深度学习之图像的数据增强

　　　在图像的深度学习中，为了丰富图像训练集，更好的提取图像特征，泛化模型（防止模型过拟合），一般都会对数据图像进行数据增强，

数据增强，常用的方式，就是旋转图像，剪切图像，改变图像色差,扭曲图像特征，改变图像尺寸大小，增强图像噪音（一般使用高斯噪音，盐椒噪音）等.

但是需要注意，不要加入其他图像轮廓的噪音.

　　对于常用的图像的数据增强的实现，如下：

# -*- coding:utf-8 -*-
"""数据增强
   1. 翻转变换 flip
   2. 随机修剪 random crop
   3. 色彩抖动 color jittering
   4. 平移变换 shift
   5. 尺度变换 scale
   6. 对比度变换 contrast
   7. 噪声扰动 noise
   8. 旋转变换/反射变换 Rotation/reflection
   author: XiJun.Gong
   date:2016-11-29
"""

from PIL import Image, ImageEnhance, ImageOps, ImageFile
import numpy as np
import random
import threading, os, time
import logging

logger = logging.getLogger(__name__)
ImageFile.LOAD_TRUNCATED_IMAGES = True


class DataAugmentation:
    """
    包含数据增强的八种方式
    """


    def __init__(self):
        pass

    @staticmethod
    def openImage(image):
        return Image.open(image, mode="r")

    @staticmethod
    def randomRotation(image, mode=Image.BICUBIC):
        """
         对图像进行随机任意角度(0~360度)旋转
        :param mode 邻近插值,双线性插值,双三次B样条插值(default)
        :param image PIL的图像image
        :return: 旋转转之后的图像
        """
        random_angle = np.random.randint(1, 360)
        return image.rotate(random_angle, mode)

    @staticmethod
    def randomCrop(image):
        """
        对图像随意剪切,考虑到图像大小范围(68,68),使用一个一个大于(36*36)的窗口进行截图
        :param image: PIL的图像image
        :return: 剪切之后的图像

        """
        image_width = image.size[0]
        image_height = image.size[1]
        crop_win_size = np.random.randint(40, 68)
        random_region = (
            (image_width - crop_win_size) >> 1, (image_height - crop_win_size) >> 1, (image_width + crop_win_size) >> 1,
            (image_height + crop_win_size) >> 1)
        return image.crop(random_region)

    @staticmethod
    def randomColor(image):
        """
        对图像进行颜色抖动
        :param image: PIL的图像image
        :return: 有颜色色差的图像image
        """
        random_factor = np.random.randint(0, 31) / 10.  # 随机因子
        color_image = ImageEnhance.Color(image).enhance(random_factor)  # 调整图像的饱和度
        random_factor = np.random.randint(10, 21) / 10.  # 随机因子
        brightness_image = ImageEnhance.Brightness(color_image).enhance(random_factor)  # 调整图像的亮度
        random_factor = np.random.randint(10, 21) / 10.  # 随机因1子
        contrast_image = ImageEnhance.Contrast(brightness_image).enhance(random_factor)  # 调整图像对比度
        random_factor = np.random.randint(0, 31) / 10.  # 随机因子
        return ImageEnhance.Sharpness(contrast_image).enhance(random_factor)  # 调整图像锐度

    @staticmethod
    def randomGaussian(image, mean=0.2, sigma=0.3):
        """
         对图像进行高斯噪声处理
        :param image:
        :return:
        """

        def gaussianNoisy(im, mean=0.2, sigma=0.3):
            """
            对图像做高斯噪音处理
            :param im: 单通道图像
            :param mean: 偏移量
            :param sigma: 标准差
            :return:
            """
            for _i in range(len(im)):
                im[_i] += random.gauss(mean, sigma)
            return im

        # 将图像转化成数组
        img = np.asarray(image)
        img.flags.writeable = True  # 将数组改为读写模式
        width, height = img.shape[:2]
        img_r = gaussianNoisy(img[:, :, 0].flatten(), mean, sigma)
        img_g = gaussianNoisy(img[:, :, 1].flatten(), mean, sigma)
        img_b = gaussianNoisy(img[:, :, 2].flatten(), mean, sigma)
        img[:, :, 0] = img_r.reshape([width, height])
        img[:, :, 1] = img_g.reshape([width, height])
        img[:, :, 2] = img_b.reshape([width, height])
        return Image.fromarray(np.uint8(img))

    @staticmethod
    def saveImage(image, path):
        image.save(path)


def makeDir(path):
    try:
        if not os.path.exists(path):
            if not os.path.isfile(path):
                # os.mkdir(path)
                os.makedirs(path)
            return 0
        else:
            return 1
    except Exception, e:
        print str(e)
        return -2


def imageOps(func_name, image, des_path, file_name, times=5):
    funcMap = {"randomRotation": DataAugmentation.randomRotation,
               "randomCrop": DataAugmentation.randomCrop,
               "randomColor": DataAugmentation.randomColor,
               "randomGaussian": DataAugmentation.randomGaussian
               }
    if funcMap.get(func_name) is None:
        logger.error("%s is not exist", func_name)
        return -1

    for _i in range(0, times, 1):
        new_image = funcMap[func_name](image)
        DataAugmentation.saveImage(new_image, os.path.join(des_path, func_name + str(_i) + file_name))


opsList = {"randomRotation", "randomCrop", "randomColor", "randomGaussian"}


def threadOPS(path, new_path):
    """
    多线程处理事务
    :param src_path: 资源文件
    :param des_path: 目的地文件
    :return:
    """
    if os.path.isdir(path):
        img_names = os.listdir(path)
    else:
        img_names = [path]
    for img_name in img_names:
        print img_name
        tmp_img_name = os.path.join(path, img_name)
        if os.path.isdir(tmp_img_name):
            if makeDir(os.path.join(new_path, img_name)) != -1:
                threadOPS(tmp_img_name, os.path.join(new_path, img_name))
            else:
                print 'create new dir failure'
                return -1
                # os.removedirs(tmp_img_name)
        elif tmp_img_name.split('.')[1] != "DS_Store":
            # 读取文件并进行操作
            image = DataAugmentation.openImage(tmp_img_name)
            threadImage = [0] * 5
            _index = 0
            for ops_name in opsList:
                threadImage[_index] = threading.Thread(target=imageOps,
                                                       args=(ops_name, image, new_path, img_name,))
                threadImage[_index].start()
                _index += 1
                time.sleep(0.2)


if __name__ == '__main__':
    threadOPS("/home/pic-image/train/12306train",
              "/home/pic-image/train/12306train3")