Image encoding methods and apparatus providing improved visual results
AssigneeAccusoft Corporation
InventorThomas Richter
Life of this patent
Estimating the term…
Abstract
Microsoft's recently proposed new image compression codec JPEG XR is currently undergoing ISO standardization as JPEG-XR. Even though performance measurements carried out by the JPEG committee indicated that the PSNR performance of JPEG XR is competitive, the visual performance of JPEG XR showed notable deficits, both in subjective and objective tests. This paper introduces various techniques that improve the visual performance of JPEG XR without leaving the current codestream definition. Objective measurements performed by the author indicate that the modified encoder, while staying backwards compatible to the current standard proposition, improves visual performance significantly, and the performance of the modified encoder is similar to JPEG.
Claims19
An image processing method, the method comprising:
- receiving quantized transform coefficients corresponding to an image;
- estimating an amount of image distortion resulting if at least one quantized transform coefficient is modified;
- predicting quantized transform coefficient reordering prior to performing an entropy encoding operation;
- determining a threshold as a function of the predicted quantized transform coefficient reordering;
- comparing the estimated amount of image distortion to said threshold;
- and
- selectively modifying said at least one quantized transform coefficient value when said threshold is not exceeded.
An image processing method, the method comprising:
- receiving quantized transform coefficients corresponding to an image;
- estimating an amount of image distortion resulting if at least one s quantized transform coefficient is modified;
- comparing the estimated amount of image distortion to a threshold;
- and
- selectively modifying said at least one quantized transform coefficient value when said threshold is not exceeded;
- wherein said at least one individual quantized transform coefficient includes residual bits and high order bits;
- and
- wherein said selectively modifying said at least one quantized transform coefficient includes setting the high order bits to represent a value of:
- one or minus one.
An image processing system, comprising:
- means for receiving quantized transform coefficients corresponding to an image;
- means for predicting quantized transform coefficient reordering;
- and
- means for selectively modifying quantized transform coefficients based on the predicted quantized transform coefficient reordering.
A non-transitory computer readable medium embodying computer readable instructions for controlling an image processing apparatus, the non-transitory computer readable medium comprising:
- instructions for causing said apparatus to receive quantized transform coefficients corresponding to an image;
- instructions for causing said apparatus to estimate an amount of image distortion resulting if at least one quantized transform coefficient is modified;
- instructions for causing said apparatus to predict quantized transform coefficient reordering prior to performing an entropy encoding operation;
- instructions for causing said apparatus to determine a threshold as a function of the predicted quantized transform coefficient reordering;
- instructions for causing said apparatus to compare the estimated amount of image distortion to said threshold;
- and
- instructions for causing said apparatus to selectively modify said at least one quantized transform coefficient value when said threshold is not exceeded.
Dependencies are inferred from the claim text.