Method and apparatus for correcting a channel dependent color aberration in a digital image
First Claim
1. A method for correcting a channel dependent color aberration in a digital image, where the digital image comprises a plurality of color channels, said method comprising the steps of:
- capturing an image comprising a plurality of color channels, wherein one of the color channels is a blurred color channel due to a channel dependent color aberration affecting that channel;
using another color channel, other than the blurred color channel, as an indication of an aim sharpness; and
adjusting the sharpness of the blurred color channel, at least partially, toward the aim sharpness;
wherein the aim sharpness is a modulation transfer function (MTF) of the other color channel.
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Abstract
A method, and digital capture apparatus for use therewith, is described for correcting a channel dependent color aberration in a digital image, where the digital image is composed of a plurality of color channels. The method includes capturing an image comprising the color channels, where one of the color channels is a blurred color channel due to a channel dependent color aberration affecting that channel. Then, one of the other color channels, other than the blurred color channel, is used as an indication of an aim sharpness, and the sharpness of the blurred color channel is adjusted, at least partially, toward the aim sharpness.
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Citations
27 Claims
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1. A method for correcting a channel dependent color aberration in a digital image, where the digital image comprises a plurality of color channels, said method comprising the steps of:
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capturing an image comprising a plurality of color channels, wherein one of the color channels is a blurred color channel due to a channel dependent color aberration affecting that channel; using another color channel, other than the blurred color channel, as an indication of an aim sharpness; and adjusting the sharpness of the blurred color channel, at least partially, toward the aim sharpness; wherein the aim sharpness is a modulation transfer function (MTF) of the other color channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for correcting a channel dependent color aberration in a digital image, where the digital image comprises a plurality of color channels, said method comprising the steps of:
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capturing an image comprising a plurality of color channels, wherein one of the color channels is a blurred color channel due to a channel dependent color aberration affecting that channel; using another color channel, other than the blurred color channel, as an indication of an aim sharpness; and adjusting the sharpness of the blurred color channel, at least partially, toward the aim sharpness; wherein the aim sharpness is related to a modulation transfer function (MTF) of the other color channel used as an indication of the aim sharpness; and wherein the step of adjusting the sharpness of the blurred channel toward the aim sharpness comprises the steps of; determining the MTF of the blurred color channel and the MTF of the other color channel used as an indication of the aim sharpness; determining a ratio of the MTF of the other color channel to the MTF of the blurred color channel; using the ratio to generate a filter, wherein the ratio is the aim frequency response of the filter; and applying the filter to the blurred color channel to adjust the sharpness of the blurred color channel, at least partially, toward the aim sharpness. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method for correcting a longitudinal color aberration in a digital image, where the digital image comprises red, green and blue color channels imaged by an optical system having the aberration, and where the blue color channel is a blurred color channel due in particular to the longitudinal color aberration affecting that channel, said method comprising the steps of:
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(a) using another color channel, other than the blue color channel, as a measure of an aim sharpness; (b) measuring a modulation transfer function (MTF) of the optical system for at least the blue color channel and the other color channel used as a measure of aim sharpness; (c) computing a ratio of the MTF of the other color channel to the MTF of the blue color channel; (d) using the ratio to generate a filter; (e) capturing an image comprising the color channels, where the blue color channel is a blurred color channel due to the longitudinal color aberration; and (f) applying the filter to the blue color channel to equalize the sharpness of the blue color channel, at least partially, to the aim sharpness. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A digital camera for capturing a digital image, where the digital image comprises a plurality of color channels, said digital camera comprising:
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an optical system having a channel dependent color aberration; an image capture section for capturing an image comprising the color channels, where one of the color channels is a blurred color channel due to the channel dependent color aberration affecting that channel; a data store for storing a filter, wherein the filter is obtained by using another color channel, other than the blurred color channel, as an indication of an aim sharpness; and a processor for applying the filter to the blurred color channel to adjust the sharpness of the blurred color channel, at least partially, toward the aim sharpness; wherein the aim sharpness is a modulation transfer function (MTF) of the other color channel. - View Dependent Claims (27)
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Specification