SIGNAL PROCESSING APPARATUS, IMAGE CAPTURING APPARATUS, CONTROL APPARATUS, SIGNAL PROCESSING METHOD, AND CONTROL METHOD

• US 20170257591A1
• Filed: 02/28/2017
• Published: 09/07/2017
• Est. Priority Date: 03/02/2016
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kobuse, Takenori
• Granted Patent: US 10,027,919 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 25/10 for transforming different wavelengths into image signals
• CPC Class Codes: H04N 25/443 by reading pixels from selected 2D regions of the array, e.g. for windowing or digital zooming
• CPC Class Codes: H04N 25/673 by using reference sources
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters

Abstract

A signal processing apparatus comprising: an analog-digital converter that converts an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other; and a determination unit that determines a signal level at which the plurality of reference signals are changed based on a distribution of the converted digital signal, wherein the analog-digital converter performs the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

Claims

1. A signal processing apparatus comprising:

an analog-digital converter that converts an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other; and

a determination unit that determines a signal level at which the plurality of reference signals are changed based on a distribution of the converted digital signal,

wherein the analog-digital converter performs the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

2. The signal processing apparatus according to claim 1, wherein the determination unit determines the signal level based on the distribution of the digital signal corresponding to an entire region of the pixel section of the image sensor.

3. The signal processing apparatus according to claim 1 further comprising a setting unit that sets a partial region of the pixel section,

wherein the determination unit determines the signal level based on the distribution of the digital signal corresponding to the partial region.

4. The signal processing apparatus according to claim 3 further comprising a detection unit that detects a main subject from the digital signal obtained from an entire region of the pixel section of the image sensor,

wherein the partial region is a region of the main subject.

5. The signal processing apparatus according to claim 3 further comprising a designation unit that designates the partial region.

6. The signal processing apparatus according to claim 1, further comprising:

a voltage supply unit that supplies analog signals of a plurality of predetermined different output levels to the analog-digital converter; and

a calculation unit that calculates a correction value for correcting the digital signal based on a plurality of digital signals obtained by converting the analog signals of the plurality of different output levels using the plurality of reference signals.

7. The signal processing apparatus according to claim 6, wherein the correction value includes a ratio between slopes of the plurality of reference signals and an offset amount.

8. The signal processing apparatus according to claim 1, further comprising a reference signal output unit that outputs the plurality of reference signals,

wherein the plurality of reference signals include a first reference signal and a second reference signal whose slope is steeper than the first reference signal, and the reference signal output unit changes the slope of the first reference signal based on the distribution of the digital signal.

9. The signal processing apparatus according to claim 1, wherein the image sensor outputs one frame'"'"'s worth of analog signals at a predetermined period, and

in case where recording of a still image is designated, the determination unit analyzes the distribution of the digital signal converted from the one frame'"'"'s worth of analog signals obtained immediately before the designation is performed, and determines the signal level.

10. The signal processing apparatus according to claim 1, wherein the image sensor outputs one frame'"'"'s worth of analog signals at a predetermined period, and

the determination unit analyzes the distribution of the digital signal at the predetermined period and, in a case where the signal level has changed based on a result of the analysis, notifies the analog-digital converter of the changed signal level.

11. An image capturing apparatus comprising:

an image sensor;

an analog-digital converter that converts an analog signal output from a pixel section of the image sensor to a digital signal using a plurality of reference signals having different slopes from each other; and

a determination unit that determines a signal level at which the plurality of reference signals are changed based on a distribution of the converted digital signal,

wherein the analog-digital converter performs the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

12. A control apparatus for controlling an analog-digital converter that converts an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other, the control apparatus comprising:

a determination unit that determines a signal level at which the plurality of reference signals are changed based on a distribution of a converted digital signal; and

a notification unit that notifies the analog-digital converter of the determined signal level,

wherein the analog-digital converter performs the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

13. A signal processing method comprising:

converting an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other; and

determining a signal level at which the plurality of reference signals are changed based on a distribution of the converted digital signal,

wherein upon converting the analog signal to the digital signal, the conversion is performed using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

14. A control method for controlling an analog-digital converter that converts an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other, the method comprising:

determining a signal level at which the plurality of reference signals are changed based on a distribution of a converted digital signal; and

notifying the analog-digital converter of the determined signal level,

wherein the analog-digital converter is controlled to perform the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.

15. A non-transitory computer-readable storage medium storing a program for causing a computer included in an image capturing apparatus to execute the steps of a control method for controlling an analog-digital converter that converts an analog signal output from a pixel section of an image sensor to a digital signal using a plurality of reference signals having different slopes from each other, the method comprises:

determining a signal level at which the plurality of reference signals are changed based on a distribution of a converted digital signal; and

notifying the analog-digital converter of the determined signal level,

wherein the analog-digital converter is controlled to perform the conversion using a reference signal having a steeper slope when the analog signal is equal to or greater than the signal level than when the analog signal is smaller than the signal level.