python利用生成器随机调整图片对比度，饱和度，亮度，色度

直接上代码

# -*- coding: utf-8 -*-
"""
Created on Thu Apr 23 22:29:54 2020

@author: Administrator
"""
import numpy as np
import cv2
from PIL import Image
from matplotlib import pyplot as plt

#VisualEffect
class VisualEffect:
    """
    生成从给定间隔均匀采用的视觉效果参数
    参数：
    contrast_factor: 对比度因子：调整对比度的因子区间，应该在0-3之间
    brightness_delta: 亮度增量：添加到像素的量在-1和1之间的间隔
    hue_delta:色度增量：为添加到色调通道的量在-1和1之间的间隔
    saturation_factor:饱和系数：因子乘以每个像素的饱和值的区间
    """
    def __init__(
        self,
        contrast_factor,
        brightness_delta,
        hue_delta,
        saturation_factor
        ):
        self.contrast_factor = contrast_factor
        self.brightness_delta = brightness_delta
        self.hue_delta = hue_delta
        self.saturation_factor = saturation_factor
    
    def __call__(self, image):
        """
        将视觉效果应用到图片上
        """
        if self.contrast_factor:
            image = self.adjust_contrast(image, self.contrast_factor)
            
        if self.brightness_delta:
            image = self.adjust_brightness(image, self.brightness_delta)
            
        if self.hue_delta or self.saturation_factor:
            
            image = cv2.cvtColor(image, cv2.COLOR_BGR2HSV) #色彩空间转化
            if self.hue_delta:
                image = self.adjust_hue(image, self.hue_delta)                               
            if self.saturation_factor:
                image = self.adjust_saturation(image, self.saturation_factor)
    
            image = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)#色彩空间转化
            image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
        return image
    
    def adjust_saturation(self, image, factor):
        """
        调整图片的饱和度
        """
        image[..., 1] = np.clip(image[..., 1] * factor, 0, 255)
        return image   
    
    
    
    def adjust_hue(self, image, delta):
        """
        调整图片的色度
        添加到色调通道的量在-1和1之间的间隔。
        如果值超过180，则会旋转这些值。
        """
        image[...,0] = np.mod(image[...,0] + delta * 180, 180) #取余数
        return image    
    def adjust_contrast(self, image, factor):
        """
        调整一张图像的对比度
        """
        mean = image.mean(axis=0).mean(axis=0)
        return self._clip((image - mean) * factor + mean)       
    def adjust_brightness(self,image,delta):
        """
        调整一张图片的亮度
        """
        return self._clip(image + delta * 255)  
    def _clip(self,image):
        """
        剪辑图像并将其转换为np.uint8
        """
        return np.clip(image, 0, 255).astype(np.uint8)
            
def _uniform(val_range):
    """
    随机返回值域之间的数值
    """ 
    return np.random.uniform(val_range[0], val_range[1])                
                
def _check_range(val_range, min_val=None, max_val=None):
    """
    检查间隔是否有效
    """
    if val_range[0] > val_range[1]:
        raise ValueError('interval lower bound > upper bound')
    if min_val is not None and val_range[0] < min_val:
        raise ValueError('invalid interval lower bound')
    if max_val is not None and val_range[1] > max_val:
        raise ValueError('invalid interval upper bound')
#定义随机视觉效果生成器
def random_visual_effect_generator(
        contrast_range=(0.9 ,1.1),
        brightness_range=(-.1, .1),
        hue_range=(-0.05, 0.05),
        saturation_range=(0.95, 1.05)):
        _check_range(contrast_range, 0)
        _check_range(brightness_range, -1, 1)
        _check_range(hue_range, -1, 1)
        _check_range(saturation_range, 0)
        def _generate():
            while True:
                yield VisualEffect(
                contrast_factor=_uniform(contrast_range),
                brightness_delta=_uniform(brightness_range),
                hue_delta=_uniform(hue_range),
                saturation_factor=_uniform(saturation_range)
                )
            
        return _generate()  
if __name__ == "__main__":
    path = "C:/Users/Administrator/Desktop/learning_image/lena.jpg"
    image = np.asarray(Image.open(path))
    
    visual_effect_generator = random_visual_effect_generator(
                contrast_range=(0.9, 1.1),
                brightness_range=(-0.1, 0.1),
                hue_range=(-0.05, 0.05),
                saturation_range=(0.95, 1.05)
            )  #创建生成器
    visual_effect = next(visual_effect_generator)
    image = visual_effect(image)
    
    plt.imshow(image)

以lena图为例
调整之前

调整后