JPH01248082A - Image processing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image processing device, and in particular, captures and processes images with depth, such as images of image-tracking flying objects. The present invention relates to an image processing device suitable for use in an image processing system.

(Summary of the Invention) The present invention divides the entire image of the external world into a plurality of split screens, executes binarization processing using an optimal threshold for each split screen, and synthesizes the split binarized images. By obtaining a binarized image of the entire screen, a desired target object can be reliably extracted regardless of the distance of the target object.

(Prior Art) FIG. 3 is a block diagram showing a configuration example of an image processing apparatus using conventional binarization processing.

The conventional device shown in FIG. 3 above includes a frame memory 01 that stores an image of the outside world which is acquired data, and luminance information (distribution status of R degree) of the entire image (full screen data) stored in this frame memory 01. a brightness calculation circuit 02 that calculates
A threshold setting circuit 03 calculates the threshold of the entire image from the luminance information obtained by the luminance calculation circuit 02, and the entire screen is binarized based on the threshold set by the threshold setting circuit 03. It consists of a binarization circuit 04, etc., which outputs a binarized image by setting a threshold value for the entire screen.
The configuration was such that binarization processing was performed based on the threshold value.

(Problem to be solved by the invention) By the way, when processing an image with depth, the above j@
The conventional configuration shown in FIG. 3 has the following problems.

FIG. 4(a) shows, as an image with depth, an image in which horizontal #X (a) is located at the center in the y direction and a ship (b) is present on the horizon.

In such an image, as shown in Fig. 4(b), the brightness contrast in the far distance on the horizon, that is, on line A, is low, and the brightness contrast in the short distance on the bottom of the screen, that is, on line B, is low. The contrast will be higher.

When such an image is binarized using a constant threshold value for the entire screen as in the conventional device described above, the wave crest (C) existing at a short distance is extracted, as shown in Fig. 4(e). , it is not possible to extract only ships (b) that are far away.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image processing device that eliminates such inconveniences and can reliably extract distant targets.

(Means for Solving the Problems) The present invention provides a screen dividing circuit to divide the entire screen to be subjected to binarization processing into a plurality of small screens, and calculates the luminance information of each of the small screens separately. After that, the optimal threshold value is determined for each of the divided small screens, and each small screen is binarized separately. Finally, each binarized screen is synthesized by an image synthesis circuit to obtain one binarized image.

(Function) In the image processing device of the present invention, after the screen is divided by the screen division circuit, luminance information is calculated for each divided screen and a threshold value is set, so that local areas of the screen can be This makes it possible to perform optimal binarization in images, and the image synthesis circuit can restore divided screens into a single binarized screen.

As a result, a desired target object can be reliably extracted regardless of the distance of the target object.

(Example) Hereinafter, an example of an image processing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an apparatus according to an embodiment of the present invention.

Acquired image data (external image) to be subjected to binarization processing
After temporarily storing it in the frame memory 1, the screen division circuit 2
send to The screen division circuit 2 divides the image (
This function sequentially outputs split screen data obtained by dividing the screen) into N parts.
). For example, as a method of screen division, see Figure 2 (
, ), the entire screen is divided by the value in the y direction, and the farthest divided screen is divided into divided screens (1) and divided screens (2).

..., (9) so that the distances become closer in this order.

Then, the screen splitting circuit 2 first sends data regarding the split screen (1) to the brightness information calculation circuit 3, and the threshold setting circuit 4 sets the threshold based on the brightness information (brightness distribution status) obtained. The data of the divided screen (1) is binarized by the binarization circuit 5 based on the threshold value.

Hereinafter, the binarization process is performed similarly for the divided screens (2)...(N).

Finally, the divided binarized images that have been subjected to the split binarization process in the binarization circuit 5 are combined in the image synthesis circuit 6 to obtain one binarized image (full screen).

FIG. 2 is an explanatory diagram for explaining the operation of the above embodiment. b) is the same figure (,
) shows the brightness contrast and level status of each threshold value in line A and line B.

As is clear from Figure 2 (a) and (b), the optimal threshold is set for each split screen and binarization processing is performed, so the target can be accurately identified regardless of the distance. Can be extracted.

Here, let us consider the case where a deep image in which a ship (b) is present on the horizon as shown in the fj42 diagram (a) and FIG. 4 (a) is binarized and the ship (b) is extracted. In such a deep image, the average level of contrast or brightness in the distance (near the horizon, center of the screen) is low, and in the near!
[The average level of contrast or brightness at the bottom of the screen is high (see FIG. 4(b)). In this case, if binarization is performed with a constant threshold value for the entire screen as in the prior art described above, when trying to extract a ship, the wave crest ( ) 1) at the bottom of the screen will also be extracted (see Figure 4). (See (c)), if you try to prevent the wave crest (c) from being extracted, the ship (b) will often not be extracted as well.

Therefore, if configured as in the above embodiment, it is possible to divide the screen (see Figure 2 (a)), obtain luminance information for each divided screen, and set the optimal threshold for each divided screen from the same information. Therefore, the threshold value for distant areas is set low and the threshold value for short distances is set high (see Figure 2 (b)), so it is easy to extract only ships (b). Become.

(Effects of the Invention) As explained above, according to the image processing device of the present invention,
Divide the screen to be binarized into predetermined small screen units, set a threshold based on the brightness information for each split screen, and binarize each corresponding split screen based on the threshold. process,
By performing synthetic restoration, targets that are far away can be reliably extracted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the image processing device according to the present invention, FIG.
FIG. 4 is an explanatory diagram for explaining the operation of the conventional device. 1...7 frame memory, 2...screen division circuit, 3...
...Brightness information calculation circuit, 4...Threshold value setting circuit, 5
... Binarization circuit, 6... Screen composition circuit.

Claims (1)

[Claims] (1) A frame memory that stores images of the outside world, a screen division circuit that divides the images of the outside world stored in the frame memory into multiple screens, and calculates brightness information of the divided screens divided by the screen division circuit. a threshold setting circuit that sets a threshold value for binarization based on the luminance information obtained by the brightness calculation circuit; and a threshold value set by the threshold setting circuit. and an image synthesis circuit that synthesizes and restores the binarized images of the respective split screens that have been binarized by the binarization circuit. An image processing device characterized by: