public DifferenceDetector(int x, int y, int width, int height)
{
temp1 = new Image32F(width, height);
temp2 = new Image32F(width, height);
Width = width;
Height = height;
RoiX = x;
RoiY = y;
}
/// <summary>
/// Default constructor initializing the background
/// </summary>
/// <param name="im">Initial background image</param>
protected BackgroundModel(Image8 im)
{
//we allow null to be passed in the constructor to give derived classes the ability
//to initialize the background
if (im == null)
{
return;
}
background = new Image32F(im);
width = im.Width;
height = im.Height;
}
void GenerateMask()
{
//To generate the mask, we use a euclidian distance transform to the center pixel
//followed by a thresholding operation
//To save resources we only do this within the outer square of the circle since
//all pixels outside of that square will be black anyway
double xStart, yStart;
//compute outer square
xStart = _center.x - _radius;
yStart = _center.y - _radius;
if (xStart < 0)
{
xStart = 0;
}
if (yStart < 0)
{
yStart = 0;
}
IppiROI outerSquare = new IppiROI((int)xStart, (int)yStart, 2 * _radius, 2 * _radius);
if (outerSquare.X + outerSquare.Width >= _mask.Width)
{
outerSquare.Width = _mask.Width - outerSquare.X - 1;
}
if (outerSquare.Y + outerSquare.Height >= _mask.Height)
{
outerSquare.Height = _mask.Height - outerSquare.Y - 1;
}
//The distance transform will calculate for all non-0 pixels the distance to the closest
//0 pixel - hence we set all pixels in our mask temporarily to 1 and the circles center to 0
IppHelper.IppCheckCall(ip.ippiSet_8u_C1R(1, _mask.Image, _mask.Stride, _mask.Size));
IppHelper.IppCheckCall(ip.ippiSet_8u_C1R(0, _mask[Center], _mask.Stride, new IppiSize(1, 1)));
//initialize buffers and calculate distance transform within outer square
//we initialize the distance transform image with a value > radius so that all the
//untouched pixel outside of the outer square will later be set to 0
int bufferSize;
IppHelper.IppCheckCall(cv.ippiTrueDistanceTransformGetBufferSize_8u32f_C1R(outerSquare.Size, &bufferSize));
byte * dTransBuffer = (byte *)Marshal.AllocHGlobal(bufferSize);
Image32F distImage = new Image32F(_mask);
IppHelper.IppCheckCall(ip.ippiSet_32f_C1R(Radius + 1, distImage.Image, distImage.Stride, distImage.Size));
IppHelper.IppCheckCall(cv.ippiTrueDistanceTransform_8u32f_C1R(_mask[outerSquare.TopLeft], _mask.Stride, distImage[outerSquare.TopLeft], distImage.Stride, outerSquare.Size, dTransBuffer));
//set all pixels whose value after the distance transform is >radius to 0
IppHelper.IppCheckCall(ip.ippiThreshold_GTVal_32f_C1IR(distImage.Image, distImage.Stride, distImage.Size, Radius, 0));
//now set all pixels whose value is >0 to 1
IppHelper.IppCheckCall(ip.ippiThreshold_GTVal_32f_C1IR(distImage.Image, distImage.Stride, distImage.Size, 0, 1));
//convert dist image, copying it into the mask
IppHelper.IppCheckCall(ip.ippiConvert_32f8u_C1R(distImage.Image, distImage.Stride, _mask.Image, _mask.Stride, _mask.Size, IppRoundMode.ippRndNear));
//Clean up
Marshal.FreeHGlobal((IntPtr)dTransBuffer);
distImage.Dispose();
_maskValid = true;
/*
* //We want to generate the mask with the least amount of pixel-iterations possible
* //based on the radius we can define to rectangular regions for which we can
* //bulk-set the pixels
* //The inner square of the circle is definitely white (centered around center, side-length = sqrt(r*r/2)
* //The outer square is definitely black (centerered around center, side-length=radius)
* double sideLength,xStart,yStart;
*
* //compute inner square
* sideLength = Math.Sqrt(_radius * _radius / 2);
* xStart = _center.x - sideLength / 2;
* yStart = _center.y - sideLength / 2;
* if (xStart < 0)
* xStart = 0;
* if (yStart < 0)
* yStart = 0;
* IppiROI innerSquare = new IppiROI((int)xStart, (int)yStart, (int)sideLength, (int)sideLength);
* if (innerSquare.X + innerSquare.Width >= _mask.Width)
* {
* innerSquare.Width = _mask.Width - innerSquare.X - 1;
* }
* if (innerSquare.Y + innerSquare.Height >= _mask.Height)
* {
* innerSquare.Height = _mask.Height - innerSquare.Y - 1;
* }
*
* //compute outer square
* xStart = _center.x - _radius / 2.0;
* yStart = _center.y - _radius / 2.0;
* if (xStart < 0)
* xStart = 0;
* if (yStart < 0)
* yStart = 0;
* IppiROI outerSquare = new IppiROI((int)xStart, (int)yStart, _radius, _radius);
* if (outerSquare.X + outerSquare.Width >= _mask.Width)
* {
* outerSquare.Width = _mask.Width - outerSquare.X - 1;
* }
* if (outerSquare.Y + outerSquare.Height >= _mask.Height)
* {
* outerSquare.Height = _mask.Height - outerSquare.Y - 1;
* }
*
* //set whole image to black and inner square to 1
* IppHelper.IppCheckCall(ip.ippiSet_8u_C1R(0, _mask.Image, _mask.Stride, _mask.Size));
* IppHelper.IppCheckCall(ip.ippiSet_8u_C1R(1, _mask[innerSquare.TopLeft], _mask.Stride, innerSquare.Size));
*
* //loop over all the pixels that are in between the boundaries of the outer
* //and inner square, measure their distance to the center and
* //p = d>r?0:1;
*/
}
