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US 6,833,862 B1Granted
Image sensor based vignetting correction
AssigneeLogitech, Inc.
InventorWei Li
Life of this patent
Estimating the term…
Abstract
A method and apparatus for constructing an inexpensive camera with vignetting correction in the camera electronic hardware. The hardware is programmable through the use of a register storing a constant value corresponding to the amount of vignetting of a particular lens used in the camera. The register value is provided to a correction circuit which implements an algorithm that corrects for the amount of vignetting of pixels depending upon the pixel position.
Claims15
A method for manufacturing a camera which connects to a computer, comprising:
- determining a vignetting effect of a first lens;
- installing said first lens in a first camera housing;
- determining a vignetting effect of a second lens;
- installing said second lens in a second camera housing;
- installing in each housing a photosensor array mounted behind said lens;
- coupling an analog processing circuit to each said photosensor array;
- coupling an analog to digital converter to each said analog processing circuit;
- coupling a digital processing circuit to an output of each said analog to digital converter, said digital processing circuit including
- a register for storing a single vignetting constant corresponding to a vignetting rating of said lens, and
- a correction circuit, coupled to said register, for adjusting a value of selected pixels according to a formula using said single vignetting constant and a set of pixel coordinates to scale the single vignetting constant based on a distance of the selected pixels from an approximately central pixel, to correct for vignetting of said lens;
- coupling a bus interface circuit to an output of each said digital processing circuit for connecting to a bus for transfer of data to said computer;
- storing a first vignetting constant in said register in said first camera housing, said first vignetting constant corresponding to said vignetting effect of said first lens;
- storing a second vignetting constant in said register in said second camera housing, said second vignetting constant corresponding to said vignetting effect of said second lens.
10 more elements
A camera for connecting to a computer, comprising:
- a lens;
- a photosensor array mounted behind said lens;
- an analog processing circuit coupled to said photosensor array;
- an analog to digital converter coupled to said analog processing circuit;
- a digital processing circuit coupled to an output of said analog to digital converter, said digital processing circuit including
- a register for storing a single vignetting constant corresponding to a vignetting rating of said lens, and
- a correction circuit, coupled to said register, for adjusting a value of selected pixels according to a formula using said single vignetting constant and a set of pixel coordinates to scale the single vignetting constant based on a distance of the selected pixels from an approximately central pixel, to correct for vignetting of said lens;
- and
- a bus interface circuit coupled to an output of said digital processing circuit for connecting to a bus for transfer of data to said computer.
6 more elements
Dependencies are inferred from the claim text.