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Update package.d doc for median filter example #468

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Apr 8, 2024
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Update package.d doc for median filter example #468

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32 changes: 22 additions & 10 deletions source/mir/ndslice/package.d
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Original file line number Diff line number Diff line change
Expand Up @@ -360,8 +360,8 @@ Returns:
where с is the number of channels in the image.
Dense data layout is guaranteed.
+/
Slice!(ubyte*, 3) movingWindowByChannel
(Slice!(Universal, [3], ubyte*) image, size_t nr, size_t nc, ubyte delegate(Slice!(Universal, [2], ubyte*)) filter)
Slice!(C*, 3) movingWindowByChannel(alias filter, C)
(Slice!(C*, 3, Universal) image, size_t nr, size_t nc)
{
// 0. 3D
// The last dimension represents the color channel.
Expand All @@ -374,10 +374,12 @@ Slice!(ubyte*, 3) movingWindowByChannel
.windows(nr, nc)
// 3. 5D
// Unpacks the windows.
.unpack
.transposed!(0, 1, 4)
.unpack.unpack
// 4. 5D
// Brings the color channel dimension to the third position.
.transposed!(0, 1, 4)
// 5. 3D Composed of 2D
// Packs the last two dimensions.
.pack!2
// 2D to pixel lazy conversion.
.map!filter
Expand All @@ -397,12 +399,15 @@ Params:
Returns:
median value over the range `r`
+/
T median(Range, T)(Slice!(Universal, [2], Range) sl, T[] buf)
T median(Iterator, SliceKind kind, T)(Slice!(Iterator, 2, kind) sl, T[] buf)
{
import std.algorithm.sorting : topN;
// copy sl to the buffer
auto retPtr = reduce!(
(ptr, elem) { *ptr = elem; return ptr + 1;} )(buf.ptr, sl);
(ptr, elem) {
*ptr = elem;
return ptr + 1;
} )(buf.ptr, sl);
auto n = retPtr - buf.ptr;
buf[0 .. n].topN(n / 2);
return buf[n / 2];
Expand All @@ -414,9 +419,9 @@ The `main` function:
-------
void main(string[] args)
{
import std.conv : to;
import std.getopt : getopt, defaultGetoptPrinter;
import std.path : stripExtension;
import std.conv: to;
import std.getopt: getopt, defaultGetoptPrinter;
import std.path: stripExtension;

uint nr, nc, def = 3;
auto helpInformation = args.getopt(
Expand All @@ -434,6 +439,12 @@ void main(string[] args)

auto buf = new ubyte[nr * nc];

if (args.length == 1)
{
import std.stdio: writeln;
writeln("No input file given");
}

foreach (name; args[1 .. $])
{
import imageformats; // can be found at code.dlang.org
Expand All @@ -442,6 +453,7 @@ void main(string[] args)

auto ret = image.pixels
.sliced(cast(size_t)image.h, cast(size_t)image.w, cast(size_t)image.c)
.universal
.movingWindowByChannel
!(window => median(window, buf))
(nr, nc);
Expand All @@ -450,7 +462,7 @@ void main(string[] args)
name.stripExtension ~ "_filtered.png",
ret.length!1,
ret.length!0,
(&ret[0, 0, 0])[0 .. ret.elementCount]);
ret.field);
}
}
-------
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