1. A computer-implemented method for coding a block of pixels of a digitized video image using a selectable one of a plurality of coding functions, comprising the steps of: establishing adjustable selection criteria for selecting a coding function; measuring a predetermined characteristic of the block to obtain a characteristic value; selecting a coding function based on said selection criteria and said characteristic value; coding the block according to said coding function from said selecting step to obtain a coded block; performing a quality measurement of said coded block; and adjusting said selection criteria based on said quality measurement, whereby quality measures of subsequent blocks are improved through adjusted selection criteria for selecting coding functions.