Re: Area measurements for 50 particles on one image (image attached)

Posted by John Cahill on Jun 20, 2011; 2:49pm
URL: http://imagej.273.s1.nabble.com/Area-measurements-for-50-particles-on-one-image-image-attached-tp3684189p3684191.html

Kumara,
I would recommend back-lighting with a light-box as used to view 35mm slides.
Example here: http://www.bhphotovideo.com/c/product/194987-REG/Hakuba_KLV_5700_5_x_7_Lightviewer.html
This will give a shadow free image which is simple to threshold.
The size you will measure is the "obscured" area and will depend on
how the rocks are positioned/rotated on the surface,
think of a coin either flat down or on edge.

John


On Mon, Jun 20, 2011 at 6:48 AM, janaka kumara <[hidden email]> wrote:

> Dear all,
>
> In this image, there are 50 particles. I want to measure areas for each particles but when I do using ImageJ toolbar, I don't get area measurements for all particles (50). I do analyses as follows,
>
> - Analyze, then Set Scale (to set a scale)
> - Rectangle shape selection (to remove ruler on the image)
> - Edit, then clear outside (now only particles remained on the image)
> - Process, then Find Edges
> - Process, then Binary, then Make Binary
> - Process, then Binary, then Dilate (as images are not very clear)
> - Analyze, then Analyze particles, there
>         size (mm2): 5-infinity
>         circularity: 0-1.00
>         show: outlines
>
> Then, on the result sheet, I cannot see data for exactly 50 particles.
>
> Could you please advice me on this matter?
>
> Note: due to limitation for size, image attached was resized. If you want the original image, I can give you it if you will send me your email address.
>
> Thank you.
>
> Yours sincerely,
> Kumara
>
> PhD candidate
> Geotechnical Engineering Laboratory
> Department of Civil Engineering
> Yokohama National University, Japan