Digital Signal Processing Methods and Apparatus

Apparatus for digitally processing data in a data array defining a target matrix (X) using non-negative matrix factorisation to determine a pair of matrices (F, G), a first matrix of said pair determining a set of features for representing said data, a second matrix of said pair determining weights of said features, such that a product of said first and second matrices approximates said target matrix, the apparatus comprising:

• means for inputting said target matrix data (X);
• means for selecting a row of said one of said first and second matrices and a column of the other of said first and second matrices;
• means for determining a target contribution (R) of said selected row and column to said target matrix;
• means for determining, subject to a non-negativity constraint, updated values for said selected row and column from said target contribution;
• and
• means for repeating said selecting and determining for the other rows and columns of said first and second matrices until all said rows and columns have been updated.

A method of driving an electro-optic display, the display having a matrix of pixels, the method comprising:

• inputting image data for said matrix of pixels into an image data matrix;
• factorising said image data matrix into a product of first and second factor matrices;
• and
• driving said display using said factor matrices;
• and wherein
• said factorising comprising iteratively adjusting said factor matrices such that their product approaches said image data matrix;
• and wherein
• said iterative adjusting comprises adjusting each row of one of said factor matrices and each column of the other of said factor matrices in turn.

A driver for an electro-optic display, the display having a matrix of pixels, the driver comprising:

• an input to input image data for said matrix of pixels into an image data matrix;
• a matrix factorisation system to factorise said image data matrix into a product of first and second factor matrices;
• and
• a driver output to drive said display using said factor matrices, and wherein
• said matrix factorisation system is configured to iteratively adjust said factor matrices, such that their product approaches said image data matrix, by adjusting each row of one of said factor matrices and each column of the other of said factor matrices in turn.

A method of processing a data array defining a target matrix (X) to determine a pair of factor matrices (F,G) such that a product of said factor matrices approximates said target matrix (X), the method comprising:

• determining for a single row or column of a first said factor matrix a value to which an updating rule would converge when iteratively applied, said updating rule comprising an updating rule of a factorising algorithm which iteratively updates two factor matrices to more closely approximate a target matrix using said updating rule;
• updating said row or column with said determined value;
• repeating said determining and updating for a column or row of a second said factor matrix;
• and
• repeating said determining and updating of said first and second factor matrices to update each row or column of said first factor matrix and each column or row of said second factor matrix.