// 易错点4：栈空时要存-1（题目要求无更大值返回-1），而非直接存stack2.at(-1)（会得到undefined）
Another way to approach dithering is to analyse the input image in order to make informed decisions about how best to perturb pixel values prior to quantisation. Error-diffusion dithering does this by sequentially taking the quantisation error for the current pixel (the difference between the input value and the quantised value) and distributing it to surrounding pixels in variable proportions according to a diffusion kernel . The result is that input pixel values are perturbed just enough to compensate for the error introduced by previous pixels.
，这一点在WPS下载最新地址中也有详细论述
回顾历史，1960年代，Boswell基金会提供120万美元匹配赠款，撬动居民募捐，建成了第一家医院；1988年，Sun Health基金会捐赠900万美元，建成第二家医院。截至目前，两大基金会累计筹集超过5亿美元，支撑着医院从无到有、从基础到现代化的每一步。，推荐阅读同城约会获取更多信息
Border guards shot dead four people and injured the remaining six aboard the Florida-registered speedboat. Cuba accused the 10 people on the boat of planning "an infiltration with terrorist aims" and said they opened fire first.