Phase detection autofocus using masked and unmasked photodiodes

Patent metadata

Field	Value
Publication number	US-9804357-B2
Application number	US-201514865629-A
Country	US
Kind code	B2
Filing date	Sep 25, 2015
Priority date	Sep 25, 2015
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

Certain aspects relate to systems and techniques for using imaging pixels (that is, non-phase detection pixels) in addition to phase detection pixels for calculating autofocus information. Imaging pixel values can be used to interpolate a value at a phase detection pixel location. The interpolated value and a value received from the phase difference detection pixel can be used to obtain a virtual phase detection pixel value. The interpolated value, value received from the phase difference detection pixel, and the virtual phase detection pixel value can be used to obtain a phase difference detection signal indicating a shift direction (defocus direction) and a shift amount (defocus amount) of image focus.

First claim

What is claimed is:

1. An imaging apparatus comprising:
a plurality of diodes each configured to capture one of
image information representing a target scene, the image information received from a first subset of the plurality of diodes, or
phase detection information, the phase detection information received from a second subset of the plurality of diodes; and

a processor configured with instructions to
for each diode of the second subset of the plurality of diodes
access the phase detection information received from the diode,
determine, using image information received from a predetermined plurality of diodes around a location of the diode, a center value corresponding to the location of the diode, and
determine, from the center value and the accessed phase detection information, a virtual phase detection value corresponding to the location, construct at least two of
a phase detection image from the phase detection information from at least some of the second subset of the plurality of diodes,
a center image from the center value for each of the second subset of the plurality of diodes, and
a virtual phase detection image from the virtual phase detection value for the at least some of the second subset of the plurality of diodes,

calculate a phase difference between two of the constructed images, and
determine an autofocus adjustment based on the phase difference.

2. The imaging apparatus of claim 1 , wherein the processor is configured to determine the virtual phase detection value by subtracting a phase detection value received from the diode at the location from the center value.

3. The imaging apparatus of claim 1 , wherein the processor is configured to determine the center value by interpolating the center value using the image information received from received from the predetermined plurality of diodes around the location.

4. The imaging apparatus of claim 1 , wherein the processor is configured to calculate the phase difference between the center image and the virtual phase detection image.

5. The imaging apparatus of claim 1 , wherein the second subset of the plurality of diodes comprise a plurality of pairs of opposing phase detection diodes.

6. The imaging apparatus of claim 5 , wherein the processor is configured to, for each diode of the second subset of the plurality of diodes:
identify an opposing phase detection diode; and
identify an opposing phase detection image and opposing virtual phase image corresponding to the opposing phase detection diode.

7. The imaging apparatus of claim 6 , wherein the processor is configured to identify phase differences between all possible pairs of the center image, phase detection image, opposing phase detection image, virtual phase image, and opposing virtual phase image.

8. The imaging apparatus of claim 7 , wherein the processor is configured to calculate the autofocus adjustment based on the phase differences.

9. The imaging apparatus of claim 1 , further comprising a masking element positioned above each of the second subset of the plurality of diodes to block a portion of light propagating from the target scene so each of the second subset of the plurality of diodes only collects the light propagating from the target scene in a specific direction.

10. The imaging apparatus of claim 1 , further comprising a microlens positioned above at least two adjacent diodes of the second subset of the plurality of diodes, the microlens formed to pass a first portion of light propagating from the target scene to a first of the at least two adjacent diodes and a second portion of light propagating from the target scene to a second of the at least two adjacent diodes, the first portion propagating in a first direction and the second portion propagating in a second direction.

11. The imaging apparatus of claim 1 , wherein the plurality of diodes comprise a semiconductor substrate having a two-dimensional matrix of the plurality of diodes.

12. The imaging apparatus of claim 1 , wherein optical elements associated with a first half of the second subset of the plurality of diodes are configured such that each diode of the first half of the second subset of the plurality of diodes only collects light propagating from the target scene in a first direction to generate a first half of the phase detection information.

13. The imaging apparatus of claim 10 , wherein optical elements associated with a second half of the second subset of the plurality of diodes are configured such that each diode of the second half of the second subset of the plurality of diodes only collects light propagating from the target scene in a second direction to generate a second half of the phase detection information.

14. The imaging apparatus of claim 1 , wherein each of the second subset of the plurality of diodes receives light propagating from the target scene through a light-blocking mask, and wherein determining the center value comprises interpolating the center value based on values received from a 3×3 neighborhood of the first subset of the plurality of diodes around the location.

15. The imaging apparatus of claim 1 , wherein each of the second subset of the plurality of diodes receives light incident from the target scene through a multi-diode microlens, and wherein determining the center value comprises interpolating the center value based on values received from a 3×4 neighborhood of the first subset of the plurality of diodes around the location.

16. The imaging apparatus of claim 15 , wherein determining the virtual phase detection value for each diode positioned under the multi-diode microlens comprises using the center value.

17. A processor configured with instructions for performing a process for phase detection autofocus, the process comprising:
accessing image information representing a target scene from a plurality of imaging diodes;
for each phase detection diode of a plurality of phase detection diodes positioned at a corresponding plurality of locations within a two-dimensional arrangement of the plurality of imaging diodes
accessing phase detection information received from the phase detection diode,
determining, using image information received from a predetermined plurality of diodes around a location of the phase detection diode, a center value corresponding to the location of the phase detection diode, and
determining, from the center value and the accessed phase detection information, a virtual phase detection value corresponding to the location;

constructing at least two of
a phase detection image from the phase detection information for each of the plurality of phase detection diodes,
a center image from the center value for each of the plurality of phase detection diodes, and
a virtual phase detection image from the virtual phase detection value for each of the plurality of phase detection diodes;

calculating a phase difference between two of the constructed images; and
determining an autofocus adjustment based on the phase difference.

18. The processor of claim 17 , wherein the plurality of phase detection didoes are positioned at a corresponding plurality of locations within a two-dimensional arrangement of the plurality of imaging diodes, and wherein the processor is configured with instructions for interpolating the center value using values received from the predetermined imaging diodes around the location.

19. The processor of claim 18 , wherein each phase detection diode receives light propagating from the target scene through a clear color filter or thro

Assignees

• Qualcomm Inc

Inventors

• Galor Gluskin Micha
• Velarde Ruben Manuel
• Lee Jisoo

Classifications

• H04N23/843

  Demosaicing, e.g. interpolating colour pixel values · CPC title

• H04N23/672 Primary

  based on the phase difference signals · CPC title

• H04N25/134

  based on three different wavelength filter elements · CPC title

• H04N25/704

  Pixels specially adapted for focusing, e.g. phase difference pixel sets · CPC title

• G02B7/34

  using different areas in a pupil plane · CPC title