A translator receives a source code that is described using a process designation (such as a line-by-line process designation, a line data extraction designation, and a broadcast designation) to be performed on line data of an image on a line by line basis, parses and optimizes the source code, and then generates an SIMD macro code that is an intermediate form taking into consideration the use of an SIMD instruction set. A simplifier generates, from the SIMD macro code, a simplified SIMD macro code, namely, a composite macro code into which a series of codes having the relationship between the definition and the reference of the same virtual SIMD register is organized. A machine code generator generates, from the simplified SIMD macro code, a machine code that efficiently uses an SIMD instruction.