Short exposure time which is combined with a long exposure time in acccordance with a scene change

• US 8,063,946 B2
• Filed: 08/21/2008
• Issued: 11/22/2011
• Est. Priority Date: 09/28/2007
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Asoma, Akira
• Primary Examiner(s): HERNANDEZ, NELSON D
• Application Number:
  US12/195,493
• Publication Number:
  US 20090086085A1
• Time in Patent Office: 1,188 Days
• Field of Search: 348/221.1, 348/223.1, 348/227.1, 348/228.1, 348/229.1, 348/362, 348/361
• US Class Current: 348/222.1
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10152 Varying illumination
• CPC Class Codes: G06T 2207/30232 Surveillance
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors

Abstract

An image pickup apparatus includes an image pickup unit configured to output a long-exposure image signal with a relatively long exposure time and a short-exposure image signal with a relatively short exposure time; a signal processing unit configured to generate a combined image signal with a relatively wide dynamic range at least wider than that of the long-exposure image signal or that of the short-exposure image signal by combining the long-exposure image signal and the short-exposure image signal; a detection unit configured to generate a luminance integrated value of the combined image signal; and a control unit configured to perform exposure correction control using the luminance integrated value. The control unit initializes a correction value for use in the exposure correction control during a scene change.

Claims

1. An image pickup apparatus comprising:

a rotation control unit configured to rotate the image pickup apparatus and to output a signal indicating a rotation of the image pickup apparatus;

an image pickup unit configured to output a long-exposure image signal with a relatively long exposure time and a short-exposure image signal with a relatively short exposure time;

a signal processing unit configured to generate a combined image signal with a relatively wide dynamic range at least wider than that of the long-exposure image signal or that of the short-exposure image signal by combining the long-exposure image signal and the short-exposure image signal;

a detection unit configured to generate a luminance integrated value of the combined image signal; and

a control unit configured to perform exposure correction control using the luminance integrated value and to receive the signal indicating the rotation of the image pickup apparatus from the rotation control unit,

wherein the control unit initializes a correction value for use in the exposure correction control during the rotation of the image pickup apparatus in response to receipt of the signal indicating the rotation of the image pickup apparatus from the rotation control unit.

2. The image pickup apparatus according to claim 1, wherein the detection unit generates the luminance integrated value and a luminance histogram of the combined image signal, and

wherein the control unit performs the exposure correction control using the luminance integrated value and the luminance histogram.

3. The image pickup apparatus according to claim 2, wherein the control unit performs, during the scene change, an initialization process of minimizing a target luminance integrated value, which is a correction value used in performing underexposure correction and which is used in the exposure correction control.

4. The image pickup apparatus according to claim 2, wherein the control unit performs an initialization process of maximizing a target short exposure time, which is a correction value used in performing overexposure correction and which is used in the exposure correction control.

5. The image pickup apparatus according to claim 1, wherein the control unit initializes the correction value for use in the exposure correction control in the case where a change in the luminance integrated value obtained by the detection unit is greater than or equal to a predetermined value.

6. The image pickup apparatus according to claim 1, wherein the rotation control unit outputs a signal to the control unit that indicates an end of the rotation of the image pickup apparatus.

7. An image pickup method comprising:

outputting, by a rotation control unit configured to rotate the image pickup apparatus, a signal indicating a rotation of the image pickup apparatus;

outputting a long-exposure image signal with a relatively long exposure time and a short-exposure image signal with a relatively short exposure time;

generating a combined image signal with a relatively wide dynamic range at least wider than that of the long-exposure image signal or that of the short-exposure image signal by combining the long-exposure image signal and the short-exposure image signal;

generating a luminance integrated value of the combined image signal;

receiving, by a control unit, the signal indicating the rotation of the image pickup apparatus from the rotation control unit; and

performing, by the control unit, exposure correction control using the luminance integrated value,

wherein, in the exposure correction control performing step, a correction value for use in the exposure correction control is initialized during the rotation of the image pickup apparatus in response to receipt of the signal indicating the rotation of the image pickup apparatus from the rotation control unit.

8. The image pickup method according to claim 7, wherein, in the generating step, the luminance integrated value and a luminance histogram of the combined image signal are generated, and

wherein, in the exposure correction control performing step, the exposure correction control is performed using the luminance integrated value and the luminance histogram.

9. The image pickup method according to claim 8, wherein, in the exposure correction control performing step, an initialization process of minimizing a target luminance integrated value, which is a correction value used in performing underexposure correction and which is used in the exposure correction control, is performed during the scene change.

10. The image pickup method according to claim 9, wherein, in the exposure correction control performing step, an initialization process of maximizing a target short exposure time, which is a correction value used in performing overexposure correction and which is used in the exposure correction control, is performed during the scene change.

11. The image pickup method according to claim 8, wherein, in the exposure correction control performing step, the correction value for use in the exposure correction control is initialized when a change in the luminance integrated value obtained in the generating step is greater than or equal to a predetermined value.

12. A non-transitory computer readable storage medium encoded with instruction, which when executed by a computer causes the computer to execute an image pickup method, the image pickup method comprising:

outputting, by a rotation control unit configured to rotate the image pickup apparatus, a signal indicating a rotation of the image pickup apparatus;

outputting a long-exposure image signal with a relatively long exposure time and a short-exposure image signal with a relatively short exposure time;

generating a combined image signal with a relatively wide dynamic range at least wider than that of the long-exposure image signal or that of the short-exposure image signal by combining the long-exposure image signal and the short-exposure image signal;

generating a luminance integrated value of the combined image signal;

receiving, by a control unit, the signal indicating the rotation of the image pickup apparatus from the rotation control unit; and

performing, by the control unit, exposure correction control using the luminance integrated value,

wherein, in the exposure correction control performing step, a correction value for use in the exposure correction control is initialized during the rotation of the image pickup apparatus in response to receipt of the signal indicating the rotation of the image pickup apparatus from the rotation control unit.