Method and apparatus for enhancing sharpness of a sequence of images subject to continuous zoom
AssigneeEastman Kodak Company
InventorsJennifer C. Loveridge, Richard A. Sharman
Life of this patent
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Abstract
A bandpass enhancement filter has a pass-band that tracks changes in spatial frequency due to the use of a zooming process upon a digital image signal. The primary pass-band of the enhancement filter is derived from a combination of a plurality of secondary bandpass filter sections, each having a different frequency response and each responsive to a gain adjustment. A control signal reflecting a particular zoom ratio is used in the adjustment of the gain applied to the filter sections, thereby proportioning the output of each filter section so that the combined output tracks the zooming process.
Claims15
Apparatus for enhancing the sharpness of an image signal subject to a zooming process that changes the spatial frequency of the image signal, said apparatus comprising:
- means for generating the image signal;
- means for generating a control signal indicative of the amount of zoom performed on the image signal;
- means for enhancing the image signal, said enhancing means operative within a primary pass-band derived from a plurality of different pass-bands each responsive to a gain adjustment;
- and
- means responsive to the control signal for adjusting the gain applied to the different pass-bands according to a predetermined function of the amount of zoom performed on the image signal, whereby the primary pass-band of said enhancing means tracks changes in the spatial frequency of the image signal due to the zooming process.
Apparatus for filtering a digital image signal subject to a zooming process that changes the spatial frequency of the digital image signal, said apparatus comprising:
- means for generating the digital image signal;
- means for generating a ratio signal indicative of the amount of zoom performed on the image signal;
- filtering means for processing the digital image signal to enhance the digital image signal, said filtering means having a primary bandpass characteristic derived from a predetermined combination of a plurality of secondary bandpass filter sections, each operative upon the digital image signal and each responsive to a gain adjustment;
- means responsive to said ratio signal for adjusting the gain applied to said bandpass filter sections to thereby effect said predetermined combination, whereby the pass-band of said filtering means tracks changes in the spatial frequency of the digital image signal due to zooming.
Method for enhancing the sharpness of an image signal subject to a zooming process that changes the spatial frequency of the image signal, said method comprising the steps of:
- generating the image signal;
- generating a control signal indicative of the amount of zoom performed on the image signal;
- providing a plurality of bandpass filters having different pass-bands;
- proportioning the response of each of the bandpass filters in response to the magnitude of the control signal;
- and
- summing the proportioned response of each of the bandpass filters to thereby form a composite bandpass filter having a band edge that tracks changes in the spatial frequency of the image signal due to the zooming process.
Dependencies are inferred from the claim text.