Image pickup apparatus and a method for producing an image of quality matching with a scene to be captured

Abstract

An image pickup apparatus includes an image sensor in which main and auxiliary pixels are bidimensionally arranged for outputting a high and a low output signal, respectively. The user of the camera is allowed to select a desire image quality mode appearing on a monitor by operating a control panel. In a dynamic range priority mode, the high and low output signals are smoothly combined with each other to produce an image signal with a broadened dynamic range. In a resolution priority mode, the high and low output signals are not combined in order to guarantee resolution. In a sensitivity priority mode, the low output signal is added to the high output signal in order to raise the saturation point of the first output signal and therefore sensitivity. Further, in a color reproducibility priority mode, a white balance correcting method is changed depending upon the color temperature of a scene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become more apparent from consideration of the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic block diagram showing a preferred embodiment of the image pickup apparatus in accordance with the present invention;

FIG. 2 is a view of photodiodes arranged on the image sensing surface of an image sensor included in the apparatus of FIG. 1;

FIG. 3 is a graph plotting the output characteristics of main pixels and auxiliary pixels included in the arrangement of FIG. 2;

FIG. 4 is a rear plan view of a specific configuration of the back of the apparatus shown in FIG. 1;

FIG. 5 is a functional block diagram schematically showing a specific configuration of a signal processor included in the apparatus of FIG. 1;

FIG. 6 demonstrates RGB interpolation processing executed by the signal processor of FIG. 5;

FIGS. 7A, 7B and 7C show other specific patterns in which pixels may be arranged in the image sensor of FIG. 1;

FIG. 8 is a functional block diagram schematically showing another specific configuration of the signal processor included in the apparatus of FIG. 1;

FIG. 9 is a graph useful for understanding combination processing executed by the signal processor of FIG. 8;

FIG. 10 is a functional block diagram schematically showing still another specific configuration of the signal processor included in the apparatus of FIG. 1;

FIGS. 11A and 11B are graphs useful for understanding how a dynamic range is broadened by combination processing included in the signal processor of FIG. 5;

FIG. 12 is a functional block diagram schematically showing a further specific configuration of the signal processor included in the apparatus of FIG. 1;

FIGS. 13A through 13F are graphs useful for understanding the problem of conventional white balance correction;

FIGS. 14A through 14F plot output signals achievable with white balance correction executed by the signal processor of FIG. 12;

FIGS. 15A and 15B are graphs useful for understanding the comparison of spectral sensitivity ratios particular to conventional technologies with spectral sensitivity ratios achievable with the signal processor of FIG. 12;

FIG. 16 is a flowchart demonstrating a specific image processing sequence unique to the embodiment of FIG. 12; and

FIG. 17 is a flowchart showing an automatic image pickup environment analysis procedure executed by a system controller included in the apparatus of FIG. 1.

Claims

1. An image pickup apparatus comprising: a solid-state image pickup device in which pixels, constituted by first photosensitive portions and second photosensitive portions lower in sensitivity than said first photosensitive portions, are bidimensionally arranged to form a single frame, said solid-state image pickup device being capable of producing, by combining a first output signal and a second output signal produced from said first photosensitive portions and said second photosensitive portions, respectively, according to a predetermined rule, an image signal having a broader dynamic range than the first output signal; anda signal processor for generating, in a mode giving priority to resolution, an image signal in which the first output signal and the second output signal are used independently of each other without being combined over the single frame.

2. The apparatus in accordance with claim 1, wherein said first photosensitive portions and said second photosensitive portions are arranged in either one of a honeycomb pattern and a Bayer pattern in a single layer or a plurality of layers.

3. The apparatus in accordance with claim 1, wherein said apparatus comprises a digital camera.

4. The apparatus in accordance with claim 1, wherein said apparatus comprises a cellular phone.

5. An image pickup apparatus comprising: a solid-state image pickup device in which pixels, constituted by first photosensitive portions and second photosensitive portions lower in sensitivity than said first photosensitive portions, are bidimensionally arranged to form a single frame, said solid-state image pickup device being capable of producing, by combining a first and a second output signal produced from said first photosensitive portions and said second photosensitive portions, respectively, according to a predetermined rule, an image signal having a broader dynamic range than the first output signal; anda signal processor for generating, in a mode giving priority to sensitivity, an image signal by adding the first output signal and the second output signal over the single frame.

6. The apparatus in accordance with claim 5, wherein said first photosensitive portions and said second photosensitive portions are arranged in either one of a honeycomb pattern and a Bayer pattern in a single layer or a plurality of layers.

7. The apparatus in accordance with claim 5, wherein said apparatus comprises a digital camera.

8. The apparatus in accordance with claim 5, wherein said apparatus comprises a cellular phone.

9. An image pickup apparatus comprising: a solid-state image pickup device in which pixels, constituted by first photosensitive portions and second photosensitive portions lower in sensitivity than said first photosensitive portions, are bidimensionally arranged to form a single frame, said solid-state image pickup device being capable of producing, by combining a first and a second output signal produced from said first photosensitive portions and said second photosensitive portions, respectively, according to a predetermined rule, an image signal having a broader dynamic range than the first output signal; anda signal processor for combining, in a mode giving priority to color reproducibility and for an amount of exposure causing said first photosensitive portions corresponding to predetermined one of colors, red (R), green (G) and blue (B), to saturate, a saturation output signal of said first photosensitive portions and an output signal of said second photosensitive portions corresponding to the predetermined color in a predetermined ratio and then establish white balance between a resulting composite output signal and the output signal of said first photosensitive portions corresponding to another color.

10. The apparatus in accordance with claim 9, wherein a spectral sensitivity ratio between R, G and B is 1:1:1.

11. The apparatus in accordance with claim 9, wherein said first photosensitive portions and said second photosensitive portions are arranged in either one of a honeycomb pattern and a Bayer pattern in a single layer or a plurality of layers.

12. The apparatus in accordance with claim 9, wherein said apparatus comprises a digital camera.

13. The apparatus in accordance with claim 9, wherein said apparatus comprises a cellular phone.

14. A method of processing an image wherein a solid-state image pickup device is used in which pixels, constituted by first photosensitive portions and second photosensitive portions lower in sensitivity than the first photosensitive portions, are bidimensionally arranged to form a single frame, the solid-state image pickup device being capable of producing, by combining a first and a second output signal produced from the first photosensitive portions and the second photosensitive portions, respectively, according to a predetermined rule, an image signal having a broader dynamic range than the first output signal, said method comprising the steps of: selecting any one of a resolution priority mode giving priority to resolution, a sensitivity priority mode giving priority to sensitivity and a color reproducibility priority mode giving priority to color reproducibility;generating, when the resolution priority mode is selected, an image signal using the first output signal and the second output signal without combining the first output signal and the second output signal over the single frame;generating, when the sensitivity priority mode is selected, an image signal by adding the first output signal and the second output signal produced from the first photosensitive portions and the second photosensitive portions, respectively, over the single frame; andgenerating, when the color reproducibility priority mode is selected, an image signal by combining, for an amount of exposure causing the first photosensitive portions corresponding to predetermined one of colors, red (R), green (G) and blue (B), to saturate, a saturation output signal of the first photosensitive portions and an output signal of the second photosensitive portions corresponding to the predetermined color in a predetermined ratio and then establishing white balance between a resulting composite output signal and the output signal of the first photosensitive portions corresponding to another color;whereby an image signal matching with a user's selection is provided.

15. A method of processing an image where in solid-state image pickup device is used in which pixels, constituted by first photosensitive portions and second photosensitive portions lower in sensitivity than the first photosensitive portions, are bidimensionally arranged to form a single frame, the solid-state image pickup device being capable of producing, by combining a first and a second output signal produced from the first photosensitive portions and the second photosensitive portions, respectively, according to a predetermined rule, an image signal having a broader dynamic range than the first output signal, said method comprising the steps of: selecting any one of a resolution priority mode giving priority to resolution, a sensitivity priority mode giving priority to sensitivity and a color reproducibility priority mode giving priority to color reproducibility in accordance with a pickup environment;generating, when the resolution priority mode is selected, an image signal using the first output signal and the second output signal without combining the first output signal and the second output signal over the single frame;generating, when the sensitivity priority mode is selected, an image signal by adding the first output signal and the second output signal produced from the first photosensitive portions and the second photosensitive portions, respectively, over the single frame; andgenerating, when the color reproducibility priority mode is selected, an image signal by combining, for an amount of exposure causing the first photosensitive portions corresponding to predetermined one of colors, red (R), green (G) and blue (B), to saturate, a saturation output signal of the first photosensitive portions and an output signal of the second photosensitive portions corresponding to the predetermined color in a predetermined ratio and then establishing white balance between a resulting composite output signal and the output signal of the first photosensitive portions corresponding to another color;whereby an image signal matching with a pickup environment is provided.