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Image pickup apparatus and image processing method

a technology of image pickup and image processing, which is applied in the direction of color television details, color signal processing circuits, television systems, etc., can solve the problems of unnatural image picked up in the situation as a whole, unnatural combined image depending on the imaging scene, and narrow image dynamic range, so as to achieve the effect of broad dynamic range, and less discrepancy in white balan

Inactive Publication Date: 2007-04-05
FUJIFILM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an image pickup apparatus and image processing method that can combine image data from a high output image and a low output image while adjusting white balance and creating a broad dynamic range. The apparatus and method use a gain value to adjust white balance based on the scene and the amount of light received by the imaging device. This results in a natural combined image with minimal discrepancies in white balance and a broad dynamic range. The invention also provides an image pickup apparatus that includes two photoreceptors with different sensitivities to output signals corresponding to the amount of light received by the imaging device.

Problems solved by technology

The image picked up in the situation is unnatural as a whole.
Such problem comes from the fact that the dynamic range of an image is narrow.
Therefore, as a result of that white balances of the high sensitivity image and the low sensitivity image in the combined image are respectively different, the combined image comes to be unnatural depending on an imaging scene.
However, in the case of imaging under a low-contrast imaging condition such as a cloudiness or an interior, similar preferable effects are hardly achieved, or rather, the tone reproduction is wasted.
However, since simple addition gives an image in which the middle tone region that is strongly influential on image quality appears unnatural, weighted addition depending on signal levels is usually carried out.
However, even if a weighted addition depending on signal levels is performed, the white balance of the middle tone tends to differ from that of the highlights tone when each white balances of two images with high sensitivity and low sensitivity is not accurately adjusted.
As a result, a combination image comes to be unnatural.

Method used

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first embodiment

[0055]FIG. 1 is a block diagram of a digital still camera of first embodiment according to the invention. In the first embodiment, the digital still camera is explained for an example, while it is applicable to other types of an image pickup apparatus such as digital video cameras. An image combination operation in the embodiment is performed by software in a digital signal processing unit 26 to be described later, while the image combination operation can be also performed by a hardware circuit.

[0056] The digital still camera shown in FIG. 1 has an imaging lens 10, a solid-state image sensor 11, a lens diaphragm 12 that is positioned between the imaging lens 10 and a solid-state image sensor 11, an infrared-cut filter 13 and an optical low pass filter 14. A CPU 15, which controls the entire digital still camera, controls a light-emitting unit 16 and a light-receiving unit 17 both for photoflash, adjusts a lens-driving unit 18 to regulate the position of the imaging lens 10 to the ...

second embodiment

[0091] Configuration of a digital still camera according to second embodiment is same as that of a digital still camera according to the first embodiment shown in FIG. 1, except a digital signal processing unit. Therefore, a digital signal processing unit of the embodiment is denoted by “26a” in FIG. 6 and “26b” in FIG. 7.

[0092]FIG. 6 is a detailed block diagram of the digital signal processing unit 26a. This digital signal processing unit 26a may be constructed in the form of a hardware circuit or software. In the embodiment, the digital signal processing unit 26a will be described for the case where a low sensitivity image picked up with a high shutter speed (This image is also called “low output image”, since the output from each pixel is low.) and a high sensitivity image sequentially picked up with a low shutter speed (This image is also called “high output image”, since the output from each pixel is higher than the data of the low output image.) are combined.

[0093] The digit...

third embodiment

[0112] In third embodiment, descriptions will be given to the cases where the invention is applied to a digital still camera.

[0113] As shown in FIG. 8, a digital camera 100 as the embodiment has an optical lens 112, a diaphragm 114 which regulates the amount of light transmitting the optical lens 112, a shutter 116 which regulates the light-passing period, a CCD (Charge-Coupled Device) 118 as the image sensor which picks up a scene with high sensitivity and low sensitivity photoreceptors based on the impinging light, which representing the scene, transmitted the optical lens 112, the diaphragm 114 and the shutter 116 to output R, G and B three-color analog image signals.

[0114] The CCD 118 are, in the order, connected to an analog signal processing unit 120 which executes pre-determined analog signal processing on the high sensitivity and low sensitivity signals inputted by the CCD 118, and an analog / digital converter (hereafter, called “A / D converter”) 122 which converts the high ...

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PUM

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Abstract

An image combined high sensitivity image and low sensitivity image is provided with well-adjusted white balance and broad dynamic range. The image is obtained by multiplying the combined data by total gain that depends on scene. A white balance is adjusted with gain value calculated from of high output image data. Lv value representing luminance is calculated and compared with a threshold to decide whether or not the high sensitivity image and the low sensitivity image should be combined. First gamma correction unit performs gamma-correction for the image signal derived from the high sensitivity signal with first gamma character, second gamma correction unit performs gamma-correction for the image signal derived from the low sensitivity signal with second gamma character that is different from the first gamma character, and addition unit combines the image signal from the first gamma correction unit and the image signal from the second gamma correction unit.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus and an image processing method of obtaining an image with a broad dynamic range. [0003] 2. Description of the Related Art [Prior Art][0004] Dynamic range of image sensor such as CCD used in an image pickup device such as widely prevailing digital cameras are generally narrower than those of film. Hence, in the case of imaging imaging a high luminance subject, the amount of received light exceeds the dynamic range. Then, the output of the image sensor saturates to cause the missing of the information of the subject imaged. [0005] When, for example, an indoor scene is picked up by an imaging apparatus such as digital still cameras, it sometimes occurs that subjects present in the interior can be imaged well, but the blue sky observed through a window is imaged with saturation. The image picked up in the situation is unnatural as a whole. Such problem comes fr...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04N5/202H04N5/235H04N9/73
CPCH04N5/202H04N5/235H04N5/2355H04N9/69H04N9/735H04N23/70H04N23/741H04N23/88H04N23/83
Inventor TAMARU, MASAYASAKAMOTO, KOICHIICHIKAWA, KOJISUGIMOTO, MASAHIKOHYODO, MANABUTAKEMURA, KAZUHIKOKOBAYASHI, HIROKAZU
Owner FUJIFILM CORP