System and method for quality-aware selection of parameters in transcoding of digital images
First Claim
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1. A method for transcoding an input image into an output image for display on a terminal having device file size and image size constraints, the method comprising:
- (a) extracting features of the input image including dimensions and a file size of the input image;
(b) predicting, from transcoding a set of training images, a file size of the output image taking into account the constraints of the terminal and the extracted features, comprising selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal;
(c) determining predicted quality metric (QM) values of the output image, the predicted QM values characterizing a predicted measure of distortion of the input image introduced by transcodings, corresponding to various feasible transcoding parameters in the set of feasible transcoding parameters;
the predicted QM values being determined by a comparison between the input image and corresponding output images resulting from the transcodings;
the predicted QM values being further determined based on viewing conditions, comprising respective resolutions at which the input image and the corresponding output images have been scaled for determining the predicted QM values; and
(d) selecting those transcoding parameters from the set of feasible transcoding parameters, which yield the highest predicted QM value, corresponding to the highest predicted visual quality for the output image for the set of feasible transcoding parameters.
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Abstract
Several quality-aware transcoding systems and methods are described, in which the impact of both quality factor (QF) and scaling parameter choices on the quality of transcoded images are considered in combination. A basic transcoding system is enhanced by the addition of a quality prediction look-up table, and a method of generating such a table is also shown.
29 Citations
38 Claims
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1. A method for transcoding an input image into an output image for display on a terminal having device file size and image size constraints, the method comprising:
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(a) extracting features of the input image including dimensions and a file size of the input image; (b) predicting, from transcoding a set of training images, a file size of the output image taking into account the constraints of the terminal and the extracted features, comprising selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal; (c) determining predicted quality metric (QM) values of the output image, the predicted QM values characterizing a predicted measure of distortion of the input image introduced by transcodings, corresponding to various feasible transcoding parameters in the set of feasible transcoding parameters; the predicted QM values being determined by a comparison between the input image and corresponding output images resulting from the transcodings; the predicted QM values being further determined based on viewing conditions, comprising respective resolutions at which the input image and the corresponding output images have been scaled for determining the predicted QM values; and (d) selecting those transcoding parameters from the set of feasible transcoding parameters, which yield the highest predicted QM value, corresponding to the highest predicted visual quality for the output image for the set of feasible transcoding parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for transcoding an input image into an output image for display on a terminal having device file size and image size constraints, the system comprising:
a processor, and a memory device, having computer readable instructions stored thereon for execution by a processor, the processor being configured to; (a) extract features of the input image including dimensions and a file size of the input image; (b) predict, from transcoding a set of training images, a file size of the output image taking into account the constraints of the terminal and the extracted features, comprising selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal; (c) determine predicted quality metric (QM) values of the output image, the predicted QM values characterizing a predicted measure of distortion of the input image introduced by transcodings, corresponding to various feasible transcoding parameters in the set of feasible transcoding parameters; the predicted QM values being determined by a comparison between the input image and corresponding output images resulting from the transcodings; the predicted QM values being further determined based on viewing conditions, comprising respective resolutions at which the input image and the corresponding output images have been scaled for determining the predicted QM values; and (d) select those transcoding parameters from the set of feasible transcoding parameters, which yield the highest predicted QM value, corresponding to the highest predicted visual quality for the output image for the set of feasible transcoding parameters. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for transcoding of an input image into an output image for display on a terminal having device file size and image size constraints, the method comprising:
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(a) extracting features of the input image including dimensions and a file size of the input image; (b) predicting a file size of the output image taking into account the constraints of the terminal and the extracted features, comprising selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal; (c) determining, from transcoding a set of training images, predicted quality metric (QM) values of the output image, the predicted QM values characterizing a predicted measure of distortion of the input image introduced by transcodings, corresponding to various feasible transcoding parameters in the set of feasible transcoding parameters; the predicted QM values being determined by comparison between input images from the set of training images and corresponding output images resulting from the transcodings of the set of training images; and (d) selecting those transcoding parameters from the set of feasible transcoding parameters, which yield the highest predicted QM value, corresponding to the highest predicted visual quality for the output image for the set of feasible transcoding parameters. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A system for transcoding an input image into an output image for display on a terminal having device file size and image size constraints, the system comprising:
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a processor, and a memory device, having computer readable instructions stored thereon for execution by a processor, the processor being configured to; (a) extract features of the input image including dimensions and a file size of the input image; (b) predict a file size of the output image taking into account the constraints of the terminal and the extracted features, comprising selecting a set of feasible transcoding parameters so that a corresponding predicted file size of the output image meets the device file size constraint of the terminal; (c) determine, from transcoding a set of training images, predicted quality metric (QM) values of the output image, the predicted QM values characterizing a predicted measure of distortion of the input image introduced by transcodings, corresponding to various feasible transcoding parameters in the set of feasible transcoding parameters; the predicted QM values being determined by comparison between input images from the set of training images and corresponding output images resulting from the transcodings of the set of training images; and (d) select those transcoding parameters from the set of feasible transcoding parameters, which yield the highest predicted QM value, corresponding to the highest predicted visual quality for the output image for the set of feasible transcoding parameters. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38)
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Specification