There are some additions in 8.1 and 8.5 that make this type of analysis possible. Specifically, contour plots in 8.1 added a context menu to extract contour lines as data, and 8.5 added a polyarea function.
So to do this in 8.5 ...
(1) Import the image.
(2) Use the Image : Conversion : Threshold function to clean up the image a bit(an Upper Bound of 160 seemed to work well).
(3) Plot the image as a Color Contour.
(4) Set the color Levels to 1 and adjust the Z value to get a clean separation of image and background (4.2E4 seemed to work well).
(5) Right-click on the plot and choose Extract Contours.
The first two columns are just the boundary of the contour plot while the next two columns contains the contour data which will be separated by missing values for each contour set which in this case means each 'blob' in the image.
The above can be done in 8.1. The rest requires 8.5:
(6) Run this script
// BEGIN SCRIPT
double MyArea;
int iStart = 1;
int iRow = 1;
wks.Addcol(Area);
range ra = col(4);
loop(idx,1,ra.GetSize())
{
if(ra[idx] == 0/0)
{
iEnd = idx - 1;
polyarea iy:=(3,4)[iStart:iEnd] type:=1 area:=MyArea;
col(Area)[iRow] = MyArea;
iStart = idx + 1;
iRow++;
}
}
range raO = col(Area);
ty $(rao.GetSize()) objects found with total area $(total(raO));
// END SCRIPT
(7) Plot a Histogram of the Area column
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size analysing of mosaic image
Posted - 02/15/2011 : 08:26:13 AM
