System and Method For Improving Graphics And Other Signal Results Through Signal Transformation And Application of Dithering
AssigneeApple Inc.
InventorsKenneth I. Greenebaum, Eric L. Dacquay, Ian C. Hendry
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Abstract
Systems, methods, and computer readable media are described for effectively using dither techniques upon signals having a predicted quantization error that varies across the range of the signal. In some embodiments, predicted error is used to shape a precision input signal so that the newly-shaped signal yields a uniform or relatively uniform predicted quantization error. A dither is applied to the re-shaped signal, and the shaping is reversed, after which the signal may be slope limited and/or quantized, taking full and efficient advantage of the dithering technique.
Claims20
A method comprising:
- receiving a first precision signal;
- determining a second precision-limited signal based upon the first precision signal;
- determining inverse error information based upon a comparison of the first precision signal and the second precision-limited signal, wherein the inverse error information reflects an inverse of an error between the first precision signal and the second precision-limited signal;
- transforming the first precision signal by combining the first precision signal with the inverse error information to form an error-transformed precision signal;
- applying dithering to the error-transformed precision signal;
- forming a third precision signal by applying a reverse transform to the dithered error-transformed precision signal;
- and
- creating a fourth precision-limited version of the third precision signal.
A method comprising:
- receiving a first precision signal;
- generating a plurality of values of a second precision-limited signal by application of a lookup table (LUT), the values of the second precision-limited signal reflecting:
- a calculation of predicted error caused by a quantization of the first precision signal,
- an application of dithering to an error-transformed version of the first precision signal, wherein the error-transformed version of the first precision signal reflects a combination of the predicted error with the first precision signal, and
- a reverse error-transformation of the dithered error-transformed version of the first precision signal, wherein the reverse error-transformation reflects an inversion of the combination of the predicted error with the first precision signal;
- and
- generating values of a quantized version of the second precision-limited signal.
A computer readable medium comprising one or more instructions that, when executed, configure a processor to:
- receive a first precision signal;
- generate a plurality of values of a second precision-limited signal by application of a lookup table (LUT), the values of the second precision-limited signal reflecting:
- a calculation of predicted error caused by a quantization of the first precision signal;
- an application of dithering to an error-transformed version of the first precision signal, wherein the error-transformed version of the first precision signal reflects a combination of the predicted error with the first precision signal;
- a reverse error-transformation of the dithered error-transformed version of the first precision signal, wherein the reverse error-transformation reflects an inversion of the combination of the predicted error with the first precision signal;
- and
- generate values of a quantized version of the second precision-limited signal.
Dependencies are inferred from the claim text.