The local maximum and minimum in reflectance spectral curve, corresponding to reflectance apex and Absorption apex, can be used to retrieval also, but effective matching strategy should be adopted.

基于光谱特征的检索可以通过提取反射和吸收光谱、光谱特征匹配的方法进行；

youdao

First, nonlinear stack filter is applied to estimate the maximum and minimum of noise-free image's gray scale value in a local region.

首先非线性堆滤波器用于求出图象某象素点邻域内的灰度最大值与最小值的最优估计，然后以此两估计值之差代替原象素点灰度值。

youdao

With the features of a function's derivatives at a point, this paper discussed some problems of the function, such as monotonicity, local maximum, local minimum, inflection point, and asymptote.

本文利用函数某处的各阶导数的特点，以确定函数在该处的单调、极大值、极小值、拐点及浙近线等。

youdao