1. A parameter determination assisting device for an image processing device configured to obtain a processing result by performing a process using a set of parameters defined in advance on image data obtained by imaging a measuring target object, the parameter determination assisting device comprising: an input unit configured to accept the image data and an expected result corresponding to the image data, wherein the expected results each includes an expected class indicating whether the corresponding measuring target object is a non-defective article or a defective article; a candidate generation unit configured to generate a plurality of parameter candidates in which at least one parameter value contained in the set of parameters is different from each other, wherein at least one of the plurality of the parameter candidates is length of processing time; an acquiring unit configured to acquire a plurality of processing results respectively using the plurality of parameter candidates on the image data according to a condition; an evaluation unit configured to generate an evaluation result for each of the plurality of processing results by comparing each of the plurality of processing results with the corresponding expected result; and an output unit configured to output the evaluation result for each of the plurality of parameter candidates, wherein the input unit is configured to accept the plurality of image data respectively acquired from a plurality of measuring target objects and the expected results respectively corresponding to the plurality of image data, and the acquiring unit is configured to acquire a processing result group including the evaluation results on the plurality of image data for the plurality of parameter candidates respectively, the acquiring unit includes: a portion configured to calculate a characteristic amount on the image data by performing the process on the image data; and a portion configured to generate the processing result by comparing the characteristic amount with a threshold value provided in advance, and the output unit is configured to output the condition; output the evaluation result with a mark indicating a match between the processing result and the expected result in a different manner from a mark indicating a mismatch between the processing result and the expected result; and output an area for displaying the mark indicating the match between the processing result and the expected result in a different manner from another area.