Question

As stated in documentation:

IplImage.imageData (from OpenCV library):

A pointer to the aligned image data

Image.tostring() (from Python PIL):

Returns a string containing pixel data, using the standard “raw”
encoder.

What is the difference between the results of Image.tostring() and IplImage.imageData ? What should I do if I want to get exactly the same data as returned by IplImage.imageData in Python ?

EDIT:
Just to clarify, I need to use PIL to load images as I have a python service to receive data from internet and there’s no straightforward way in OpenCV to load an image from memory instead of disk.

Answer 1

While Opencv image, pixel data is ordered as BGR, in PIL it is RGB.
You can convert a PIL image data to opencv as below.

import Image, cv
pi = Image.open('building.jpg')       # PIL image
cv_im = cv.CreateImageHeader(pi.size, cv.IPL_DEPTH_8U, 3)
cv.SetData(cv_im, pi.tostring())

For more information here.

http://opencv.willowgarage.com/documentation/python/cookbook.html