Python base64 encodes and decodes images into the formats required by numpy, opencv, and matplot

This blog will introduce how Python encodes and decodes images to base64 and reads them into the formats required by numpy, opencv, and matplot.

1. Rendering

The original image is as follows:

The rendering of base64 converted to numpy array is as follows (one-dimensional):
insert image description here

The base64 conversion to opencv BGR VS grayscale rendering is as follows:

insert image description here
The base64 conversion to matplot RGB VS grayscale rendering is as follows:

insert image description here

2. Source code

base64 encoded image as string
base64 decode string to image
base64 decode string into numpy, opencv, matplot images

# 对图片进行base64编码，解码，解码为numpy，opencv，matplot照片
# USAGE
# python base64_2_jpg.py

import base64

import cv2
import numpy as np
from matplotlib import pyplot as plt


# 将字符串写入文字
#  name 图片名
#  base64_data 图片二进制编码后string流
def write2txt(name, base64_data):
    # 写入_base64.txt
    print(name)
    print(name,len(base64_data))
    basef = open(name + '_base64.txt', 'w')
    data = 'data:image/jpg;base64,%s' % base64_data
    # print(data)
    basef.write(base64_data)
    basef.close()


# 编码图像为base64字符串
def encode_base64(file):
    with open(file, 'rb') as f:
        img_data = f.read()
        base64_data = base64.b64encode(img_data)
        print(type(base64_data))
        # print(base64_data)
        # 如果想要在浏览器上访问base64格式图片，需要在前面加上：data:image/jpeg;base64,
        base64_str = str(base64_data, 'utf-8')
        # print(base64_str)
        print(len(base64_data))
        write2txt(file.replace(".jpg", ""), base64_str)
        return base64_data


# 解码base64字符串为图像，并保存
def decode_base64(base64_data):
    with open('./images/base64.jpg', 'wb') as file:
        img = base64.b64decode(base64_data)
        file.write(img)


# 解码base64字符串为numpy图像、opencv、matplot图像

# 解码base64字符串为numpy图像
def decode_base64_np_img(base64_data):
    img = base64.b64decode(base64_data)
    img_array = np.fromstring(img, np.uint8)  # 转换np序列
    print('numpy: ', img_array.shape)
    cv2.imshow("img", img_array)
    cv2.waitKey(0)


# 解码base64字符串为opencv图像
def decode_base64_cv_img(base64_data):
    img = base64.b64decode(base64_data)
    img_array = np.fromstring(img, np.uint8)  # 转换np序列
    img_raw = cv2.imdecode(img_array, cv2.IMREAD_COLOR)  # 转换Opencv格式BGR
    img_gray = cv2.imdecode(img_array, cv2.IMREAD_GRAYSCALE)  # 转换灰度图

    print('opencv bgr: ', img_raw.shape)
    print('opencv gray: ', img_gray.shape)

    cv2.imshow("img bgr", img_raw)
    cv2.imshow("img gray", img_gray)
    cv2.waitKey(0)


# 解码base64字符串为matplot图像
def decode_base64_matplot_img(base64_data):
    img = base64.b64decode(base64_data)
    img_array = np.fromstring(img, np.uint8)  # 转换np序列
    img_raw = cv2.imdecode(img_array, cv2.IMREAD_COLOR)  # 转换Opencv格式BGR
    img_matplot = cv2.cvtColor(img_raw, cv2.COLOR_BGR2RGB)  # BGR转RGB

    img_gray = cv2.imdecode(img_array, cv2.IMREAD_GRAYSCALE)  # 转换灰度图
    imggray_matplot = cv2.cvtColor(img_gray, cv2.COLOR_GRAY2RGB)  # 灰度图转RGB
    plt.figure()
    plt.title("Matplot RGB Origin Image")
    plt.axis("off")
    plt.imshow(img_matplot)

    plt.figure()
    plt.title("Matplot Gray Origin Image")
    plt.axis("off")
    plt.imshow(imggray_matplot)
    plt.show()


if __name__ == '__main__':
    img_path = './images/1622175322109_0.025711.jpg'
    base64_data = encode_base64(img_path)
    decode_base64(base64_data)

    decode_base64_np_img(base64_data)
    decode_base64_cv_img(base64_data)
    decode_base64_matplot_img(base64_data)