Best way to find a particle's width?

[Tentotheminus9]

I have a VI that tracks a particle's position to subpixel accuracy using the centroid function. However, I am also using the Particle Report function and using the 'width' for the width value, but this is only accurate to 1 pixel. Whats the best way to get the width (i.e. diameter) to subpixel accuracy?

[chilly_charly]

Depending on the particle shape, you can use an equivalent diameter, calculated either from the particle perimeter or area. Look at the definitions of the Hydraulic radius or Waddel disk diameter? See also the equivalent ellipse minor diameter.