python opencv图像对比度_Python OpenCV cv2使图像亮度和对比度提高100%的简单方法

这里有一个非常数学和直接的方法来调整亮度和对比度作为参数。对比度控制输出值与输入值绘图中直线方程的斜率。截距取决于亮度和对比度。亮度控制直线坡度的轴点，以便所需结果越亮，轴点越高。这里的代码提供了bri和con参数，这些参数可以在-100到100范围内更改，但是限制了这样就不能反转对比度。值bri=0和con=-100将使图像饱和度降低，使其完全处于中灰色。值bri=100和con=-100将生成纯白色图像。同样，bri=-100和con=-100将生成纯黑色图像。所以bri和con的值就像百分比变化。因此，bri=0和con=0与输入没有变化。在

输入：

import cv2

import numpy as np

import math

# load image with alpha channel

img = cv2.imread('lena.png')

# define desired brightness and contrast change values

bri = 20

con = 20

# compute slope and intercept

diffcon = (100 - con)

if diffcon <= 0.1: con=99.9

arg = math.pi * (((con * con) / 20000) + (3 * con / 200)) / 4

slope = 1 + (math.sin(arg) / math.cos(arg))

if slope < 0: slope=0

pivot = (100 - bri) / 200

intcpbri = bri / 100

intcpcon = pivot * (1 - slope)

intercept = (intcpbri + intcpcon)

# print slope and intercept

print(slope, intercept)

# apply slope and intercept

img = img/255.0

out = slope * img + intercept

out[out>1] = 1

out[out<0] = 0

# display IN and OUT images

cv2.imshow('IN', img)

cv2.imshow('OUT', out)

cv2.waitKey(0)

cv2.destroyAllWindows()

# save output image

out = 255.0 * out

out = out.astype(int)

cv2.imwrite('lena_bc_20_20.png', out)