I'm not sure what you mean by "engage porosity into the image", but
"...so I started with a simple x,y loop" is almost certainly why it is
so slow. If you are doing image processing with a Perl loop, pulling
individual pixel values into and out of a PDL, it will be at least
100x slower than doing the same job with the threading engine.
Since you mention trying to select stuff from a range in color space,
here's a simple example. Here I assume your image is arranged in (X,
Y, RGB) format -- i.e. the dimensions are WxHx3, as would be returned
by rim().
$im = rim("myimage.png"); # or whatever -- get your image into a
variable
$color = pdl(128,200,128); # light green for 8-bit RGB
#####
# Generate a list of all pixels with a certain color
$imt = $im->mv(2,0); # (RGB, X, Y)
$mask = all($imt==$color); # (X, Y) mask -- collapsed over RGB
dimension
$wh_exact = $mask->whichND; # (2 x N) -- coordinates of all
matching points
#####
# Generate a list of all pixels within a 3-D "slop distance" in RGB
space
# of a certain color
$slop = 7;
$dist_sq = (($im-$color)*($im-$color))->sumover; # (X,Y) distance
image -- collapsed over RGB
$mask = ($dist_sq <= $slop*$slop); # mask of
matching pixels
$wh_sloppy = $mask->whichND; # (2 x M) -- coordinates of all
matching points
Does that help?
On May 6, 2011, at 10:01 AM, Luca Cappelletti wrote:
Hello *
I've a performance problem using a simple scan line flood fill image
with perl.
With 800x600 colour pictures coming from SEM microanalisys I would
like to engage porosity into the image so I started with a simple
x,y loop.
The problem here is that requires too much seconds to scan and
produce the new colored image.
At the moment I use imlib2 to read and write pixel color.
I'm new to PDL and I cannot believe that it's true...it's so
powerful!!
I don't how can I use PDL to speed up my scan.
Do you know how to flood fill images or count porosity, engage color
range and so on?
I can use boolean intersection between 2 sets, the firs my picture
the second a color mask but this close to 1 color, I've a range to
parse because I have to take into account the error (like the fuzzy
option in magickperl floodfill), that will be: my picked pixel color
+/- error range so I don't understand how to use matrix solution.
May you help me please?
Thank you in advance,
Luca
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