KR101927957B1 - A luminance revision method of camera image and program thereof - Google Patents

Abstract

According to an embodiment of the present invention, there is provided a luminance correction method for a camera-captured image, comprising: obtaining an image of an imaging region using a camera; Loading the image and displaying the image on a display unit; Loading a preset calibration guide circle into the display unit; And correcting the luminance of the image by reflecting the correction value designated in the correction guide circle with respect to the image, wherein the luminance value of the image increases as the luminance value increases toward the center region and increases radially toward the center region, The correction guide circles are divided into a plurality of sections by a plurality of concentric circles having a larger radius around the center point and the same correction value is designated in the same section between adjacent concentric circles, The correction value is set differently as the center point moves away from the center. In the step of correcting the brightness, brightness correction is performed for each section of the correction guide circle with respect to the image.

Description

TECHNICAL FIELD [0001] The present invention relates to a brightness correction method and a program for a camera-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brightness correction method and a program for a camera-captured image, and more particularly, to a brightness correction method and a program that can perform brightness correction of an image for each section of a correction guide circle with respect to an image.

The thermal imaging camera measures the temperature distribution detected in the object and provides a thermal image. The user can visually observe the heat dissipation or thermal characteristics in the monitored area using an infrared camera and monitor a specific heat generation event. An infrared image is created by measuring the temperature change of a target object or scene with an infrared camera and converting it into a real image. The main components of the infrared camera include a lens, a focal plane array (FPA) detector, a detector cooling device according to the model, and an electronic device for processing and displaying images.

However, an image obtained by using an infrared camera necessarily has an error caused by vignetting. In other words, the amount of light corresponding to the entire diameter area of the lens is incident on the center of the screen, but the edge of the screen is reduced in the amount of light depending on the lens configuration, so that the edge or periphery of the image formed on the lens appears darker than the center. In an infrared camera that measures the temperature of a target object with the brightness of infrared rays radiated from the target object, the edge of the screen is slightly darkened in the general visual image, The temperature is lowered. In other words, the luminance of the central region is measured to be high and the temperature is calculated to be low, and the luminance of the peripheral region is measured to be low, so that the temperature of the object is distorted.

Accordingly, it is necessary to correct the distorted luminance with respect to the acquired image. The luminance correction according to the conventional method is performed for each pixel constituting the image. That is, a method of correcting the luminance value for each pixel by calculating different correction values for the luminance values of each pixel. However, in order to perform the NUC (Uniformity Correction) for each pixel, the computation speed is slowed down to such a degree that it becomes a practical obstacle.

The present invention improves the conventional luminance correction method, and proposes a more advanced luminance correction method which is simpler and reduces the amount of correction calculation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to solve the above problems by providing a method of correcting luminance of each pixel in an image by applying a single correction value to pixels of a predetermined section A brightness correction method and a program capable of simplifying a brightness correction operation by correcting brightness and performing such a correction method for each section.

However, the object of the present invention is not limited to the above, and other objects of the present invention are to be understood by those skilled in the art to which the present invention belongs It will be possible.

According to another aspect of the present invention, there is provided a brightness correction method for a camera-captured image, comprising: obtaining an image of an imaging area using a camera; Loading the image and displaying the image on a display unit; Loading a preset calibration guide circle into the display unit; And correcting the luminance of the image by reflecting the correction value designated in the correction guide circle with respect to the image, wherein the luminance value of the image increases as the luminance value increases toward the center region and increases radially toward the center region, The correction guide circles are divided into a plurality of sections by a plurality of concentric circles having a larger radius around the center point and the same correction value is designated in the same section between adjacent concentric circles, The correction value is set differently as the center point moves away from the center. In the step of correcting the brightness, brightness correction is performed for each section of the correction guide circle with respect to the image.

The size or position of the correction guide circle may be adjusted based on the center area of the image and the center point of the correction guide circle so that the correction guide circle fits the image before the step of correcting the luminance of the image. The method further comprising the steps of:

The step of correcting the brightness may include: calculating a brightness value for each pixel of the image; Designating a correction value for each section of the correction guide circle; And correcting brightness of an image for each section by multiplying a representative brightness value of an image positioned in each section of the correction guide circle by a correction value of the corresponding section.

The correction value of each section may be calculated by dividing the luminance value of the center point of the image by the representative luminance value of the image located in the corresponding interval.

According to another aspect of the present invention, there is provided a computer-readable recording medium having a computer-readable program recorded thereon for correcting a brightness of a camera-sensed image according to an embodiment of the present invention.

According to the brightness correction method and program for a camera-captured image according to the embodiment of the present invention, brightness correction of an image is performed for each section of a correction guide circle with respect to an image, thereby simplifying the brightness correction calculation.

However, the effects of the present invention are not limited to those described above, and other effects of the present invention can be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

FIG. 1 is a flowchart illustrating a luminance correction method of a camera-captured image according to an exemplary embodiment of the present invention.
2 is a diagram exemplarily showing an image of an imaging region in which a vignetting phenomenon is reflected.
3 is a view showing a correction guide circle according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unnecessary. The terms described below are defined in consideration of the structure, role and function of the present invention, and may be changed according to the intention of the user, the intention of the operator, or the custom.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art to which the present invention pertains, It is only defined by the scope of the claims. Therefore, the definition should be based on the contents throughout this specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

METHOD FOR CORRECTING BRIGHTNESS OF A CAMERA

FIG. 1 is a flowchart illustrating a luminance correction method of a camera-captured image according to an exemplary embodiment of the present invention.

A method of correcting brightness of a camera-sensed image according to an embodiment of the present invention includes the steps of acquiring an image of an image sensing area using a camera (S1), loading the image and displaying the image on a display unit (S2) (S3) of loading the guide circle on the display unit, and correcting the brightness of the image by reflecting the correction value assigned to the correction guide circle with respect to the image (S4).

First, the image of the sensing region reflects a vignetting phenomenon having a luminance distribution in which the luminance value decreases toward the center region and decreases as the distance from the central region increases radially. As shown in FIG. 2, the luminance distribution shown in the photographed image decreases radially as the distance from the center of the image radially decreases, and the luminance distribution gradually decreases to show a concentric circle pattern. According to the acquired image, it can be considered that the pixels located on the same radius in the virtual center point (i.e., Zone 0) have substantially the same luminance value (or a luminance value within a certain category). The present invention uses a luminance variation pattern that draws a concentric circle, as described later.

Next, the acquired image of the imaging area is displayed on the display unit, and the correction guide circle is loaded on the display unit and displayed. 3 is a view showing a correction guide circle according to an embodiment of the present invention. As shown in the figure, the correction guide circles are divided into a plurality of sections by a plurality of concentric circles having a larger radius around the center point. The same correction value is assigned to a section between a concentric circle and its adjacent concentric circle (annular area), and the correction value can be set differently for each section. The correction value assigned to each section is different from the center point It can be set to zero.

Next, the brightness of the image is corrected by reflecting the correction value assigned to the correction guide circle with respect to the image. As described above, in the image, there is a characteristic that the brightness variation pattern appears in the form of a concentric circle, and the correction guide circle is also set in the form of a plurality of concentric circles having a larger radius. It is done by section. That is, the area of the image corresponding to one section of the correction guide circle will be an annular band shape, and the area is uniformly subjected to the luminance correction by the correction value specified in the corresponding section of the correction guide circle. This configuration provides an advantage of greatly simplifying the luminance correction calculation as compared with the conventional luminance correction method in which a correction value is specified for each pixel of an image and luminance correction is performed for each pixel.

More specifically, the step of correcting the brightness includes the steps of (a) calculating a brightness value for each pixel of the image, (b) designating a correction value for each section of the correction guide circle, and (c) And correcting the luminance of the image for each section by multiplying the representative luminance value of the image located in each section of the circle by the correction value of the corresponding section.

In the step (b), the correction value of each section is calculated by the following equation (1).

Equation 1

Correction value (X) = luminance value of Zone 0 (A) / representative luminance value of zone to be measured (B)

In this case, 'Zone 0' refers to the pixel at the center of the image, the luminance value (A) of Zone 0 is the luminance value of the pixel at the center point, and the representative luminance value (B) Refers to the luminance value of the pixel at the center point.

The method further includes a step of adjusting the size or position of the correction guide circle based on the center area of the image and the center point of the correction guide circle so that the correction guide circle fits the image before the step of correcting the brightness of the image can do. First, the center point of the correction guide circle is aligned with the center point of the image. The width of the brightness change of the brightness generated in the image changes depending on the type and arrangement of the lenses employed in the infrared camera. Therefore, after the center point is matched with the center point of the image, the size of the correction guide circle And adjusts to expand / contract.

A program stored in the recording medium

Meanwhile, a method for correcting brightness of a camera-sensed image according to an embodiment of the present invention may be implemented by a computer program including instructions executable by a computer. A computer program includes programmable machine instructions that are processed by a processor and may be implemented in a high level programming language, an object-oriented programming language, an assembly language, or a machine language. In addition, the computer program may be recorded on a computer readable recording medium of a type (e.g., memory, hard disk, magnetic / optical medium or solid-state drive).

Therefore, the luminance correction method of the camera-sensed image according to the embodiment of the present invention can be realized by the computer program as described above being executed by the computing device. The computing device may include a processor, a memory, a storage device, a high-speed interface connected to the memory and a high-speed expansion port, and a low-speed interface connected to the low-speed bus and the storage device. Each of these components is connected to each other using a variety of buses and can be mounted on a common motherboard or mounted in any other suitable manner.

Where the processor may process instructions within the computing device, such as to display graphical information to provide a graphical user interface (GUI) on an external input, output device, such as a display connected to a high speed interface And commands stored in memory or storage devices. As another example, multiple processors and / or multiple busses may be used with multiple memory and memory types as appropriate. The processor may also be implemented as a chipset comprised of chips comprising multiple independent analog and / or digital processors.

The memory also stores information within the computing device. In one example, the memory may comprise volatile memory units or a collection thereof. In another example, the memory may be comprised of non-volatile memory units or a collection thereof. The memory may also be another type of computer readable medium such as, for example, magnetic or optical disk.

And, the storage device can provide a large amount of storage space to the computing device. The storage device may be a computer readable medium or a configuration including such a medium and may include, for example, devices in a SAN (Storage Area Network) or other configurations, and may be a floppy disk device, a hard disk device, A tape device, a flash memory, or other similar semiconductor memory device or device array.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention is not limited thereto and that various changes and modifications may be made therein without departing from the scope of the invention.

Claims (5)

Acquiring an image of an imaging region using a camera;
Loading the image and displaying the image on a display unit;
Loading a preset calibration guide circle into the display unit; And
Correcting brightness of the image by reflecting a correction value assigned to the correction guide circle with respect to the image;
Lt; / RTI >
The brightness value of the image increases as it goes toward the central region and decreases as the brightness increases radially from the central region,
Wherein the correction guide circles are divided into a plurality of sections by a plurality of concentric circles having a larger radius around the center point and the same correction value is designated in the same section between adjacent concentric circles, The more distant from the center,
The brightness correction is performed for each section of the correction guide circle with respect to the image,
Adjusting the size or position of the correction guide circle based on the center area of the image and the center point of the correction guide circle so that the correction guide circle fits the image before the step of correcting the brightness of the image ; ≪ / RTI >
Wherein the step of correcting the luminance comprises:
Calculating a luminance value for each pixel of the image;
Designating a correction value for each section of the correction guide circle; And
Multiplying a representative brightness value of an image positioned in each section of the correction guide circle by a correction value of the corresponding section to correct brightness of the image for each section;
≪ / RTI >
A method for correcting luminance of a camera image. delete delete The method according to claim 1,
Wherein the correction value of each interval is calculated by dividing the luminance value of the center point of the image by the representative luminance value of the image positioned in the corresponding interval. A program stored in a computer-readable recording medium on which a computer program executed by the method of any one of claims 1 to 4 is recorded.

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