|
|
Hi,
On Feb 1, 2010, at 6:38 PM, miko wrote:
> Hello,
>
> Does anyone know of a plugin or method for thresholding based on a
> fixed
> number of pixels? e.g. the n brightest pixels within an ROI in each
> frame of a
> stack.
The macro below shows how you might select a threshold on the
cumulative histogram. It selects the threshold not on "n brightest
pixels" but a fraction of the pixels. I think you could adapt it
easily enough. Note that the example is for 8 bit - you'll need to
tweak it for other depths.
Cheers,
Ben
//BEGIN
run("AuPbSn 40 (56K)");
nBins = 256;
getHistogram(values, counts, nBins);
nThresh = 0.75; // <----- threshold fraction
cum = newArray(nBins);
cum[0] = counts[0];
tot = counts[0];
for (i=1; i<nBins;i++){
tot += counts[i];
cum[i] += tot;
}
thresh = cum[0];
i = 0;
while (thresh/tot < nThresh) {
print(i + " = " + thresh/tot + " threshold fraction");
i++;
thresh = cum[i];
}
print("Threshold=" + i);
setThreshold(0, i);
//END
|
Locked
