Imaging device having light field image sensor
A method of imaging a target object with an imaging reader. The method includes the following: (1) detecting light from the target object through a lens arrangement with an image sensor to generate light-field data; (2) generating a stream of image data including image data representing an expected in-focus image of the target object, and (3) processing the expected in-focus image of the target object to decode a barcode on the target object. The image sensor includes an array of photosensitive elements and an array of microlenses that overlays the array of photosensitive elements located at a focus plane of the microlens.
1. A method of imaging a target object with an imaging reader, the method comprising:
detecting light from the target object through a lens arrangement with an image sensor to generate light-field data, wherein the image sensor comprises (1) an array of photosensitive elements and (2) an array of microlenses that overlays the array of photosensitive elements with a uniform spacing, wherein a microlens covers multiple photosensitive elements each receiving light through the microlens to function as a sub-pixel;
generating a stream of image data including image data representing an expected in-focus image of the target object, a stream of image data being generated from the light-field data;
selecting a set of predetermined focus planes each being titled with respect an optical axis of the lens arrangement; and
constructing a set of images of the target object from the light-field data, wherein each image in the set of images is constructed from the light-field data using one of the predetermined focus planes as a corresponding focus plane.
2. The method of claim 1 , further comprising:
generating a stream of image data including image data representing each image from the set of images.
3. The method of claim 1 , further comprising:
selecting one image from the set of images constructed from the light-field data as the expected in-focus image of the target object, wherein the one image that is selected has better sharpness than other images from the set of images.
4. A method of imaging a target object with an imaging reader, the method comprising:
detecting light from the target object through a lens arrangement with an image sensor to generate light-field data, wherein the image sensor comprises (1) an array of photosensitive elements and (2) an array of microlenses that overlays the array of photosensitive elements with a uniform spacing, wherein a microlens covers multiple photosensitive elements each receiving light through the microlens to function as a sub-pixel;
generating a stream of image data including image data representing an expected in-focus image of the target object, a stream of image data being generated from the light-field data;
constructing a reference image of the target object from the light-field data using a first focus plane as a corresponding focus plane;
comparing the reference image with an intensity distribution in the sub-pixels to selected one of a near focus plane, a far focus plane, and the first focus plane as a next focus plane, wherein the first focus plane is located between the near focus plane and the far focus plane; and
using the next focus plane to construct the expected in-focus image of the target object from the light-field data.
5. The method of claim 4 , wherein said comparing the reference image with an intensity distribution in the sub-pixels comprises:
comparing direction of black-to-white transition between micro-lenses and sub-pixels.
6. The method of claim 1 , further comprising:
determining an optimized synthesized aperture based on an intensity of light received from the target object; and
using the optimized synthesized aperture to construct the expected in-focus image of the target object from the light-field data.