JPH11331686A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image input device that synthesizes images by photographing the image whose exposure is in matching with an object of high luminance with a constant iris with that of an image whose exposure is in matching with an object of a low luminance. So as to avoid a difference from depth of focus between the images to be combined and deterioration of the resolution of an optical system in the image input device that uses a photoelectric conversion element (such as CCD) so as to combine an image whose exposure is properly in matching with an object of high luminance and an image whose exposure is in matching with an object of a low luminance. SOLUTION: In the case of photographing an image whose exposure is in matching with an object of high luminance, an ND filter 101 that extincts light is inserted to a position of an iris 102 and the image is photographed with a constant iris 102 with that of an image whose exposure is in matching with an object of a low luminance. Then the images are combined without deteriorating resolution of an optical system and a difference from depth of focus between the images to be combined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image input apparatus which realizes dynamic range image input with a wide illuminance using a photoelectric conversion element.

[0002]

2. Description of the Related Art An image input device using a photoelectric conversion element (for example, a CCD) synthesizes an image properly exposed to a high-brightness portion and an image properly exposed to a low-brightness portion, so that a high-brightness subject and a low-brightness portion are combined. Conventionally, in an image input device that captures both objects with high brightness, an image that has been exposed brightly by opening an iris (or aperture) and an image that has been exposed darker by narrowing the iris have conventionally been synthesized. There is a problem that the depth of focus is different between two images, and that the resolution of an image with a narrowed iris is reduced and the resolution of a synthesized image is reduced.

FIG. 3 is a block diagram of a conventional image input device, showing an example of a method for expanding a dynamic range. The light from the subject is the optical lens 300 and the iris 3
01, the image is converged on the photoelectric conversion element 303 through the shutter 302, basic processing is performed in the preprocessing unit 304, and stored as one digital image in the image processing unit 305. At this time, the dynamic range of the photoelectric conversion element 303 with respect to the light input is narrow, so that when the exposure is adjusted to a dark subject, the bright portion is crushed and becomes white, but the iris 301 is adjusted by adjusting the exposure to the dark subject.
306 (an image in which a bright part is crushed but a dark part is appropriately captured) and an image 307 which is obtained by adjusting the exposure to a bright subject and narrowing the iris.
(A dark part is darkened in black, but a bright part is an image in which the gradation is reproduced). By obtaining a composite image 308 obtained by synthesizing an appropriately imaged part, a wide dynamic range is reproduced as the composite image 308. Images can be obtained. 309 is a shutter control unit, and 310 is an iris control unit.

[0004]

However, in the above-mentioned conventional method, since the iris is different, the depth of focus is different between the two images to be synthesized, and the image in which the iris is narrowed is an optical system. There was a problem that the resolution was reduced.

Therefore, according to the present invention, an image in which exposure is performed on a low-luminance object and an image obtained by imaging with a constant iris are combined, and the images are combined without a difference in the depth of focus and a decrease in the resolution of the optical system. It is an object of the present invention to provide an image input device capable of performing such operations.

[0006]

SUMMARY OF THE INVENTION The present invention provides an optical lens for converging light from a subject, an iris, an ND filter for dimming light at the position of the iris, a shutter, a photoelectric conversion element, and An iris control unit, an image processing unit for obtaining a composite image by combining images of the
A D filter control unit, and a difference in the depth of focus between images synthesized by imaging with a constant iris between an image in which exposure is performed on a low-brightness subject and an image in which exposure is performed on a high-brightness subject, And an image input device for synthesizing an image without lowering the resolution of the optical system.

[0007] With this configuration, it is possible to synthesize images without a difference in focal depth between images to be synthesized by capturing an image obtained by adjusting exposure to a low-brightness subject and an iris to be constant, and reducing the resolution of an optical system. Can be.

[0008]

According to the first aspect of the present invention, there is provided an optical lens for converging light from a subject, an iris, an ND filter for reducing light at a position of the iris, a shutter, a photoelectric conversion element, An image processing unit that combines the images of the high-brightness part and the low-brightness part to obtain a combined image, an iris control unit, and an ND filter control unit. The image input apparatus is characterized in that images are synthesized without differences in the depth of focus between images to be synthesized by capturing images and reducing the resolution of an optical system.

With this configuration, there is no difference in the depth of focus when the image obtained by exposing a high-luminance subject and the image obtained by exposing a low-luminance subject is combined to expand the dynamic range of luminance. The image can be synthesized without deterioration.

According to a second aspect of the present invention, when the condition for properly exposing the high-brightness portion by the photometric processing unit is a brightness that can be followed by the speed of the shutter, the ND filter control unit causes the ND filter to be controlled. A fixing control unit without an ND filter for fixing toward a lower transmittance was provided.

With this configuration, it is possible to automatically switch between the presence and absence of control by the ND filter.

(Embodiment 1) FIG. 1 is a configuration diagram of an image input apparatus according to Embodiment 1 of the present invention. Light from the subject is converged by the optical lens 100, and the ND filter 1
01, iris 102, shutter 103, CC
An image is formed on a D (photoelectric conversion element) 104. The ND filter 101 can switch between high transmittance (or a state without the ND filter) and low transmittance, and diminishes the light at the position of the iris 102. CCD (photoelectric conversion element) 104
The light is converted into an electric signal by the pre-processing unit 105, converted into an image in a standard format (for example, a YCrCb component signal or an image divided into RGB planes) by the pre-processing unit 105, and stored in the memory of the image processing unit 106. It is stored as a single image.

The image processing unit 106 stores a properly exposed image 107 in a high-brightness part and a properly exposed image 108 in a low-brightness part as two images. In the image 108, the high-luminance portion is saturated with white or a portion having a low gradation level at a level close to the saturation is brought to the high-luminance portion from the properly exposed image 107. At this time, the iris 102 is fixed as a photographing condition of two images. When an image 107 with proper exposure is captured in a high-luminance part, the ND filter 101 is set to a lower transmittance,
ND when capturing an image 108 with proper exposure in the low-brightness area
The filter 101 is set to a higher transmittance.

The setting is automatically switched by the ND filter control unit 112 by the photometric processing performed by the preprocessing unit 105. Also, iris 102 and shutter 1
03 is controlled by the pre-processing unit 105 to the shutter control unit 110 and the iris control unit 111. As described above, with the iris fixed at a certain value, the image 107 properly exposed to the high-brightness area and the image 108 properly exposed to the low-brightness area
Is captured to obtain a composite image 109, so that it is possible to obtain a composite image having no difference in the depth of focus and the resolution of the optical system.

(Embodiment 2) FIG. 2 is a configuration diagram of an image input apparatus according to Embodiment 2 of the present invention. Light from the subject is converged by the optical lens 200, and the ND filter 2
01, iris 202, shutter 203, CC
An image is formed on a D (photoelectric conversion element) 204. The ND filter 201 has a configuration capable of switching between high transmittance (or a state without the ND filter) and low transmittance. The light is converted into an electric signal by a CCD (photoelectric conversion element) 204 and the pre-processing unit 2
05 standard format images (eg, YCrC
b) or converted to an RGB plane) and stored in the memory of the image processing unit 206.
It is stored as a single image.

The image processing unit 206 stores an image 207 of proper exposure in a high-brightness part and an image 208 of proper exposure in a low-brightness part as two images. In the image 208, a high luminance portion is saturated with white, or a portion having a low gradation at a level close to the saturation is brought from the image 207 of the appropriate exposure to the high luminance portion. At this time, the iris 202 is fixed as a photographing condition of two images. The ND filter 201 is set to a lower transmittance when the image 207 of the proper exposure is captured in the high-brightness part, and the ND filter 201 is set to the higher transmittance when the image 208 of the proper exposure is captured in the low-brightness part. Set toward.

This setting is made when the photometry processing unit 213 of the preprocessing unit 205 determines that the condition for properly exposing the high-brightness portion is a brightness that the speed of the shutter 203 can follow.
The ND filter-free fixing control unit 214 operates to fix the ND filter 201 toward the lower transmittance and perform imaging. or,
If the photometry processing unit 213 of the preprocessing unit 205 determines that the condition for properly exposing the high-brightness area is a brightness that the speed of the shutter 203 cannot follow, the ND filter-free fixed control unit 214 does not operate and the ND filter control unit 212 Operates to capture the properly exposed image 207 in the high-brightness area, sets the ND filter 201 to the lower transmittance, and to capture the appropriately exposed image 208 in the low-brightness area, sets the ND filter 201 to the lower transmittance. It operates to set higher transmittance.

As described above, with the iris fixed at a certain value, an image 207 with proper exposure in the high-brightness area and an image 208 with proper exposure in the low-brightness area are taken to obtain a composite image 209. , It is possible to obtain a composite image having no difference in resolution.

[0019]

As described above, according to the present invention, when an image in which exposure is performed on a high-luminance subject and an image in which exposure is performed on a low-luminance subject are combined to expand the dynamic range of luminance, the depth of focus is increased. Images can be synthesized without any difference in image resolution.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image input device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an image input device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional image input device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 optical lens 101 ND filter 102 iris 103 shutter 104 photoelectric conversion element (CCD) 105 pre-processing unit 106 image processing unit 107 image properly exposed to high-luminance part 108 image properly exposed to low-luminance part 109 composite image 110 shutter control Unit 111 Iris control unit 112 ND filter control unit 200 Optical lens 201 ND filter 202 Iris 203 Shutter 204 Photoelectric conversion element (CCD) 205 Pre-processing unit 206 Image processing unit 207 High-luminance part properly exposed image 208 Low-luminance part Appropriate exposure image 209 Composite image 212 ND filter control unit 213 Photometry processing unit 214 Fixed control unit without ND filter

Claims (2)

[Claims] An optical lens for converging light from a subject;
An iris, an ND filter that dims light at the position of the iris, a shutter, a photoelectric conversion element, an image processing unit that combines the images of the high-brightness part and the low-brightness part to obtain a combined image, and an iris control unit. , An ND filter control unit,
The difference in the depth of focus between the images synthesized by imaging the iris at a constant level between the image that is exposed to the low-brightness subject and the image that is exposed to the high-brightness subject, and without lowering the resolution of the optical system An image input device for combining images. 2. A method according to claim 1, wherein the ND filter control unit determines that the condition for properly exposing the high-brightness portion by the photometric processing unit is a brightness that the shutter speed can follow.
2. The image input device according to claim 1, further comprising an ND filter-free fixing control unit for fixing the filter to a lower transmittance.