/// <summary>
/// Extract blobs from an image in which distinct contiguous regions are marked
/// with distinct pixel values such as returned by ippiLabelMarkers
/// </summary>
/// <param name="imMarkers">The marker image</param>
/// <param name="nMarkers">The number of expected markers</param>
/// <param name="imOriginal">The original image. Used for pixel-intensity information</param>
/// <param name="roi">The roi in which to perform blob extraction</param>
/// <returns>An array of discovered blobs</returns>
public static BlobWithMoments[] ExtractBlobs(Image8 imMarkers, int nMarkers, IppiROI roi)
{
if (nMarkers == 0)//no point to iterate over the image if no marker was found
{
return(null);
}
BlobWithMoments[] blobs = new BlobWithMoments[nMarkers];
byte markerValue;
//loop over ROI in marker image, adding pixels to their appropriate blob
for (int i = roi.Y; i < roi.Y + roi.Height; i++)
{
for (int j = roi.X; j < roi.X + roi.Width; j++)
{
markerValue = imMarkers.Image[i * imMarkers.Stride + j];
if (markerValue != 0) //it belongs to a blob!
{
//since the lowest marker has the value 1 we need to deduct 1 from markerValue for 0-index based array mapping!
if (blobs[markerValue - 1] == null)
{
blobs[markerValue - 1] = new BlobWithMoments();
}
blobs[markerValue - 1].AddPixel(j, i);
}
}
}
return(blobs);
}
/// <summary>
/// Performs an opening operation in the specified ROI using the specified
/// neighborhood mask
/// </summary>
/// <param name="imIn">The image to perform the opening operation on</param>
/// <param name="imOpened">The image after the opening operation</param>
/// <param name="imCalc">Intermediate buffer for processing</param>
/// <param name="neighborhood">The mask for the opening operation</param>
/// <param name="region">The image region in which to perform the operation</param>
public static void Open(Image8 imIn, Image8 imOpened, Image8 imCalc, MorphologyMask neighborhood, IppiROI roi)
{
//Modify region we operate on to allow mask overhang
var inner = new IppiROI(roi.X + neighborhood.Anchor.x, roi.Y + neighborhood.Anchor.y, roi.Width - neighborhood.Mask.Width, roi.Height - neighborhood.Mask.Height);
IppHelper.IppCheckCall(ip.ippiErode_8u_C1R(imIn[inner.TopLeft], imIn.Stride, imCalc[inner.TopLeft], imCalc.Stride, inner.Size, neighborhood.Mask.Image, neighborhood.Mask.Size, neighborhood.Anchor));
IppHelper.IppCheckCall(ip.ippiDilate_8u_C1R(imCalc[inner.TopLeft], imCalc.Stride, imOpened[inner.TopLeft], imOpened.Stride, inner.Size, neighborhood.Mask.Image, neighborhood.Mask.Size, neighborhood.Anchor));
}
/// <summary>
/// Performs a 3x3 opening operation on an image - removes speckles
/// </summary>
/// <param name="imIn">The image to perform an opening operation on</param>
/// <param name="imOpened">The image after the opening operation</param>
/// <param name="imCalc">Intermediate image for semi-processed version</param>
/// <param name="region">The ROI in which to perform the operation</param>
public static void Open3x3(Image8 imIn, Image8 imOpened, Image8 imCalc, IppiROI roi)
{
//Modify region we operate on to allow mask overhang
var inner = new IppiROI(roi.X + 1, roi.Y + 1, roi.Width - 3, roi.Height - 3);
IppHelper.IppCheckCall(ip.ippiErode3x3_8u_C1R(imIn[inner.TopLeft], imIn.Stride, imCalc[inner.TopLeft], imCalc.Stride, inner.Size));
IppHelper.IppCheckCall(ip.ippiDilate3x3_8u_C1R(imCalc[inner.TopLeft], imCalc.Stride, imOpened[inner.TopLeft], imOpened.Stride, inner.Size));
}
public virtual void UpdateBackground(Image8 im, BlobWithMoments regionToExclude)
{
if (regionToExclude == null)
{
UpdateBackground(im);
}
else
{
//reset our mask to <update all>, then fill bounding box with 0s
ip.ippiSet_8u_C1R(byte.MaxValue, _updateMask.Image, _updateMask.Stride, _updateMask.Size);
IppiROI roi = new IppiROI(regionToExclude.BoundingBox.x, regionToExclude.BoundingBox.y, regionToExclude.BoundingBox.width, regionToExclude.BoundingBox.height);
ip.ippiSet_8u_C1R(0, _updateMask[regionToExclude.BB_TopLeft], _updateMask.Stride, regionToExclude.BB_Size);
IppHelper.IppCheckCall(cv.ippiAddWeighted_8u32f_C1IMR(im.Image, im.Stride, _updateMask.Image, _updateMask.Stride, background.Image, background.Stride, im.Size, FractionUpdate));
}
}
public virtual void UpdateBackground(Image8 im, Blob[] regionsToExclude)
{
if (regionsToExclude == null)//do a simple update
{
UpdateBackground(im);
}
else
{
//reset our mask to <update all>, then fill all bounding boxes with 0s
ip.ippiSet_8u_C1R(byte.MaxValue, _updateMask.Image, _updateMask.Stride, _updateMask.Size);
foreach (Blob b in regionsToExclude)
{
if (b != null)
{
IppiROI roi = new IppiROI(b.BoundingBox);
ip.ippiSet_8u_C1R(0, _updateMask[roi.TopLeft], _updateMask.Stride, roi.Size);
}
}
IppHelper.IppCheckCall(cv.ippiAddWeighted_8u32f_C1IMR(im.Image, im.Stride, _updateMask.Image, _updateMask.Stride, background.Image, background.Stride, im.Size, FractionUpdate));
}
}
/// <summary>
/// Implements a "greater than" threshold like MATLABS
/// im2bw function
/// </summary>
/// <param name="imIn">The image to threshold</param>
/// <param name="imThresh">The image after thresholding</param>
/// <param name="region">The ROI in which to perform the operation</param>
/// <param name="threshold">The threshold to apply</param>
public static void Im2Bw(Image8 imIn, Image8 imThresh, IppiROI region, byte threshold)
{
IppHelper.IppCheckCall(ip.ippiThreshold_LTVal_8u_C1R(imIn[region.TopLeft], imIn.Stride, imThresh[region.TopLeft], imThresh.Stride, region.Size, (byte)(threshold + 1), 0));
IppHelper.IppCheckCall(ip.ippiThreshold_GTVal_8u_C1IR(imThresh[region.TopLeft], imThresh.Stride, region.Size, threshold, 255));
}
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;
*/
}