Hui Wang 0086 Qingxin Xia Boling Wang Jianglan Huang An Experimental Research of image enhancement for old Grayscale photos of China. 535-539 2023 EITCE https://doi.org/10.1145/3650400.3650488 conf/eitce/2023 db/conf/eitce/eitce2023.html#WangXWH23