On Sun, Mar 27, 2016 at 08:29:05PM +0200, Václav Šmilauer wrote: > I am new to Gwyddion and would like to try using it for grain size > analysis from industrial camera images. A typical image is like this: > http://i.imgur.com/lwuOBeh.jpg (the diagonal separates two types of > material which has different reflectivity), and I would like to run (at > some point) unattended analysis of grain size distribution under > constant conditions (same lighting, similar material). > > I was able to use some of the tools provided to improve the picture > (like Polynomial Background to make the lighting artefacts less visible) > but I am at loss with segmentation. The simple techniques (e.g. > watershed) are not suitable, since grains have different luminosity > (especially the glossy ones).
The image is a photograph, i.e. intensity does not correspond to height, which is somewhat outside Gwyddion's focus. Anyway, the first step would be a strong local equalisation filter. I would use something like Presentation → Rank with a reasonable radius (25 or so). Then Extract Presentation and use the result as your data. Then it depends... I do not even know what exactly I would mark there as a human. Since the image is grainy you can use a smoothing filter (in Filters tool), either linear Gaussian or morphological such as ACF Closing. In this moment threshold marking will give a more or less reasonable result that can be improved by Fill Voids in the Mask Editor tool or again some morphological operations with the mask (Grow with grain merging prevention, ...). You can get rid of too small and too large grains using Grains → Filter. Grains → Distributions can export selected properties of all grains as a table to some file. Regards, Yeti ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785351&iu=/4140 _______________________________________________ Gwyddion-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/gwyddion-users
