Signal processing apparatus, image capturing apparatus, control apparatus, signal processing method, and control method

• US 10,027,919 B2
• Filed: 02/28/2017
• Issued: 07/17/2018
• 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
• Primary Examiner(s): Mai, Lam T
• Application Number:
  US15/445,273
• Publication Number:
  US 20170257591A1
• Time in Patent Office: 504 Days
• Field of Search: 341155-170
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• 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

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. An image sensing apparatus comprising:

a pixel section;

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

an analysis unit that analyzes a distribution of the digital signal; and

a controller that changes a signal level for selecting one of the plurality of reference signals to be used for conversion by the analog-digital converter based on a bias condition of the distribution of the digital signal.

2. The image sensing apparatus according to claim 1, wherein the controller changes the signal level based on the bias condition of the distribution of the digital signal corresponding to an entire region of the pixel section.

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

wherein the controller changes the signal level based on the bias condition of the distribution of the digital signal corresponding to the partial region.

4. The image sensing 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,

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

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

6. The image sensing 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 image sensing 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 image sensing 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 bias condition of the distribution of the digital signal.

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

in case where recording of a still image is designated, the analysis 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 image sensing apparatus according to claim 1, wherein the pixel unit outputs one frame'"'"'s worth of analog signals at a predetermined period, and

the analysis 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. The image sensing apparatus according to claim 1,

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.