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Editorial Team
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Asked: 2026-05-29T06:07:15+00:00

I am trying to acquire single images from a camera, do some processing to

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I am trying to acquire single images from a camera, do some processing to them and release the used memory. I’ve been doing it for quite some time with a code similar to the one that follows:

char* img_data = new char[ len ]; // I retrieve len from the camera.

// Grab the actual image from the camera: 
// It fills the previous buffer with the image data.
// It gives width and height.

CvSize size;
size.width = width;
size.height = height;
IplImage* img = cvCreateImageHeader( size, 8, 1 );
img->imageData = img_data;

// Do the processing

cvReleaseImage( &img );

This code runs fine. I have recently read here (in the imageData description) that I shouldn’t be assigning data directly to img->imageData but use SetData() instead, like so:

cvSetData( img, img_data, width );

However, when I do it like this, I get a Segmentation fault at the cvReleaseImage() call.

What am I doing wrong?

Thank you.

EDIT: I have tried to compile and run the program that @karlphillip suggested and I DO get a segmentation fault using cvSetData but it runs fine when assigning the data directly.
I’m using Debian 6 and OpenCV 2.3.1.

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1 Answer

  1. Editorial Team

    I had this problem as well, but believe it was fixed from what I gathered in
    this comment; namely to use cvReleaseImageHeader() and not cvReleaseImage().

    For example:

    unsigned int width = 100;
unsigned int height = 100;
unsigned int channels = 1;
unsigned char* imageData = (unsigned char*)malloc(width*height*channels);
// set up the image data

IplImage *img = cvCreateImageHeader(cvSize(width, height), IPL_DEPTH_8U, channels);
cvSetData(img, imageData, width*channels); 

// use img

cvReleaseImageHeader(&img);

// free(imageData) when finished
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