishing between arbitrary numerical values.

(Effects of the Invention) As explained above, according to the present invention, even when it is difficult to increase the accuracy of counting target objects in real time with conventional techniques, it is possible to easily increase the accuracy of counting target objects by providing multiple threshold values. This is possible using only inter-image calculations and four arithmetic operations, and it is possible to improve the accuracy of counting target objects.

Moreover, the structure of the apparatus for carrying out the method of the present invention is simple, and the cost can be reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment showing the configuration of an apparatus implementing the present invention, Fig. 2 is a diagram showing an example of an input image, and Fig. 3 is a graph of the result of density projection onto the X axis. Figure shown, 4th
FIG. 5 is a block diagram of another embodiment showing the structure of an apparatus implementing the present invention, and FIG. 5 is a diagram showing an example of the structure of a conventional apparatus for counting target objects by density projection. 1... Image input section, 2... Density projection section, 3.
6...Target object counting unit, 4,8...Threshold value setting unit, 5...Counting result presentation unit, 7...Counting result determination unit, 21...Input image (when the number of objects is 0)
, 22... Input image (when the number of objects is 1), 23...
・,・Input image (when the number of objects is 2), 31...X
Concentration projection graph onto the axis (when the number of objects is ○), 32.
・Concentration projection graph to the X axis (when the number of objects is 1),
33... Concentration projection graph onto the X axis (when the number of objects is 2). Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] A method for counting target objects from a projection result obtained by taking a density projection of an image, comprising means for taking a density projection of an input image onto the X-axis or Y-axis or a straight line having an arbitrary slope; A means for setting a length threshold according to the projected density value and the number of pixels, and a density projection result created by the means for taking the density projection and a threshold given by the threshold setting means to determine the number of target objects. The counting means is comprised of a counting means, a counting result determining means for outputting a control signal for resetting the threshold to the threshold setting means according to the counting result of the counting means, and a means for presenting the counting result, and according to the counting result. An object counting method characterized in that counting is performed by changing a threshold value.