Metamorphic relations based test oracles for image processing applications

Evaluation of output images carrying visual semantics is a challenging task which is carried out by domain experts through visual inspection. Automatic test oracle is required to augment the test oracle problem and to eliminate the manual efforts. Metamorphic testing is an effective technique to alleviate these problems. In this paper, the authors have demonstrated that how inherent properties of implementation under test can be used to generate an automatic test oracle for image processing applications. Metamorphic testing is a general technique in which follow-up test cases are generated using a transformation function and the anticipated output is evaluated. They have used some general metamorphic relations and also designed some algorithm specific metamorphic relations for morphological image operations. Selection of metamorphic relations is the most important step and the authors have analyzed relative effectiveness of different metamorphic relations using mutation analysis. The results show metamorphic testing is a very effective technique to automate output images evaluation and to alleviate oracle problem.