System for enhancing depth of field with digital image processing

An electronic device comprising:

• an image sensor that captures an image that includes multiple image areas;
• storage and processing circuitry that manipulates depth of field in the image by processing the image, wherein the storage and processing circuitry is configured to manipulate the depth of field of the image by:
• calculating an inferred defocus metric for each image area;
• and
• sharpening at least some of the image areas by an amount that depends on the calculated inferred defocus metric for each image area, wherein the image areas comprise a first image area that has a first signal-to-noise ratio, a second image area that has a second signal-to-noise ratio, and a third area that has a third signal-to-noise ratio, wherein the first signal-to-noise ratio is less than the second signal-to-noise ratio, wherein the second signal-to-noise ratio is less than the third signal-to-noise ratio, and wherein the storage and processing circuitry is configured to sharpen the second image area more than the first and third image areas.

A method for using storage and processing circuitry to process an image captured by an image sensor in an electronic device, wherein the image has multiple image areas, the method comprising:

• calculating a respective inferred defocus metric value for each image area using the storage and processing circuitry;
• with the storage and processing circuitry, enhancing depth of field of the image by sharpening each image area by an amount that depends on the inferred defocus metric for that image area;
• and
• determining how much sharpening to apply to each image area using a sharpness strength characteristic that relates sharpening strength to signal-to-noise ratio values for the image areas and that has both positive and negative slopes.