Mechanism for deriving noise-reduced estimates of color signal parameters from multiple color/luminance image sensor outputs
First Claim
1. For use with a multiple band image sensor system having a plurality of first image sensors, each of which produces a respective first sensor output signal that contains an information component representative of a respective characteristic of an image and a noise component associated with the operation of a sensor through which its output signal is produced, and a further image sensor that produces a further sensor output signal containing an information component representative of a further characteristic of said image, and which is expressible as a function of the information components of said first sensor output signals, and a noise component associated with the operation of said further image sensor, a method of processing said first and further sensor output signals to reduce the noise components in said first sensor output signals and thereby derive noise-reduced estimates of each of the information components within said first sensor output signals comprising the steps of:
- (a) generating a first signal, representative of said further image sensor signal, as a function of said first sensor output signals;
(b) generating a second signal representative of a prescribed relationship between said first signal and said further sensor output signal; and
(c) combining the first sensor output signals produced by said first image sensors with said second signal generated in step (b), to obtain said noise-reduced estimates of the information components of each of said first sensor output signals.
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Abstract
Color and luminance measurement signals produced by the multiple sensors of a multiband (e.g. RGB color) image signal processing system are processed to reduce noise. For images such as those obtained from a multi-dye film, the luminance component of the output signal from the luminance sensor may be expressed as a function of the color components of the color sensor output signals. A first signal, representative of the constructed low frequency luminance signal, is produced as a linear function of the color sensor output signals, employing signal weighting coefficients derivable from intrinsic characteristics of the scanned image, such as the respective dye densities of a three layer color film. The luminance measurement signal derived from the luminance sensor is subtracted from this first signal, to produce a second signal, which is multiplied by a set of respective scaling factors, which are then subtracted from each color sensor output, so as to derive a set of noise-reduced estimates of the color components of each of the color sensor output signals. Each scaling factor is defined in accordance with the noise variances associated with the operation of the color image sensors and the luminance image sensor, and is proportional to a product of a corresponding one of the coefficients and the ratio of the noise variance associated with the operation of a respective color image sensor to a summation of the noise variances associated with the operation of each of the color sensors and the luminance sensor.
28 Citations
27 Claims
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1. For use with a multiple band image sensor system having a plurality of first image sensors, each of which produces a respective first sensor output signal that contains an information component representative of a respective characteristic of an image and a noise component associated with the operation of a sensor through which its output signal is produced, and a further image sensor that produces a further sensor output signal containing an information component representative of a further characteristic of said image, and which is expressible as a function of the information components of said first sensor output signals, and a noise component associated with the operation of said further image sensor, a method of processing said first and further sensor output signals to reduce the noise components in said first sensor output signals and thereby derive noise-reduced estimates of each of the information components within said first sensor output signals comprising the steps of:
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(a) generating a first signal, representative of said further image sensor signal, as a function of said first sensor output signals; (b) generating a second signal representative of a prescribed relationship between said first signal and said further sensor output signal; and (c) combining the first sensor output signals produced by said first image sensors with said second signal generated in step (b), to obtain said noise-reduced estimates of the information components of each of said first sensor output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. For use with a multiple band image sensor system having a plurality of first image sensors, each of which produces a respective first sensor output signal that contains an information component representative of a respective characteristic of an image and a noise component associated with the operation of the sensor through which its output signal is produced, and a further image sensor that produces a further sensor output signal containing an information component that is representative of a further characteristic of said image, and is expressible as a function of the information components of said first sensor output signals, and a noise component associated with the operation of said further image sensor, a method of processing said first and further sensor output signals to reduce the noise components in said first sensor output signals and thereby derive noise-reduced estimates of each of the information components within said first sensor output signals, said method comprising the steps of:
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(a) generating a first signal, representative of the information component within said further image sensor signal, as a function of said first sensor output signals; (b) generating a plurality of second signals representative of the noise variances associated with the operation of said first image sensors and said further image sensor; and (c) combining the first and further sensor output signals produced by said first and further image sensors, respectively, with said first signal generated in step (a) and said plurality of second signals generated in step (b), to obtain said noise-reduced estimates of the information components of each of the information components within said first sensor output signals. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. For use with a multiple color image sensor system having a plurality of first image sensors, each of which produces a respective first sensor output signal that contains a respective color representative component of an image and a noise component associated with the operation of a sensor through which its output signal is produced, and a further image sensor that produces a further sensor output signal containing a luminance representative component of said image, and which is expressible as a function of color components of said first sensor output signals, and a noise component associated with the operation of said further image sensor, a method of processing said first and further sensor output signals to reduce the noise components in said first sensor output signals and thereby derive noise-reduced estimates of each of the color components of said first sensor output signals comprising the steps of:
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(a) generating a first signal, representative of said further image sensor signal, as a function of said first sensor output signals; (b) generating a second signal representative of a prescribed relationship between said first signal and said further sensor output signal; and (c) combining the first sensor output signals produced by said first image sensors with said second signal generated in step (b), to obtain said noise-reduced estimates of the color components of each of said first sensor output signals. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification