How do I draw a line that has an origin coord but ends when it hits white (ie 255)?

[Nikolas Jorstad]

Hello,
 
My name is Nik and I am attempting to make a macro for quantifying human
 myelin thickness around axons in the optic nerve. I am able to do all the
 image processing necessary but am hitting a dead end on the final leg of
 the script.
 
My final image is in binary and looks like different shaped rings of
 different thicknesses. I need code that will draw a line, starting at the
 inner Feret Diameter, following the Feret Angle outwards until it hits the
 white background. In essence, the drawn lines will measure the thickness of
 these oblong loops. I am only aware of being able to draw a line from
 (X1,Y1) to (X2,Y2). Is there anyway to give the line a starting point and
 have it follow the Feret Angle until it hits color value = 255 (white)?
 
Thank you to anyone who may be able to help.
 

Nik
 

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[Peter van Loon]

Hi Nik, I'm not sure if I understand your question well (a picture may help). Maybe this code can help: To draw a line based on a center coordinate and angle: function makeLineC(centerX, centerY, length, angle) { angle = -angle * PI / 180; dX = cos(angle) * length / 2; dY = sin(angle) * length / 2; makeLine(centerX - dX, centerY - dY, centerX + dX, centerY + dY); } To draw a line based on an end coordinate and angle: function makeLineE(centerX, centerY, length, angle) { angle = -angle * PI / 180; dX = cos(angle) * length / 2; dY = sin(angle) * length / 2; makeLine(centerX, centerY, centerX + dX, centerY + dY); } By measuring the black and white(255) pixels you can use this function: function countMinMax(){ profileValues=getProfile(); Array.getStatistics(profileValues, min, max, mean, stdDev); countMin = 0; countMax = 0; for(i=0;i<lengthOf(profileValues);i++){ if (profileValues[i]==0) { countMin = countMin+1;} if (profileValues[i]==max) { countMax = countMax+1;} } }</i>By measuring the number of 0 (countMin) and 255 (countMax) values you can calculate the thickness. Regards, Peter

[Peter van Loon]

Hi Nik,

I'm not sure if I understand your question well (a picture may help).

Maybe this code can help:
To draw a line based on a center coordinate and angle:
function makeLineC(centerX, centerY, length, angle) {
        angle = -angle * PI / 180; dX = cos(angle) * length / 2; dY = sin(angle) * length / 2;
        makeLine(centerX - dX, centerY - dY, centerX + dX, centerY + dY);
}
To draw a line based on an end coordinate and angle:
function makeLineE(centerX, centerY, length, angle) {
       angle = -angle * PI / 180; dX = cos(angle) * length / 2; dY = sin(angle) * length / 2;
        makeLine(centerX, centerY, centerX + dX, centerY + dY);
}

By measuring the black and white(255) pixels you can use this function:
function countMinMax(){
  profileValues=getProfile(); Array.getStatistics(profileValues, min, max, mean, stdDev);
  countMin = 0; countMax = 0;
  for(i=0;i<lengthOf(profileValues);i++){
  if (profileValues[i]==0) { countMin = countMin+1;}
  if (profileValues[i]==max) { countMax = countMax+1;}
  }
 }
By measuring the number of 0 (countMin) and 255 (countMax) values you can calculate the thickness.

Regards,
Peter