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imageData function in OpenCV with Python

Answer 1

A:

If you're sure that the data you're getting as a string is actually an integer, you can cast it to an int.

i.e.

data = int(img.imageData)

http://docs.python.org/library/functions.html#int

This probably isn't the right way to achieve your goals however. Have you looked at the built-in library function examples?

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

Paul McMillan 2010-10-04 23:33:04

I doubt `int(imageData)` is what you're looking for, as `imageData` will be a binary string…

David Wolever 2010-10-04 23:38:34

Good call on the array operations, though — they are very helpful.

David Wolever 2010-10-04 23:39:02

Answer 2

+1 A:

As you've said, the imageData property returns a binary string containing the "raw image data" (I don't recall what format, though). Instead, you should access the image data by indexing into the img object:

>>> img = cv.CreateImage((10, 10), 8, 1)
>>> img[0, 0]
0.0
>>> img[0, 3] = 1.3
>>>

David Wolever 2010-10-04 23:34:10

Oh, dang, sorry — didn't notice that you're using version 1 of the Python bindings, so my answer may not apply (I only know version 2).

David Wolever 2010-10-04 23:38:07

An example of my imageData => "\x1e\x1e)))***///111666@@@IIIWWW]]]<<<:::TTT^^^}}}jjjQQQDDD<<<SSSYYYQQQNNN;;;MMMqqq\x7f\x7f\x7f\x8d\x8d\x8dhhhWWWRRRQQQPPPUUUgggvvv\x8c\x8c\x8c\x84"

Resul 2010-10-04 23:44:45

The problem is, I am implementing a function by looking at a C code, and as I said they were able to do the transformation by using the ImageData. But I don't understand how they can do it. Is there a way to convert binary string to a integer in Python? Maybe in C language the chars (i don't have experiencve in C) it automatically converted to integer..

Resul 2010-10-04 23:47:24

To turn that "string" into an "integer" you'd use something like this: `data = [ord(ch) for ch in imageData]` — then you could do stuff like `data[3] = data[6] + data[8]`. However, the conversion would be (comparatively) slow, so if I were you I'd look into the methods available on `img` to see if there's something like `getPixel`. You can list all the properties on `img` (methods and fields) using `dir(img)`.

David Wolever 2010-10-05 16:55:39

Of course, if it's possible to update your OpenCV bindings and use version 2, then you can use the syntax I've shown in my answer (and a bunch of other happy things)… But I realize that may not be possible.

David Wolever 2010-10-05 17:00:12

Answer 3

A:

Try this:

http://stackoverflow.com/questions/3528813/capture-image-as-array-with-python-opencv/3533462#3533462

I encourage you to take a look at Python OpenCV Cookbook.

karlphillip 2010-10-05 21:49:41

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