SSIM (Structural Similarity Index Measure) compares two images by evaluating luminance, contrast, and structural patterns across local windows. It returns a score from -1 to 1: 1.0 means the images are pixel-identical, 0 means no structural correlation, and negative values mean the images are anti-correlated (less alike than random noise). For glyph comparison, it answers the question: do these two rendered characters share the same visual structure?
先理解原理：看动图 + 手动模拟小数组
，详情可参考WPS官方版本下载
The number of data centres, like this Google facility in Hertfordshire, is increasing
这背后，是当地日益增长的医疗压力——老人的需求变复杂了，医院必须跟着升级，才能接住这些需求。