JPH10334211A - Method and system for eliminating glitter in image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image from which a glittered part due to lighting is eliminated by lighting an object from plural directions so as to obtain images corresponding to each lighting direction and selecting pixels with darkest density among pixels at the same position thereby configuring one image. SOLUTION: An image pickup device 4 picks up one image for each lighting direction and four images converted into digital signals by an A/D converter 11 are stored sequentially to a 1st memory 13a - a 4th memory 13d by a changeover device 12. A personal computer 14 reads pixels at the same position of the images from the memories 13a-13d and selects a pixel with a lowest density. The selection is applied to all pixels of the images and the selected pixels are used to configure one image pattern, which is used for a selected image. The image is converted into analog data by a D/A converter 16 and displayed on a monitor 16. A glittered part appears in the images stored in the memories 13a-13d whose number is the same as the number of lighting directions, but the selected image processed by the personal computer 14 is configured with lighted pixels not causing glitter so as to eliminate the effect of glitter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and an apparatus for removing gloss partially occurring in an image captured according to the angle and position of illumination.

[0002]

2. Description of the Related Art In an image picked up by an image pickup device such as a television camera while illuminating a subject, a portion which reflects illumination light depending on the direction of illumination appears as a glossy portion. FIG. 6 shows a glossy portion that appears on a subject by illumination. When the illumination device 2 illuminates, for example, a spherical object 1 as a subject, a glossy portion 3 brighter than the surroundings appears in a substantially front portion. If such a glossy portion 3 appears, a correct image of the subject 1 cannot be obtained.

[0003]

In order to prevent such a glossy portion from being generated in a subject, a lighting method has been devised so that light beams which are regularly reflected do not enter the image pickup apparatus.
Setting up this lighting device took a considerable amount of time. There is also a method of reducing a glossy portion of an image in which a glossy portion occurs in a subject by a method such as density averaging.
There has been a problem that the image of the image changes due to a change in the overall density.

The present invention has been made in view of the above problems, and has as its object to provide a method and an apparatus for removing a glossy portion from an image having a glossy portion.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, an image pickup device is arranged to face a subject, and illumination is performed from a plurality of illumination directions. An image is taken and stored for each illumination, and the darkest pixel is selected by comparing the densities of the pixels at the same position in the obtained image for each illumination, and one screen is constituted by the selected pixels.

[0006] The position of the glossy portion generated on the subject changes depending on the irradiation direction of the illumination device. For this reason, glossy portions occur in different portions in an image captured from each direction while changing the illumination direction. The density of the pixels at the same position in all the obtained images is compared, and the pixel having the darkest density is selected to constitute one image as the pixel at that position. Represent.

According to the second aspect of the present invention, an image pickup device is arranged to face a subject, illumination is performed from N illumination directions, and a first image captured from a first illumination direction is stored in a first memory. And the second image captured from the second illumination direction is stored in the second memory, and the darker pixel is selected by comparing the densities of the pixels at the same position in both images. 1
Composing a selected image, overwriting it in a first memory, overwriting a third image taken from a third illumination direction in a second memory,
The density of pixels at the same position in the first selected image and the third image is compared, the darker pixel is selected, the second selected image is composed of the selected pixels, and this is overwritten in the first memory. The fourth image captured from the illumination direction of 4 is overwritten in the second memory, the density of the pixel at the same position of the second selected image and the fourth image is compared, and the darker pixel is selected and selected. Construct a third selected image and overwrite it in the first memory;
(1) Obtain a selected image.

First, images in illumination directions illuminated from two different directions are stored in a first memory and a second memory, respectively, and the same pixel of both images is compared to select a pixel having a darker density to obtain a first image. A selected image is constructed and overwritten in the first memory. Next, the image from another illumination direction is overwritten on the second memory, the density of the pixel at the same position of the first selected image is compared, and the pixel with the darker density is selected to form the second selected image. Overwrite memory. The (N-1) th selected image thus obtained is a screen from which gloss has been almost removed. According to the present invention, even when N images are obtained by illuminating from N directions, an image with almost no gloss can be obtained if there are two memories.

According to a third aspect of the present invention, there is provided an imaging device arranged to face a subject, an illuminating device for illuminating the subject from a plurality of directions, and respective memories for storing images taken for each direction of illumination. Image selecting means for comparing the densities of pixels at the same position in the image for each illumination direction, selecting the darkest pixel, and forming one screen with the selected pixel.

A subject is illuminated from a plurality of directions by an illuminating device, and an image is taken by an imaging device for each direction and stored in separate memories. The image selection means compares the densities of the pixels at the same position of the image stored in each memory, selects the pixel having the darkest density, and configures one screen with the selected pixels. This screen is a screen from which gloss has been removed.

According to a fourth aspect of the present invention, there is provided an imaging device arranged to face a subject, an illumination device for illuminating the subject from N illumination directions, and a first memory for storing an image taken by the imaging device. And a second memory, the first image captured from the first illumination direction is stored in the first memory, the second image captured from the second illumination direction is stored in the second memory, and the two images are stored at the same position. The darker pixel is selected by comparing the pixel densities, a first selected image is composed of the selected pixel, this is overwritten in the first memory, and the third image captured from the third illumination direction is obtained. The second memory is overwritten, the density of the pixels at the same position in the first selected image and the third image is compared, the darker pixel is selected, and the second selected image is constituted by the selected pixels. Overwrites one memory and stores a fourth image captured from a fourth illumination direction in a second memory. Then, the density of the pixels at the same position in the second selected image and the fourth image is compared, the darker pixel is selected and the third selected image is composed of the selected pixels, and this is overwritten in the first memory. And an image selecting means for obtaining the (N-1) th selected image in the same manner.

The illuminating device first illuminates the subject from two different directions, and stores images captured by the imaging device for each illumination direction in the first memory and the second memory, respectively. The image selection means compares the same pixels of both images and selects the darker pixel to form a first selected image, and overwrites this in the first memory. Next, the image is illuminated by the illumination device from another illumination direction, and the image captured by the imaging device is overwritten in the second memory. The image selecting means compares the densities of pixels at the same position in the image read from the second memory and the first selected image, and selects a pixel having a darker density to form a second selected image.
Overwrite memory. In this manner, the (N-1) th selected image can be obtained, and this image is an image from which gloss has been almost removed. According to the present invention, even in the case where N images are obtained by illuminating from N directions, if there are two memories, it is possible to obtain an image (N-1th selected image) from which gloss is almost eliminated.

In the invention of claim 5, the number of the illuminating device is one, and the illuminating device moves in each illuminating direction to perform the illuminating.

By illuminating the subject from a plurality of illumination directions by moving the illumination device, a single illumination device can capture a plurality of images having different illumination directions. For example, in order to illuminate a subject flowing on a belt conveyor with a lighting device in a plurality of directions and obtain a screen in each direction, providing a lighting device in each direction enables quick imaging. .

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the imaging device and the illumination direction of the present embodiment. In the present embodiment, for example, 4
Illumination from two directions will be described. In the present invention, it is only necessary to use two or more directions. As the illumination source, for example, a fluorescent lamp or a halogen lamp is used. The subject 1 is shown as a sphere, but may have any shape.
(A) shows a side view, in which an imaging device 4 such as a television camera is arranged on the horizontal line so as to face the subject 1, two illumination devices 2 are arranged at an angle of α1 from above, and at an angle of α2 from below. Two lighting devices are arranged. (B) shows a plan view,
The upper and lower two illuminating devices 2 are arranged at an angle β1 to the right as viewed from the imaging device 4 in the figure, and the other two upper and lower illuminating devices 2 are arranged at an angle β2 to the left. In addition, 4
Although the lighting devices 2 are arranged in the four directions, one lighting device 2 may be moved in the four directions.

FIG. 2 shows an image taken in the illumination direction shown in FIG. 1 and an image obtained by removing a glossy portion from this image according to the present embodiment. (A) to (D) show images respectively illuminated from four directions. In each case, a glossy portion 3 appears. (E) shows an image of the subject 1 from which the glossy portion 3 has been removed by the method of the present invention.

FIG. 3 is a block diagram showing the configuration of the first embodiment of the present invention. Subject 1, lighting device 2, and imaging device 4
Are arranged as shown in FIG. The imaging device 4 captures one image for each illumination direction. This image is converted from an analog signal into a digital signal by the A / D converter 11, and four images for each illumination direction are sequentially stored in the first memory 13 a to the fourth memory 13 d by the switching device 12.
The personal computer 14 controls the memory switching, reads out the pixels at the same position of the image from the memories 13a to 13d, and selects the pixel having the lowest density (dark, that is, close to black). This selection is made for all the pixels of the image, and one screen is constituted by the selected pixels, and this is called a selected image. The selected image is converted from digital to analog data by the D / A converter 15 and displayed on the screen of the monitor 16. In the case of this embodiment, the same number of memories 13a to 13d as the illumination directions are required. Each memory 13a-1
The image stored in 3d shows the glossy portion 3 as shown in FIGS. 2A to 2D, but the selected image processed by the personal computer 14 is shown in FIG. Illuminated portions that do not produce gloss. Thereby, the influence of gloss can be eliminated.

FIG. 4 shows a modification of FIG. That is, FIG.
Is replaced by an arithmetic processing comparator 17 and a final memory 18 for storing a final image (selected image). The function of the personal computer 14 shown in FIG. 3 is to compare the pixels at the same position in the four images, select one of them, configure the selected image with the selected pixels, and store it in the memory. It is one that is taken out and configured.

FIG. 5 shows a second embodiment of the present invention. First
In the embodiment, the same number of memories as the number of illumination directions are required. However, in this embodiment, two memories may be used regardless of the number of illumination directions. The device shown in FIG. 5 is different from the hardware in that the memories are a first memory 13a and a second memory 13b.

The processing by the personal computer 14 of this embodiment is performed as follows. It is assumed that there are four illuminating devices 2 that illuminate from four directions. Note that one lighting device 2 may be moved to illuminate from four directions.
First, the subject 1 is illuminated from one direction and is captured by the imaging device 4, and the image is stored in the first memory 13a.
Similarly, an image obtained by illuminating from the second direction is stored in the second memory 13b. Next, the same pixel of both images is compared to select a pixel having a darker density. Pixel selection is performed for all the pixels of both images in this manner, an image composed of the selected pixels is set as a first selected image, and this is overwritten in the first memory 13a. Next, the image is illuminated from the third illumination direction, and the image captured by the imaging device 4 is overwritten in the second memory 13b. The image read out from the second memory 13b and the density of the pixel at the same position of the first selected image are compared, and the pixel with the darker density is selected to form the second selected image and overwrite the first memory 13a. Next, the image is illuminated from the fourth illumination direction, and the image captured by the imaging device 4 is overwritten on the second memory 13b. The image read out from the second memory 13b and the density of the pixel at the same position of the second selected image are compared, and the pixel with the darker density is selected to form the third selected image and overwritten on the first memory 13a. This third selected image is substantially the same as the image of FIG. 2E, and is an image composed of a normal illumination portion after removing the glossy portion. It should be noted that the personal computer 14 of the present apparatus can be replaced with the arithmetic processing comparator 17 and the final memory 18 shown in FIG.

Although the above description has been made on the assumption that the object is a still image, the object may be a moving object running on a belt conveyor or the like. In that case, the illumination switching time may be shortened with respect to the moving speed of the object, and the object may be photographed at almost the same position. Further, even when the target object is moving, a plurality of imaging devices and a plurality of lighting devices may be used as long as the relative relationship between the target object and the imaging device is the same.

[0022]

As is apparent from the above description, according to the present invention, the subject is illuminated from a plurality of directions, images are obtained from each of the illumination directions, and pixels at the same positions are compared with each other. By selecting a dark pixel and forming one image (selected image) with the selected pixel, an image from which a glossy portion due to illumination has been removed can be obtained. Also, a first selected image is formed from images in two illumination directions, a second selected image is formed from this first selected image and an image in the next illumination direction, and so on. By doing
Even in the case of the N-direction illumination direction, a selected image can be obtained with two memories. This selected image is an image from which gloss caused by illumination has been removed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical arrangement according to an embodiment of the present invention;
(A) is a side view, (B) is a plan view.

FIG. 2 is an image (A) to which images are taken in the illumination direction of FIG. 1;
It is a figure which shows (D) and the image (E) which removed the glossy part by this invention.

FIG. 3 is a diagram showing a configuration of the first embodiment.

FIG. 4 is a diagram showing a modification of the first embodiment.

FIG. 5 is a diagram illustrating a configuration of a second embodiment.

FIG. 6 is a diagram showing a glossy portion generated on a subject by illumination.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Subject 2 Illumination device 3 Glossy part 4 Imaging device 11 A / D converter 12 Switching device 13a-13d 1st memory-4th memory 14 Personal computer 15 D / A converter 16 Monitor 17 Arithmetic processing comparator 18 Final memory

Claims (5)

[Claims] 1. An image pickup device is arranged to face a subject, illumination is performed from a plurality of illumination directions, an image is captured and stored for each illumination from each illumination direction, and an obtained image for each illumination direction is obtained. Wherein the darkest pixel is selected by comparing the densities of the pixels at the same position, and one screen is constituted by the selected pixels. 2. An image pickup device is disposed to face a subject, illumination is performed from N illumination directions, a first image captured from a first illumination direction is stored in a first memory, and a second image is stored in a first memory. The second image captured from the illumination direction is stored in the second memory, the darker pixel is selected by comparing the densities of the pixels at the same position in both images, and the first selected image is formed by the selected pixels. This is overwritten in the first memory, the third image captured from the third illumination direction is overwritten in the second memory, and the density of the pixel at the same position of the first selected image and the third image is compared to be dark. A second selected image is constituted by the pixels selected by selecting one of the pixels, and
Overwriting the memory, overwriting the fourth image captured from the fourth illumination direction into the second memory, comparing the density of the pixel at the same position of the second selected image and the fourth image, and determining the darker pixel A method for removing gloss in an image, comprising forming a third selected image with selected and selected pixels, overwriting this in a first memory, and thereafter obtaining an (N-1) th selected image in the same manner. 3. An imaging device arranged to face a subject, an illuminating device for illuminating the subject from a plurality of directions, respective memories for storing images taken for each direction of illumination, and An image selecting means for selecting the darkest pixel by comparing the densities of the pixels at the same position of the image and forming an image with the selected pixel. 4. An imaging device arranged to face an object, an illumination device for illuminating the object from N illumination directions, a first memory and a second memory for storing an image taken by the imaging device. , The first imaged from the first illumination direction
The image is stored in the first memory, the second image captured from the second illumination direction is stored in the second memory, and the darker pixel is selected by comparing the densities of the pixels at the same position in both images. A first selected image is constituted by the selected pixels, this is overwritten in a first memory, a third image captured from a third illumination direction is overwritten in a second memory, and the first selected image and the third image are overwritten. The second selected image is constituted by the pixels selected by comparing the densities of the pixels at the same position and selecting the darker pixel, this is overwritten in the first memory, and the second selected image is taken from the fourth illumination direction. The four images are overwritten in the second memory, the density of the pixels at the same position of the second selected image and the fourth image are compared, and the darker pixel is selected to form the third selected image. Image selecting means for overwriting this in the first memory and obtaining an (N-1) th selected image in the same manner;
An apparatus for removing gloss in an image, comprising: 5. The apparatus according to claim 3, wherein the number of the illuminating devices is one, and the illuminating device moves in each illuminating direction to illuminate.