Patent ID: 8531744

Claim:
An image defect diagnostic system comprising: a memory that stores an image density threshold set for each of partial regions in a test target image being a test target for an image defect and set as a criteria for judging whether or not each of the partial regions has an image defect, and that stores a positional information piece indicating a position of corresponding one of the partial regions in the test target image, while associating the image density threshold and the positional information piece with each other; a diagnostic unit that compares an image data piece of each of the partial regions generated by scanning the test target image with the image density threshold set for corresponding one of the partial regions stored in the memory, to diagnose whether or not an image defect occurs in the test target image; an image scanner unit that scans a threshold calculation image for calculating the image density threshold to be stored in the memory, and that detects tone density values of pixels forming the threshold calculation image; and a threshold setting unit that sets, as the image density threshold for the threshold calculation image, one tone density value obtained at a time when, by using the one tone density value as a variable, a ratio of an area occupied by a region formed of pixels each having a tone density value not less than the one tone density value to an area of the threshold calculation image becomes a value set in advance, the pixels forming the threshold calculation image scanned by the image scanner unit.