Python OpenCV从字节字符串加载图像 [英] Python OpenCV load image from byte string

问题描述

我正在尝试从字符串加载图像，如PHP函数 imagecreatefromstring

I'm trying to load image from string like as PHP function imagecreatefromstring

我该怎么做？

我有MySQL blob字段图像。我正在使用 MySQLdb ，并且不希望创建临时文件来处理PyOpenCV中的图像。

I have MySQL blob field image. I'm using MySQLdb and don't want create temporary file for working with images in PyOpenCV.

注意：需要cv（不是cv2）包装函数

NOTE: need cv (not cv2) wrapper function

推荐答案

这就是我通常用来将存储在数据库中的图像转换为Python中的OpenCV图像。

This is what I normally use to convert images stored in database to OpenCV images in Python.

import numpy as np
import cv2
from cv2 import cv

# Load image as string from file/database
fd = open('foo.jpg')
img_str = fd.read()
fd.close()

# CV2
nparr = np.fromstring(img_str, np.uint8)
img_np = cv2.imdecode(nparr, cv2.CV_LOAD_IMAGE_COLOR) # cv2.IMREAD_COLOR in OpenCV 3.1

# CV
img_ipl = cv.CreateImageHeader((img_np.shape[1], img_np.shape[0]), cv.IPL_DEPTH_8U, 3)
cv.SetData(img_ipl, img_np.tostring(), img_np.dtype.itemsize * 3 * img_np.shape[1])

# check types
print type(img_str)
print type(img_np)
print type(img_ipl)

我已经从 numpy.ndarray 到 cv2.cv.iplimage ，因此上面的脚本将打印出来：

I have added the conversion from numpy.ndarray to cv2.cv.iplimage, so the script above will print:

<type 'str'>
<type 'numpy.ndarray'>
<type 'cv2.cv.iplimage'>

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