System and method for quality-aware selection of parameters in transcoding of digital images

A system for quality-aware transcoding of 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;
• a non-transitory computer readable storage medium having computer executable instructions stored thereon for execution by the processor, causing the processor to:
• (a) extract features of the input image including dimensions and a file size of the input image;
• (b) predict, from file size prediction information obtained by 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, from quality metric prediction information obtained by transcoding the set of training images, predicted quality metric (QM) values of the output image, characterizing a predicted measure of distortion of the input image introduced by the transcoding, corresponding to the feasible transcoding parameters in the set of feasible transcoding parameters;
• the quality metric prediction information being determined explicitly by a comparison between input images from the set of training images and corresponding output images resulting from the transcoding 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.

A system for quality-aware transcoding of 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 non-transitory computer readable storage medium having computer executable instructions stored thereon for execution by the processor, forming:
• (a) a means for extracting features of the input image including dimensions and a file size of the input image;
• (b) a means for predicting, from file size prediction information obtained by transcoding of 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) a means for determining, from quality metric prediction information obtained by transcoding of the 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 the transcoding, corresponding to the feasible transcoding parameters in the set of feasible transcoding parameters;
• the quality metric prediction information being determined explicitly by a comparison between input images from the set of training images and corresponding output images resulting from the transcoding of the set of training images;
• and
• (d) a means for 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.