python OpenCV jpeg compression in memory

Question

In OpenCV it is possible to save an image to disk with a certain jpeg compression. Is there also a way to do this in memory? Or should I write a function using cv2.imsave() that loads the file and removes it again from disk? If anyone knows a better way that is also fine.

The use case is real-time data augmentation. Using something else than OpenCV would cause possibly unnecessary overhead.

Example of desired function im = cv2.imjpgcompress(90)

Miki · Accepted Answer · 2018-11-07 10:26:55Z

71

You can use imencode:

encode_param = [int(cv2.IMWRITE_JPEG_QUALITY), 90]
result, encimg = cv2.imencode('.jpg', img, encode_param)

(The default value for IMWRITE_JPEG_QUALITY is 95.)

You can decode it back with:

decimg = cv2.imdecode(encimg, 1)

_{Snippet from here}

edited Nov 7, 2018 at 10:26

answered Nov 23, 2016 at 15:46

Miki

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2 Comments

Simon Over a year ago

The shape of the encimg is different from that of im. Why is that? Before: 340 1080 3 After: 58154 1

Simon Over a year ago

import cv2 filename = 'image.png' im = cv2.imread(filename) encode_param = [int(cv2.IMWRITE_JPEG_QUALITY), 80] result, im = cv2.imencode('.jpg', im, encode_param) print result

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