VIDEO PROCESSING USING A ONE-DIMENSIONAL CONTROL FUNCTION TO CONTROL COST AND ERROR

1 . A method of defining a one-dimensional control function for controlling a process in a data processor in order to affect outcomes of processing cost and processing error, the method comprising the steps of:

generating, via the data processor, points in error/cost space corresponding to multiple combinations of parameter values applied to reference input data applied to the process,

selecting, via the data processor, a subset of points in which each point is such that all other points in the space have either a higher error or a higher cost, and

associating, via the data processor, with the values of a control variable only those combinations of parameter values corresponding to the selected subset,

so that a control variable value applied to the one-dimensional control function causes the respective associated combination of parameter values to be applied to the process.

2 . The method according to claim 1 in which error/cost gradients of lines between adjacent points in the subset form a monotonically increasing or decreasing sequence.

3 . The method according to claim 1 in which the subset is modified so that the values of each parameter are individually monotonically increasing or decreasing with respect to error or to cost.

4 . A method of controlling a process in a data processor, the method comprising the steps of:

providing a one dimensional control function which affects outcomes of processing cost and processing error in response to an applied control variable; and

applying the control variable to the control function,

where the values of the control variable are associated in the control function with selected sub-sets of control parameters for the process so that increasing values of the control variable result in monotonically decreasing process errors and monotonically increasing cost to process a given volume of input data.

5 . The method according to claim 4 in which the control function is defined by

generating points in error/cost space corresponding to multiple combinations of parameter values applied to reference input data applied to the process,

selecting a subset of points in which each point is such that all other points in the space have either a higher error or a higher cost, and

associating with the values of a control variable only those combinations of parameter values corresponding to the selected subset,

so that a control variable value applied to the one-dimensional control function causes the respective associated combination of parameter values to be applied to the controlled process.

6 . The method according to claim 4 in which a property is estimated from incoming data and the said control variable is selected according to the value of the property.

7 . The method according to claim 6 in which the incoming data is divided into segments and, for each segment of incoming data, an estimate of the local error/cost function for that segment is made and the control effected to equalize the gradient of the function across all segments by changing the value of the control variable.

8 . The method according to claim 7 in which the value of said equalised gradient is chosen according a required processing time for a given input to the process.

9 . The method according to claim 7 in which the value of said equalised gradient is chosen in dependence on a required total error in the output from the process.

10 . (canceled)

11 . Video processing apparatus comprising

a processing block receiving a video input and a control value;

an activity detector providing a measure of activity in the video input; and

a controller which receives the measure of activity and derives therefrom the control value in accordance with a control function, wherein the control function is derived by

generating points in error/cost space corresponding to multiple combinations of parameter values applied to reference video data,

selecting a subset of points in which each point is such that all other points in the space have either a higher error or a higher cost,

associating with the values of a control variable only those combinations of parameter values corresponding to the selected subset,

so that a control variable value applied to the one-dimensional control function causes the respective associated combination of parameter values to be applied to the video input.

12 . The apparatus according to claim 11 in which the error/cost gradients of lines between adjacent points in the subset form a monotonically increasing or decreasing sequence.

13 . The apparatus according to claim 11 in which the subset is modified so that the values of each parameter are individually monotonically increasing or decreasing with respect to error or to cost.

14 . A non-transient computer program product adapted to cause programmable apparatus to implement a method of defining a one-dimensional control function for controlling a process performed in a data processor in order to affect outcomes of processing cost and processing error, the method implemented by the programmable apparatus and comprising the steps of:

generating points in error/cost space corresponding to multiple combinations of parameter values applied to reference input data applied to the process,

selecting a subset of points in which each point is such that all other points in the space have either a higher error or a higher cost, and

associating with the values of a control variable only those combinations of parameter values corresponding to the selected subset,

so that a control variable value applied to the one-dimensional control function causes the respective associated combination of parameter values to be applied to the process.