Re: Thresholding help

Posted by Justin Walker-3 on Oct 29, 2008; 8:57pm
URL: http://imagej.273.s1.nabble.com/Thresholding-help-tp3694620p3694626.html

While inverting it does make the droplets appear bright on a dark
background, it doesn't change the overall contrast, so it really doesn't
help in terms of locating the droplets for thresholding.  I need
something like the 'find edges' plugin, but with a higher sensitivity.

- Justin

Fabrice Senger wrote:

> Quoting Justin Walker <[hidden email]>:
>
>> I have a series of images of liquid droplets, which have very poor
>> contrast with the surrounding phase, due to the similarities in their
>> index of refraction.  I get enough contrast in my images to clearly see
>> the droplets, however, I can't pick them out with the threshold because
>> there is a slight gradient in the brightness of my lighting.  Link to a
>> sample image is below:
>>
>> http://www.chejrw.com/forum/test.tif
>>
>> Does anyone know of a way I can manipulate this image to be able to use
>> the 'measure particles' plugin to get the droplet sizes?  I can clearly
>> see the droplets, so surely there must be a way to make the computer
>> see them.
>>
>> Thanks everybody
>>
>> - Justin Walker
>
> As far I can see in your images, you can see the "contour" of the
> droplets.
> If you invert your image, this "contour" should appear bright in a
> dark background.
>
> This should help.
>
> Fabrice.