Hi Russel,
if you draw a polygon selection, you can may want Edit>Selection>Add to
Manager (shift-T) to keep it; then you can draw a new selection without
losing the first one. Later on, in the ROI Manager (ROI = region of
interst = selection), you can combine all selections to a single one for
measuring, or select all selections and use the ROI Manager's 'Measure',
or do something else that you like...
Not that the measurements done depend on the settings of Analyze>Set
Measurements.
See the documentation on the ImageJ homepage for details...
For automatic segmentation of images, there are thousands of methods and
tricks.
Typically, first you need to flatten the image in case of uneven
illumination, then you may need some edge-preserving blur to reduce noise.
If you are lucky, you can then use Image>Adjust>Threshold.
Michael
____________________________________________________________________
On Tue, December 24, 2013 20:30, Russell Swift wrote:
> Hi,
>
>
> I'm just starting out with Image J, and am finding the amount of
> information on the programme a bit overwhelming after trying to work my
> way through some of it.
>
>
> I'm planning on using the software to analyse 2D images of rocks in thin
> section. Basically I need to be able to trace around grains, pores, and
> pore connections and then analyse their shapes, sizes and size
> distributions. However, I'm struggling at the moment to trace around the
> grains as the polygons I make just disappear.
>
>
> If anyone could advise me, point me towards any relevant information or
> recommend any plug-ins that you think I may need, then I would be very
> thankful.
>
>
> Regards,
>
>
> Russell
>
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