PURPOSE: To obtain test data to be displayed only by specifying the original picture data of test data to be formed and an attribute relating to the original picture data by providing the system with a synthesizing mechanism for synthesizing the specified original picture data with the specified attribute.

CONSTITUTION: An original picture data selecting mechanism 10 selects original picture data to be formed from data stored in an original picture data storing means 10a based upon an instruction from an external input device 100 and an attribute selecting mechanism 20 selects an attribute element relating to the selected original picture data from the data stored in an attribute storing means 20a. The synthesizing means 30 synthesizes the selected original picture data and attribute element and a test data forming mechanism adds a parameter necessary for display to the synthesized data to form display enabled test data, displays the test data and stores the test data in a test data storing means 50 if necessary. Consequently, the original picture data and its attribute element can be automatically synthesized by an engineering work station and the working efficiency can be improved.