28Feb/092
Draw IplImage
OpenCV stores images in a data structure called IplImage. They provide methods for rendering it to the screen, but if you want to use OpenGL instead (which should be faster and gives you more flexibility), I wrote the following code. It should be a little faster than loading the IplImage into a texture first, and then drawing it (if you have to do this every frame).
void DrawIplImage(IplImage *image, int x = 0, int y = 0, GLfloat xZoom = 1.0f, GLfloat yZoom = 1.0f)
{
GLenum format;
switch(image->nChannels) {
case 1:
format = GL_LUMINANCE;
break;
case 2:
format = GL_LUMINANCE_ALPHA;
break;
case 3:
format = GL_BGR;
break;
default:
return;
}
glRasterPos2i(x, y);
glPixelZoom(xZoom, yZoom);
glDrawPixels(image->width, image->height, format, GL_UNSIGNED_BYTE, image->imageData);
}
{
GLenum format;
switch(image->nChannels) {
case 1:
format = GL_LUMINANCE;
break;
case 2:
format = GL_LUMINANCE_ALPHA;
break;
case 3:
format = GL_BGR;
break;
default:
return;
}
glRasterPos2i(x, y);
glPixelZoom(xZoom, yZoom);
glDrawPixels(image->width, image->height, format, GL_UNSIGNED_BYTE, image->imageData);
}
It should be pretty straight forward to use. Handles IplImages with 1 or 3 layers. Should work with 2 layers too, but I haven't needed or found an example of this.
April 19th, 2012 - 16:02
This works great.. only problem is the webcam image is flipped vertically.
April 19th, 2012 - 16:06
Fixed it.. since gl draws from the bottom up x=0, y=0, xZoom = 1.0, yZoom = -1.0