VisQI: A Visual Analysis Tool for the Debugging of Quantum Image Processing Algorithms

Abstract Quantum Image Processing (QIMP) offers a promising approach for handling image data. Specifically, the Novel Enhanced Quantum Representation (NEQR) for images enables the execution of operations on all pixels of the image simultaneously. However, due to the currently high costs and the limited performance of quantum hardware, algorithm development relies on simulators and is prone to errors when implementing quantum gates for image encoding and processing. The quantum nature of images, where each pixel's colour is represented by a probability distribution, further complicates debugging of respective algorithms. In this design study, we present VisQI, an interactive visualization tool tailored to analyzing and debugging QIMP algorithms that encode and process NEQR images. VisQI integrates several visualization techniques to provide both a holistic view regarding the evolution of images subjected to quantum gate operations as well as detailed insights into the colour probability distributions of processed pixels. A qualitative user study involving seven QIMP developers demonstrated that VisQI significantly improves understanding of how individual gate operations affect an image. Participants appreciated the tool's ability to facilitate a step‐by‐step analysis and error identification. Our results highlight the critical role of advanced visualization in the development of QIMP algorithms to pave the way for future improvements in quantum image analysis.