IMAGE PICKUP APPARATUS AND IMAGE PICKUP ELEMENT

• US 20110063451A1
• Filed: 04/30/2009
• Published: 03/17/2011
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta OPTO Incorporated (Konica Minolta Inc.)
• Inventors: Takayama, Jun, Kamon, Koichi
• Granted Patent: US 8,723,958 B2
• Time in Patent Office: Days
• US Class Current: 348/164
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/20 for generating image signals from infrared radiation only
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/843 Demosaicing, e.g. interpolating colour pixel values
• CPC Class Codes: H04N 25/131 including elements passing infrared wavelengths
• CPC Class Codes: H04N 25/133 including elements passing panchromatic light, e.g. filters passing white light
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A luminance signal and a color information signal having high S/N ratios are generated by combining a visible luminance image component and an infrared image component at an appropriate ratio according to brightness of a subject such as brightness on a sunny day or brightness in darkness. An image pickup element 3 picks up a ye image component Dye, an R image component DR, an infrared image component DBlk and a luminance image component DW. An evaluation value calculator 41 calculates an evaluation value eDW and an evaluation value eDBlk by adding pixel values of the luminance image component DW and pixel values of the infrared image component DBlk in a local area, and calculates an evaluation value e (=eDW−eDBlk). A factor determiner 51 determines weighting factors k, kw from the evaluation value e. A signal generator 44 weights the luminance image component by the weighting factor k, weights the visible luminance image component by the weighting factor kw, combines the luminance image component and the visible luminance image component to calculate a luminance signal dY, and also calculates color signals dR, dG and dB.

Claims

1. An image pickup apparatus, comprising:

an image pickup element for picking up a visible color image component by pixels including color filters, an infrared image component by pixels including infrared filters and a luminance image component including a visible luminance image component and the infrared image component by pixels for receiving light at least in a visible wavelength region and an infrared wavelength region;

an evaluation value calculator for calculating an evaluation value used to evaluate brightness of a subject based on the luminance image component and the infrared image component;

a factor determiner for determining, using the evaluation value, a first weighting factor having a predetermined characteristic of increasing as the brightness of the subject increases and a second weighting factor having a predetermined characteristic of decreasing as the brightness of the subject increases; and

a signal generator for generating the visible luminance image component by subtracting the infrared image component from the luminance image component, generating a luminance signal by combining the visible luminance image component weighted using the first weighting factor determined by the factor determiner and the luminance image component or the infrared image component weighted using the second weighting factor determined by the factor determiner and generating a color information signal by combining the visible color image component, the infrared image component and the luminance image component.

2. An image pickup apparatus according to claim 1, wherein:

the image pickup element is such that unit pixel sections each including a first pixel, a second pixel, a third pixel and a fourth pixel and having the visible wavelength region and the infrared wavelength region as a sensitive wavelength band are arrayed in a matrix;

each first pixel includes a first color filter for transmitting light in the sensitive wavelength band excluding a blue region of the visible wavelength region;

each second pixel includes a second color filter for transmitting light in the sensitive wavelength band excluding blue and green regions of the visible wavelength region;

each third pixel includes a third color filter for transmitting light in the sensitive wavelength band excluding the visible wavelength region; and

each fourth pixel is a pixel for receiving light at least in the visible wavelength region and the infrared wavelength region.

3. An image pickup apparatus according to claim 1, further comprising:

an exposure correction value calculator for calculating an exposure correction value based on the first and second weighting factors determined by the factor determiner; and

an exposure corrector for applying an exposure correction to an image picked up by the image pickup element using the exposure correction value calculated by the exposure correction value calculator.

4. An image pickup apparatus according to claim 1, further comprising:

a white balance correction value calculator for calculating a white balance correction value based on the color information signal generated by the signal generator; and

a white balance corrector for applying a white balance correction to an image picked up by the image pickup element using the white balance correction value calculated by the white balance correction value calculator.

5. An image pickup apparatus according to claim 1, wherein the signal generator generates the luminance signal using the following equation:

dY=kw×

DW+k×

(DW−

DBlk)

where dY;

luminance signal, k;

first weighting factor, kw;

second weighting factor, DW;

luminance image component, DBlk;

infrared image component;

DW−

DBlk;

visible luminance image component.

6. An image pickup apparatus according to claim 1, wherein:

the color information signal includes color signals dR, dG and dB and color difference signals Cb, Cr; and

the image pickup apparatus further comprises a color space converter for determining 12 factors k1 to k12, which are predetermined to increase the weights of the visible luminance image component in the luminance signal dY generated by the signal generator as the visible luminance image component increases, based on the evaluation value or the first and second weighting factors and converting the luminance signal dY and the color signals dR, dG and dB into a color space represented by a luminance signal Y and the color difference signals Cb, Cr by the following equations using the determined factors k1 to k12;

Y=k1×

dY+k2×

dR+k3×

dG+k4×

dB

Cb=k5×

dY+k6×

dR+k7×

dG+k8×

dB

Cr=k9×

dY+k10×

dR+k11×

dG+k12×

dB.

7. An image pickup apparatus according to claim 1, wherein the factor determiner calculates the evaluation value in each pixel and determines the first and second weighting factors in each pixel.

8. An image pickup apparatus according to claim 1, further comprising a gain setter for setting a gain of the color information signal based on at least either one of brightness and darkness of a subject.

9. An image pickup element, characterized in that pixels including color filters, pixels including infrared filters and pixels for receiving light at least in a visible wavelength region and an infrared wavelength region are arrayed.