D. I. Mulyana and M. A. A. Abyan, “Image Quality Improvement for Sign Language Gestures Through Gaussian Filter and Contrast Stretching Techniques”, Int. J. Softw. Eng. Comput. Sci., vol. 5, no. 3, pp. 1029–1044, Dec. 2025, doi: 10.35870/ijsecs.v5i3.5254.