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Re^3: Detect boundaries within .png's - and cropping

by etj (Deacon)
on Apr 25, 2022 at 01:57 UTC ( [id://11143251]=note: print w/replies, xml ) Need Help??


in reply to Re^2: Detect boundaries within .png's - and cropping
in thread Detect boundaries within .png's - and cropping

It turns out that making this broadcast properly over multiple images was impressively hard.

which had a hardcoded limitation that it would only work on a 1-dim ndarray (fixed by imitating PDL::VectorValued's strategy of having a "how many set for each vector" output ndarray).

Then actually using that with minmaximum also posed a problem, since the number of values per image might vary (in other words, the outputs might be ragged) - fixed that by having which fill the unset index-values with -1, and then setting that as the badvalue for the output ndarray, so minmaximum would ignore them.

After that, the rest was easy! The new PDL::Image2D::crop works on a mask, so the above snippet would call

$x1x2y1y2 = ($img->slice('(3)') != 0)->crop;

Replies are listed 'Best First'.
Re^4: Detect boundaries within .png's - and cropping
by etj (Deacon) on May 03, 2022 at 20:35 UTC
    This has now been released with PDL 2.079! See separate announcement for more.

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