1. An image processing software development method that assists the development of software using a programming language library for an image processing device and is executed on an image processing software development device, wherein the image processing software development device includes a storage device and a control device for configuring a model diagram editing section, wherein the storage device includes a component diagram definition section to store an input/output data memory management component diagram, an input data value setup component diagram, a library execution component diagram, and an output data value acquisition component diagram as four types of lower-level component diagrams, which are elements of a model diagram descriptive of software; wherein the lower-level component diagrams include a function of the programming language library and connection terminals for specifying the input/output data for executing the function, wherein the storage device further stores upper-level component diagrams that are obtained by grouping the four types of lower-level component diagrams, which are connected through the connection terminals, and wherein the model diagram editing section prepares the model diagram by, upon receipt of an operation for adding the lower-level component diagrams or the upper-level component diagrams to the model diagram, adding the associated lower-level component diagrams or the associated upper-level component diagrams to the model diagram, and by, upon receipt of an operation for connecting the connection terminals of the lower-level component diagrams, connecting the associated connection terminals with a directional link.