1. An image data processing apparatus, comprising: a buffer memory unit for storing multi-valued image data and for outputting the stored image data on a pixel basis, the image data having image data groups of pixel matrices, each of the pixel matrices becoming a current pixel matrix when a centrally located pixel in the pixel matrix becomes a current pixel; a processing unit connected to said buffer memory unit including a plurality of processor elements each processing the image data having a range of bit widths, said processor elements concurrently processing the image data; and a control information memory unit connected to said processing unit and said buffer memory unit for storing reference data for pattern matching and control data, each of said processor elements binarizing a corresponding one of the image data groups based upon a predetermined threshold value, said processing unit converting the binarized image data into a one-dimensional serial image data of a predetermined bit width, said processor elements comparing the converted imaged data to the reference data in said control information memory unit to generate a determination result.