/// <summary>
/// returns the length of the longest path from this blob feature
/// </summary>
/// <param name="mark_path">mark the longest path as being selected</param>
/// <param name="best_end_point">blob at the longest distance</param>
/// <returns></returns>
public int getLongestPath(bool mark_path, ref blob end_point)
{
int longest = 0;
float best_ang = 0;
float tollerance_degrees = 5;
for (int i = 0; i < neighbours.Count; i++)
{
float ang = (float)angle[i];
blob curr_end_point = null;
int length = getDirectionalLength(ang, false, true, 0, 1000, tollerance_degrees, ref curr_end_point);
if (length > longest)
{
longest = length;
best_ang = ang;
end_point = curr_end_point;
}
}
if ((longest > 0) && (mark_path))
{
blob curr_end_point = null;
getDirectionalLength(best_ang, true, true, 0, 1000, tollerance_degrees, ref curr_end_point);
}
return(longest);
}
/// <summary>
/// returns the distance from this blob to another
/// </summary>
/// <param name="other">the other blob object</param>
/// <returns>distance to the other blob</returns>
public float getSeparation(blob other)
{
float dx = other.interpolated_x - interpolated_x;
float dy = other.interpolated_y - interpolated_y;
float dist = (float)Math.Sqrt((dx * dx) + (dy * dy));
return(dist);
}
/// <summary>
/// returns a copy of this blob
/// </summary>
public blob Copy()
{
blob new_blob = new blob(x, y);
new_blob.interpolated_x = interpolated_x;
new_blob.interpolated_y = interpolated_y;
new_blob.average_radius = average_radius;
new_blob.ovality = ovality;
new_blob.average_intensity = average_intensity;
return (new_blob);
}
/// <summary>
/// returns a copy of this blob
/// </summary>
public blob Copy()
{
blob new_blob = new blob(x, y);
new_blob.interpolated_x = interpolated_x;
new_blob.interpolated_y = interpolated_y;
new_blob.average_radius = average_radius;
new_blob.ovality = ovality;
new_blob.average_intensity = average_intensity;
return(new_blob);
}
/// <summary>
/// add a neighbour if it's in da hood
/// </summary>
/// <param name="neighbour">a possibly neighbouring blob</param>
/// <param name="neighbourhood_radius">the neighbourhood event horizon</param>
public bool AddNeighbour(blob neighbour, float neighbourhood_radius)
{
float dx = neighbour.interpolated_x - interpolated_x;
float dy = neighbour.interpolated_y - interpolated_y;
float dist = (float)Math.Sqrt((dx * dx) + (dy * dy));
if (dist < neighbourhood_radius)
{
AddNeighbour(neighbour);
return(true);
}
else
{
return(false);
}
}
/// <summary>
/// everybody needs good neighbours...
/// </summary>
/// <param name="neighbour">a neighbouring blob</param>
public void AddNeighbour(blob neighbour)
{
// update the neighbours list
neighbours.Add(neighbour);
// calculate the separation
float dist = getSeparation(neighbour);
separation.Add(dist);
// calculate the angle to this neighbour
float ang = 0;
if (dist > 0.1f)
{
float dx = neighbour.interpolated_x - interpolated_x;
float dy = neighbour.interpolated_y - interpolated_y;
ang = (float)Math.Asin(dx / dist);
if (dy < 0)
{
ang = (float)(Math.PI * 2) - ang;
}
if (ang < 0)
{
ang += (float)(Math.PI);
}
if (ang == float.NaN)
{
ang = 0;
}
}
angle.Add(ang);
// populate the direction lookup table
int ang_index = (int)Math.Round((ang * 180 / Math.PI) / direction_increment_degrees);
if (ang_index >= neighbourDirections.Length)
{
ang_index = neighbourDirections.Length - 1;
}
if (neighbourDirections[ang_index] == null)
{
neighbourDirections[ang_index] = new ArrayList();
}
neighbourDirections[ang_index].Add(neighbours.Count - 1);
}
/// <summary>
/// add a neighbour if it's in da hood
/// </summary>
/// <param name="neighbour">a possibly neighbouring blob</param>
/// <param name="neighbourhood_radius">the neighbourhood event horizon</param>
public bool AddNeighbour(blob neighbour, float neighbourhood_radius)
{
float dx = neighbour.interpolated_x - interpolated_x;
float dy = neighbour.interpolated_y - interpolated_y;
float dist = (float)Math.Sqrt((dx * dx) + (dy * dy));
if (dist < neighbourhood_radius)
{
AddNeighbour(neighbour);
return (true);
}
else return (false);
}
/// <summary>
/// returns the distance from this blob to another
/// </summary>
/// <param name="other">the other blob object</param>
/// <returns>distance to the other blob</returns>
public float getSeparation(blob other)
{
float dx = other.interpolated_x - interpolated_x;
float dy = other.interpolated_y - interpolated_y;
float dist = (float)Math.Sqrt((dx * dx) + (dy * dy));
return (dist);
}
/// <summary>
/// returns the length of the longest path from this blob feature
/// </summary>
/// <param name="mark_path">mark the longest path as being selected</param>
/// <param name="best_end_point">blob at the longest distance</param>
/// <returns></returns>
public int getLongestPath(bool mark_path, ref blob end_point)
{
int longest = 0;
float best_ang = 0;
float tollerance_degrees = 5;
for (int i = 0; i < neighbours.Count; i++)
{
float ang = (float)angle[i];
blob curr_end_point = null;
int length = getDirectionalLength(ang, false, true,0,1000, tollerance_degrees, ref curr_end_point);
if (length > longest)
{
longest = length;
best_ang = ang;
end_point = curr_end_point;
}
}
if ((longest > 0) && (mark_path))
{
blob curr_end_point = null;
getDirectionalLength(best_ang, true, true,0,1000, tollerance_degrees, ref curr_end_point);
}
return (longest);
}
public int getDirectionalLength(float direction_radians,
bool mark_path,
bool ignore_selected,
int depth, int max_depth,
float tollerance_degrees,
ref blob end_point)
{
int length = 0;
// mark the path if necessary
if (mark_path) selected = true;
if (depth < max_depth)
{
// get the index of the lookup table for this direction
int ang_index = (int)Math.Round((direction_radians * 180 / Math.PI) / direction_increment_degrees);
if (ang_index >= neighbourDirections.Length)
ang_index -= neighbourDirections.Length;
// search for neighbours in this direction
float max_ang_diff = tollerance_degrees * (float)Math.PI / 180.0f;
//float closest_ang = 0;
blob winner = null;
for (int j = -1; j <= 1; j++)
{
if ((ang_index + j > -1) &&
(ang_index + j < neighbourDirections.Length))
{
// are there any neighbours in this direction?
if (neighbourDirections[ang_index + j] != null)
{
// search through all neighbours to find the one which
// has the most similar direction
for (int i = 0; i < neighbourDirections[ang_index + j].Count; i++)
{
int neighbour_index = (int)neighbourDirections[ang_index + j][i];
if ((!ignore_selected) ||
((ignore_selected) && (!((blob)neighbours[neighbour_index]).selected)))
{
float neighbour_ang = (float)angle[neighbour_index];
float ang_diff = Math.Abs(neighbour_ang - direction_radians);
if (ang_diff < max_ang_diff)
{
// this is the most similar direction yet found
//closest_ang = neighbour_ang;
max_ang_diff = ang_diff;
winner = (blob)neighbours[neighbour_index];
}
}
}
}
}
}
if ((winner != null) && (winner != this))
{
// alter the search direction slighly
// note: this might not be needed
//direction_radians = (direction_radians * 0.8f) + (closest_ang * 0.2f);
// keep note of the end point
end_point = winner;
// update the length, then carry on searching
length = 1 + winner.getDirectionalLength(direction_radians, mark_path, ignore_selected, depth + 1, max_depth, tollerance_degrees, ref end_point);
}
}
return (length);
}
/// <summary>
/// everybody needs good neighbours...
/// </summary>
/// <param name="neighbour">a neighbouring blob</param>
public void AddNeighbour(blob neighbour)
{
// update the neighbours list
neighbours.Add(neighbour);
// calculate the separation
float dist = getSeparation(neighbour);
separation.Add(dist);
// calculate the angle to this neighbour
float ang = 0;
if (dist > 0.1f)
{
float dx = neighbour.interpolated_x - interpolated_x;
float dy = neighbour.interpolated_y - interpolated_y;
ang = (float)Math.Asin(dx / dist);
if (dy < 0) ang = (float)(Math.PI * 2) - ang;
if (ang < 0) ang += (float)(Math.PI);
if (ang == float.NaN) ang = 0;
}
angle.Add(ang);
// populate the direction lookup table
int ang_index = (int)Math.Round((ang * 180 / Math.PI) / direction_increment_degrees);
if (ang_index >= neighbourDirections.Length)
ang_index = neighbourDirections.Length - 1;
if (neighbourDirections[ang_index] == null)
neighbourDirections[ang_index] = new ArrayList();
neighbourDirections[ang_index].Add(neighbours.Count-1);
}
/// <summary>
/// detect spots within the region
/// </summary>
/// <param name="black_on_white">whether this image contains darker features on a lighter background</param>
/// <param name="spot_detection_threshold">threshold used to remove low magnitude spot responses</param>
/// <param name="max_radius_variance">maximum allowable variation in spot radius</param>
/// <param name="minimum_spot_diameter_percent">minimum spot diameter as a percentage of the region height, which allows the system to ignore noise</param>
public void detectSpots(bool black_on_white,
float spot_detection_threshold,
float max_radius_variance,
float minimum_spot_diameter_percent)
{
// create a map of spottyness
spot_map = new float[width, height];
// this map will contain the positions of spot centres
// after non-maximal supression
float[,] spot_centres_map = new float[width, height];
float maximal_response = 0;
// estimate the spot radius if necessary
if (spot_radius == 0)
spot_radius = getSpotAverageRadius(black_on_white, minimum_spot_diameter_percent);
// spot radius as an integer
//int spot_radius_rounded = (int)Math.Round(spot_radius);
int spot_radius_rounded = (int)spot_radius;
// make an integral image from the binary image to speed things up
int[,] integral_image = binaryIntegralImage(black_on_white);
// apply the mask to the region of interest
for (int x = 0; x < width; x++)
{
for (int y = 0; y < height; y++)
{
int txx = x - spot_radius_rounded;
int tyy = y - spot_radius_rounded;
int bxx = x + spot_radius_rounded;
int byy = y + spot_radius_rounded;
if (txx < 0) txx = 0;
if (tyy < 0) tyy = 0;
if (bxx >= width) bxx = width - 1;
if (byy >= height) byy = height - 1;
// get the magnitude of response at this point
int spot_response_magnitude = binaryGetIntegral(integral_image, txx, tyy, bxx, byy);
// update the map using squared magnitude
int squared_magnitude = spot_response_magnitude * spot_response_magnitude;
spot_map[x, y] = squared_magnitude;
// record the maximal response
if (squared_magnitude > maximal_response)
maximal_response = squared_magnitude;
}
}
if (maximal_response > 0)
{
// errode the contours of the map (like mountains becoming weathered)
// this helps to eliminate plateau regions where the
// response is locally maximum
// erode horizontally
for (int y = 1; y < height; y++)
{
float prev_spot_value = 0;
for (int x = 1; x < width; x++)
{
float spot_value = spot_map[x, y];
float new_spot_value = prev_spot_value + ((spot_value - prev_spot_value) / 2);
spot_map[x, y] = new_spot_value;
prev_spot_value = new_spot_value;
}
}
// erode vertically
maximal_response = 0;
for (int x = 1; x < width; x++)
{
float prev_spot_value = 0;
for (int y = 1; y < height; y++)
{
float spot_value = spot_map[x, y];
float new_spot_value = prev_spot_value + ((spot_value - prev_spot_value) / 2);
spot_map[x, y] = new_spot_value;
prev_spot_value = new_spot_value;
// find the maximal response, which will allow
// subsequent normalisation
if (new_spot_value > maximal_response)
maximal_response = new_spot_value;
}
}
// normalise spot responses, and apply threshold to spot centres map
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
{
float spot_value = spot_map[x, y] / maximal_response;
spot_centres_map[x, y] = spot_value;
spot_map[x, y] = spot_value;
if (spot_value < spot_detection_threshold)
spot_centres_map[x, y] = 0;
}
// perform non-maximal supression
int supression_radius = (int)(spot_radius * 19 / 10);
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
{
if (spot_centres_map[x, y] > 0)
{
bool killed = false;
int xx = x - supression_radius;
while ((xx <= x + supression_radius) && (!killed))
{
if ((xx > -1) && (xx < width))
{
int yy = y - supression_radius;
while ((yy <= y + supression_radius) && (!killed))
{
if ((yy > -1) && (yy < height))
{
if (!((xx == x) && (yy == y)))
{
if (spot_centres_map[x, y] >= spot_centres_map[xx, yy])
spot_centres_map[xx, yy] = 0;
else
{
spot_centres_map[x, y] = 0;
killed = true;
}
}
}
yy++;
}
}
xx++;
}
}
}
// store the spot centres in a list
spots = new ArrayList();
for (int x = 0; x < width; x++)
for (int y = 0; y < height; y++)
if (spot_centres_map[x, y] > 0)
{
blob new_spot = new blob(x, y);
spots.Add(new_spot);
}
// sub-pixel interpolate spot positions
for (int i = 0; i < spots.Count; i++)
{
blob spot = (blob)spots[i];
float interpolated_x = 0;
float interpolated_y = 0;
float interpolated_total = 0;
for (int x = (int)spot.x - 1; x <= (int)spot.x + 1; x++)
{
if ((x > -1) && (x < width))
{
for (int y = (int)spot.y - 1; y <= (int)spot.y + 1; y++)
{
if ((y > -1) && (y < height))
{
float map_value = spot_map[x, y];
map_value *= map_value;
interpolated_total += map_value;
interpolated_x += (map_value * x);
interpolated_y += (map_value * y);
}
}
}
}
if (interpolated_total > 0)
{
interpolated_x /= interpolated_total;
interpolated_y /= interpolated_total;
spot.interpolated_x = interpolated_x;
spot.interpolated_y = interpolated_y;
}
}
// detect radii
detectSpotRadii(max_radius_variance);
}
}
/// <summary>
/// returns a list of spots arranged in a line between the two given spots
/// </summary>
/// <param name="spot1">the first spot</param>
/// <param name="spot2">the second spot</param>
/// <param name="max_distance">the maximum perpendicular distance below which the spot is considered to touch the line, in the range, typically in the range 0.0-1.0 as a fraction of the spot radius</param>
/// <returns></returns>
private ArrayList SpotsConnected(blob spot1, blob spot2, float max_distance, ref float average_separation)
{
return (SpotsIntersectWithLine(spot1.interpolated_x, spot1.interpolated_y, spot2.interpolated_x, spot2.interpolated_y, max_distance, ref average_separation));
}
public int getDirectionalLength(float direction_radians,
bool mark_path,
bool ignore_selected,
int depth, int max_depth,
float tollerance_degrees,
ref blob end_point)
{
int length = 0;
// mark the path if necessary
if (mark_path)
{
selected = true;
}
if (depth < max_depth)
{
// get the index of the lookup table for this direction
int ang_index = (int)Math.Round((direction_radians * 180 / Math.PI) / direction_increment_degrees);
if (ang_index >= neighbourDirections.Length)
{
ang_index -= neighbourDirections.Length;
}
// search for neighbours in this direction
float max_ang_diff = tollerance_degrees * (float)Math.PI / 180.0f;
//float closest_ang = 0;
blob winner = null;
for (int j = -1; j <= 1; j++)
{
if ((ang_index + j > -1) &&
(ang_index + j < neighbourDirections.Length))
{
// are there any neighbours in this direction?
if (neighbourDirections[ang_index + j] != null)
{
// search through all neighbours to find the one which
// has the most similar direction
for (int i = 0; i < neighbourDirections[ang_index + j].Count; i++)
{
int neighbour_index = (int)neighbourDirections[ang_index + j][i];
if ((!ignore_selected) ||
((ignore_selected) && (!((blob)neighbours[neighbour_index]).selected)))
{
float neighbour_ang = (float)angle[neighbour_index];
float ang_diff = Math.Abs(neighbour_ang - direction_radians);
if (ang_diff < max_ang_diff)
{
// this is the most similar direction yet found
//closest_ang = neighbour_ang;
max_ang_diff = ang_diff;
winner = (blob)neighbours[neighbour_index];
}
}
}
}
}
}
if ((winner != null) && (winner != this))
{
// alter the search direction slighly
// note: this might not be needed
//direction_radians = (direction_radians * 0.8f) + (closest_ang * 0.2f);
// keep note of the end point
end_point = winner;
// update the length, then carry on searching
length = 1 + winner.getDirectionalLength(direction_radians, mark_path, ignore_selected, depth + 1, max_depth, tollerance_degrees, ref end_point);
}
}
return(length);
}
