Aiming at the problems of the separation of brush stroke rendering and aesthetic evaluation, the lack of local texture control and the lag of interactive response in digital painting system, a digital painting system architecture combining computer graphics and aesthetic optimization was designed. The system encodes stroke geometry, layer state, color distribution, composition structure and texture response as fusion features, and constructs stroke cover calculation, texture perturbation rendering, aesthetic score feedback and local incremental update mechanisms. The experimental results show that the FPS of our system reaches 58.7, the average delay is 24.6 ms, the SSIM reaches 0.902, and the LPIPS is reduced to 0.118. After Aesthetic optimization, the aesthetic scores of oil painting, watercolor, ink painting and sketch samples are increased to 8.61, 8.42, 8.36 and 8.29, respectively. Ablation experiments show that the aesthetic optimization module contributes the most to the score improvement, and the local update module can significantly reduce the interaction delay. The research can provide technical reference for real-time generation and picture quality optimization of digital painting system.
