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Re: Find Area of Selection

__/ [derek] on Monday 07 November 2005 01:58 \__

> Hey all... as a research assistant I get all the fun work that the big
> boys don't want to do :)  They've asked me to take pictures of the
> fracture surface of some samples and find the area fraction of voids in
> the surface.  The pictures are mostly grayish with black circles (the
> black circles indicate void growth).
> My question is... does anyone know an easy way for me to measure the
> total area of all the 'black circles'?  I was thinking that using a
> graphics program might get me going, but other than adding a grid and
> guesstimating the amount of area that each grid has filled with
> voids... i'm pretty lost.
> Thanks fort the help in advance, ta-ta.
> ~Derek

How  about  inputting the image file/s to a general graphics file  loader,
then  counting the number of pixels that are black, i.e. go past a certain
threshold  which you can infer from the histogram? I don't think a graphi-
cal  toolbox would be most helpful in this circumstance*. When you want to
set add grids to your image, however, have a look at:

(New Image) -> Context menu -> Script-Fu -> Render - Make Grid System...

If  you want to overlay the resulting grid and put it atop an image,  make
sure you render the grid over transparent background.

Hope it helps,


*From experience, in academia it's quite hard to tell people that you used
something called GIMP as a tool.

Roy S. Schestowitz      |    while (sig==sig) sig=!sig;
http://Schestowitz.com  |    SuSE Linux     |     PGP-Key: 0x74572E8E

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