Ray Gilbert wrote:
I wanted to do exactly that some time ago and adapted this macro
http://rsb.info.nih.gov/ij/macros/RandomSampleAndMeasure.txt.
// RandomSampleAndMeasureWithinSelection-1step.txt
// Randomly places predefined Regions of Interest completely within
// the boundaries of a larger Region of Interest, measures and labels them
// G. Landini at bham. ac. uk and Bo de Lange
// Start with opening the image, and drawing the large ROI (MUST be
smaller than total image).
macro "RandomSampleAndMeasureWithinROI [F1]" {
run("Select None");
saveSettings();
original=getTitle();
setForegroundColor(255,0,0);
width = getWidth()-30; // width of the randomly placed ROI
height = getHeight()-30; // height of the randomly placed ROI
RoisN =50; // number of ROIs
trials=100 ; //maximum trials to avoid infinite loop
i=0;
j=0;
xa=newArray(RoisN);
ya=newArray(RoisN);
run("Duplicate...", "title=Reference");
selectWindow("Reference");
run("8-bit"); //makes it greyscale
run("RGB Color"); //RGB to display colours
run("Restore Selection");
run("Make Inverse");
run("Fill");
run("Select None");
while (i<RoisN && j<trials){
w = 30;
h = 30;
x = random()*width;
y = random()*height;
j++;
//Check for pixels with value (255,0,0):
flag= -1;
makeRectangle(x, y, w, h);
//Scanning the rectangle perimeter should be faster than
scanning the whole box.
//This is slower, as checks all the points in the box:
for (xs=x;xs<x+w;xs++){
for (ys=y;ys<y+h;ys++){
if (getPixel(xs,ys)==-65536) // pixel is (255,0,0)
flag=0;
}
}
if (flag==-1){
xa[i]=x;
ya[i]=y;
run("Fill");
i++;
}
}
close();
selectWindow(original);
setForegroundColor(255,255,0);
for (j=0;j<i;j++){
makeRectangle(xa[j], ya[j], w, h);
run("Measure");
run("Label");
}
restoreSettings();
run("Select None");
run("Jpeg...", "save");
run("Close");
}
>Is there any way in Image J to sample random regions of interest of
>fixed size within a defined area in a larger image?
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>Failing that is it possible to set the grid up within a specified area
>rather than over the entire image?
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>Thanks
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>--
>
>Ray Gilbert
>
>Senior Research Assistant
>
>Lactation Gene Expression Project
>
>Molecular and Chemical Neuroanatomy Group
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>Dept of Anatomy with Radiology
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>Faculty of Medical and Health Sciences
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>University of Auckland
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>Private Bag 92019
>
>Auckland
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>New Zealand
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>Ph 0064 9 3737 599 ext 86022
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>fax 0064 9 3737484
>
>
[hidden email] <mailto:
[hidden email]>
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>
>
>
--
R.P.J. de Lange, PhD
Rudolf Magnus Institute of Neurosciences
P.O. box 80040
3508 TA Utrecht
The Netherlands
visiting address:
Stratenum, room 4.241
Universiteitsweg 100
3584 CG Utrecht
tel: +31-30-253 8924
+31-30-253 8837 (lab)
fax: +31-30-253 9032
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