1. A linear transform apparatus for implementing a linear transform on input data values to produce linear transformed output data, the apparatus comprising: input means for inputting input data values one after another to each of a series of multiplication means; a series of multiplication means interconnected with said input means for multiplying a current input data value by a constant to produce a current multiplier output; an interconnection network interconnecting said series of multiplication means to predetermined ones of a series of signed accumulator means; series of signed accumulator means each interconnected to said interconnection network, each of said signed accumulator means producing an intermediate accumulator output by accumulating a corresponding one of said current multiplier outputs with a corresponding previous intermediate accumulator output, each of said signed accumulator means outputting said intermediate accumulator output as a corresponding linear transformed output data value.