Device and method for applying a look-up table

Patent metadata

Field	Value
Publication number	US-12231122-B2
Application number	US-202118025078-A
Country	US
Kind code	B2
Filing date	Sep 6, 2021
Priority date	Sep 8, 2020
Publication date	Feb 18, 2025
Grant date	Feb 18, 2025

Abstract

A device applies a pre-function w=P(x) to an input signal x to obtain a first result w and applies a LUT to the first result w, wherein the LUT represents a main function ƒ w (w) defined for a second grid of values Gw such that the pre-function P(x) is piecewise defined on a first grid Gx of signal values, where Gw=P(Gx). The device can further obtain the pre-function P(x), piecewise defined on the first grid Gx of the signal x and calculate the LUT with the second grid Gw=P(Gx). The piecewise pre-function P(x) can be obtained from a second pre-function Q(x) by applying Q(x) to signal values x to calculate the second grid Gw=Q(Gx) and defining the pre-function P(x) piecewise on the first grid Gx by linear interpolation of the values of the second grid Gw such that P(Gx)=Q(Gx).

First claim

The invention claimed is:

1. A method, performed in a device and comprising:
applying a pre-function w=P(x) to an input signal x to obtain a first result w; and
applying a look up table (LUT) to the first result w, wherein the LUT represents a main function ƒ w (w) defined for a second grid of values Gw such that the pre-function P(x) is piecewise defined on a first grid Gx of signal values, where Gw=P(Gx), and
wherein the pre-function P(x) is obtained from a second pre-function Q(x) by applying Q(x) to signal values x to calculate the second grid Gw=Q(Gx) and defining the pre-function P(x) piecewise on the first grid Gx by linear interpolation of the values of the second grid Gw such that P(Gx)=Q(Gx).

2. The method of claim 1 , wherein the signal x is n-dimensional and the pre-function P(x) is applied to less than all the n dimensions of the signal x.

3. The method of claim 1 , further comprising:
obtaining the pre-function P(x), piecewise defined on the first grid Gx of the signal x; and
calculating the LUT with the second grid Gw=P(Gx).

4. The method of claim 1 , wherein the LUT is calculated by:
concatenating an inverse function P −1 (w) of the pre-function P(x) and a second main function f(x) to obtain the main function ƒ w (w) as concatenated function ƒ w (w)=f(P −1 (w)); and
sampling the concatenated function over the second grid Gw.

5. The method of claim 4 , wherein the pre-function P(x) is obtained by:
for at least one piece of the pre-function P(x), analysing a curvature of the second main function f(x) in at least one interval that corresponds to the piece of the pre-function P(x);
modifying a shape of the pre-function P(x) for the at least one piece according to the shape of the second main function f(x);
for the interval of values x that correspond to the at least one piece, calculating a LUT application error; and
iterating until the LUT application error is less than a given value.

6. A device comprising:
memory configured to store processor-executable program code instructions; and
at least one hardware processor configured to execute the program code instructions to:
apply a pre-function w=P(x) to an input signal x to obtain a first result w; and
apply a look up table (LUT) to the first result w, wherein the LUT represents a main function ƒ w (w) defined for a second grid of values Gw such that the pre-function P(x) is piecewise defined on a first grid Gx of signal values, where Gw=P(Gx), and
wherein the pre-function P(x) is obtained from a second pre-function Q(x) by applying Q(x) to signal values x to calculate the second grid Gw=Q(Gx) and defining the pre-function P(x) piecewise on the first grid Gx by linear interpolation of the values of the second grid Gw such that P(Gx)=Q(Gx).

7. The device of claim 6 , wherein the signal x is n-dimensional and the pre-function P(x) is applied to less than all the n dimensions of the signal x.

8. The device of claim 6 , wherein the at least one hardware processor is further configured to execute the program code instructions to:
obtain the pre-function P(x), piecewise defined on the first grid Gx of the signal x; and
calculate the LUT with the second grid Gw=P(Gx).

9. The device of claim 6 , wherein the LUT is calculated by:
concatenating an inverse function P −1 (w) of the pre-function P(x) and a second main function f(x) to obtain the main function ƒ w (w) as concatenated function ƒ w (w)=f(P −1 (w)); and
sampling the concatenated function over the second grid Gw.

10. The device of claim 9 , wherein the pre-function P(x) is obtained by:
for at least one piece of the pre-function P(x), analysing a curvature of the second main function f(x) in at least one interval that corresponds to the piece of the pre-function P(x);
modifying a shape of the pre-function P(x) for the at least one piece according to the shape of the second main function f(x);
for the interval of values x that correspond to the at least one piece, calculating a LUT application error; and
iterating until the LUT application error is less than a given value.

11. A non-transitory computer readable medium storing program code instructions that, when executed by a processor, implement a method comprising:
applying a pre-function w=P(x) to an input signal x to obtain a first result w; and
applying a look up table (LUT) to the first result w, wherein the LUT represents a main function ƒ w (w) defined for a second grid of values Gw such that the pre-function P(x) is piecewise defined on a first grid Gx of signal values, where Gw=P(Gx), and
wherein the pre-function P(x) is obtained from a second pre-function Q(x) by applying Q(x) to signal values x to calculate the second grid Gw=Q(Gx) and defining the pre-function P(x) piecewise on the first grid Gx by linear interpolation of the values of the second grid Gw such that P(Gx)=Q(Gx).

12. The non-transitory computer readable medium of claim 11 , wherein the signal x is n-dimensional and the pre-function P(x) is applied to less than all the n dimensions of the signal x.

13. The non-transitory computer readable medium of claim 11 , wherein the program code instructions that, when executed by a processor, implement a method that further comprises:
obtaining the pre-function P(x), piecewise defined on the first grid Gx of the signal x; and
calculating the LUT with the second grid Gw=P(Gx).

14. The non-transitory computer readable medium of claim 11 , wherein the program code instructions that, when executed by a processor, implement a method that further comprises calculating the LUT by:
concatenating an inverse function P −1 (w) of the pre-function P(x) and a second main function f(x) to obtain the main function ƒ w (w) as concatenated function ƒ w (w)=f(P −1 (w)); and
sampling the concatenated function over the second grid Gw.

15. The non-transitory computer readable medium of claim 14 , wherein the program code instructions that, when executed by a processor, implement a method that further comprises obtaining the pre-function P(x) by:
for at least one piece of the pre-function P(x), analysing a curvature of the second main function f(x) in at least one interval that corresponds to the piece of the pre-function P(x);
modifying a shape of the pre-function P(x) for the at least one piece according to the shape of the second main function f(x);
for the interval of values x that correspond to the at least one piece, calculating a LUT application error; and
iterating until the LUT application error is less than a given value.

Assignees

• Interdigital Ce Patent Holdings Sas

Inventors

• Stauder Jurgen
• Mazzante Angelo
• Colaitis Marie-Jean
• Morvan Patrick

Classifications

• H03K19/17728 Primary

  Reconfigurable logic blocks, e.g. lookup tables · CPC title

• H04N1/6019 Primary

  using look-up tables (H04N1/6025 takes precedence) · CPC title