正在做一个把matlab程序转python的工作,遇到 matlab里面的 imadjust 函数,但是找了一圈没有对应的python函数,需要自定义一个函数
import numpy as np
from bisect import bisect_left
# 已测试完毕,成功
def imadjust(src, tol=1, vin=[0, 255], vout=(0, 255)):
# src : input one-layer image (numpy array)
# tol : tolerance, from 0 to 100.
# vin : src image bounds
# vout : dst image bounds
# return : output img
assert len(src.shape) == 2, 'Input image should be 2-dims'
tol = max(0, min(100, tol))
if tol > 0:
# Compute in and out limits
# Histogram
hist = np.histogram(src, bins=list(range(256)), range=(0, 255))[0]
# Cumulative histogram
cum = hist.copy()
for i in range(1, 255): cum[i] = cum[i - 1] + hist[i]
# Compute bounds
total = src.shape[0] * src.shape[1]
low_bound = total * tol / 100
upp_bound = total * (100 - tol) / 100
vin[0] = bisect_left(cum, low_bound)
vin[1] = bisect_left(cum, upp_bound)
# Stretching
scale = (vout[1] - vout[0]) / (vin[1] - vin[0])
vs = src - vin[0]
vs[src < vin[0]] = 0
vd = vs * scale + 0.5 + vout[0]
vd[vd > vout[1]] = vout[1]
dst = vd
return dst
src是一个二维矩阵,数据类型为uint8(0-255,用来表示灰度值),测试结果和matlab基本一模一样。做到了同输入同输出。
用到了 bisect_left 它的用法可以参考 python:从整数列表(数组)中获取最接近给定值的数字
当然,最好看文档 bisect — 数组二分查找算法,讲的比较好