Python OpenCV 将图像转换为字节字符串？
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Python OpenCV convert image to byte string?
提问by xercool
I'm working with PyOpenCV. How to convert cv2 image (numpy) to binary string for writing to MySQL db without a temporary file and imwrite?
我正在使用 PyOpenCV。如何将 cv2 图像（numpy）转换为二进制字符串，以便在没有临时文件的情况下写入 MySQL 数据库和imwrite？
I googled it but found nothing...
我用谷歌搜索，但什么也没找到……
I'm trying imencode, but it doesn't work.
我正在尝试imencode，但它不起作用。
capture = cv2.VideoCapture(url.path)
capture.set(cv2.cv.CV_CAP_PROP_POS_MSEC, float(url.query))
self.wfile.write(cv2.imencode('png', capture.read()))
Error:
错误：
File "server.py", line 16, in do_GET
self.wfile.write(cv2.imencode('png', capture.read()))
TypeError: img is not a numerical tuple
Help somebody!
帮助某人！
回答by berak
capture.read() returns a tuple, (err,img).
capture.read() 返回一个元组，(err,img)。
try splitting it up:
尝试拆分它：
_,img = capture.read()
self.wfile.write(cv2.imencode('png', img))
回答by themadmax
My code to use opencv with python cgi :
我在 python cgi 中使用 opencv 的代码：
im_data = form['image'].file.read()
im = cv2.imdecode( np.asarray(bytearray(im_data), dtype=np.uint8), 1 )
ret, im_thresh = cv2.threshold( im, 128, 255, cv2.THRESH_BINARY )
self.send_response(200)
self.send_header("Content-type", "image/jpg")
self.end_headers()
ret, buf = cv2.imencode( '.jpg', im_thresh )
self.wfile.write( np.array(buf).tostring() )
回答by jabaldonedo
If you have an image img(which is a numpy array) you can convert it into string using:
如果您有一个图像img（这是一个 numpy 数组），您可以使用以下方法将其转换为字符串：
>>> img_str = cv2.imencode('.jpg', img)[1].tostring()
>>> type(img_str)
'str'
Now you can easily store the image inside your database, and then recover it by using:
现在您可以轻松地将图像存储在数据库中，然后使用以下命令恢复它：
>>> nparr = np.fromstring(STRING_FROM_DATABASE, np.uint8)
>>> img = cv2.imdecode(nparr, cv2.CV_LOAD_IMAGE_COLOR)
where you need to replace STRING_FROM_DATABASEwith the variable that contains the result of your query to the database containing the image.
您需要将STRING_FROM_DATABASE包含查询结果的变量替换为包含图像的数据库。
回答by remort
im = cv2.imread('/tmp/sourcepic.jpeg')
res, im_png = cv2.imencode('.png', im)
with open('/tmp/pic.png', 'wb') as f:
f.write(im_png.tobytes())
回答by CKboss
Here is an example:
下面是一个例子：
def image_to_bts(frame):
'''
:param frame: WxHx3 ndarray
'''
_, bts = cv2.imencode('.webp', frame)
bts = bts.tostring()
return bts
def bts_to_img(bts):
'''
:param bts: results from image_to_bts
'''
buff = np.fromstring(bts, np.uint8)
buff = buff.reshape(1, -1)
img = cv2.imdecode(buff, cv2.IMREAD_COLOR)
return img
