Median filter: Difference between revisions
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→{{header|Wren}}: Changed to Wren S/H
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}</syntaxhighlight>
Compile with -version=median_filter_main to run the demo.
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
[[File:DelphiMedianFilter.png|frame|none]]
<syntaxhighlight lang="Delphi">
{-------------------------------------------------------------------------------}
type THistogram = record
Bins: array [0..255] of integer;
Colors: array [0..255] of TRGBTriple;
end;
procedure MedianFilter(Src,Dest: TBitmap; WindowX, WindowY: integer);
var x, y, X1, Y1, med, md, dl, delta_l, WX2, WY2: integer;
var I, MedSum, XStart,XEnd, YStart,YEnd, MedInx: integer;
var middle: integer;
var Histogram: THistogram;
var u: byte;
var Color: TRGBTriple;
var SrcRows,DestRows: TRGBTripleRowArray;
begin
WindowX:=WindowX * 2 -1;
WindowY:=WindowY * 2 -1;
Src.PixelFormat:=pf24Bit;
Dest.PixelFormat:=pf24Bit;
Dest.Width:=Src.Width;
Dest.Height:=Src.Height;
SetLength(SrcRows,Src.Height);
SetLength(DestRows,Dest.Height);
{Capture scan lines of both source and destiantion bitmaps}
for Y:=0 to Src.Height-1 do SrcRows[Y]:=Src.ScanLine[Y];
for Y:=0 to Dest.Height-1 do DestRows[Y]:=Dest.ScanLine[Y];
WX2 := WindowX div 2;
WY2 := WindowY div 2;
middle := (WindowX * WindowY-1) div 2;
for y := 0 to SRC.Height-1 do
begin
{ Determine the histogram and median for the first element of each row}
YStart:=Y - WY2;
YEnd:=Y + WY2;
{ histogram reset }
for I := 0 to 255 do Histogram.Bins[I] := 0;
{recalculation of the histogram for the start element row=y, col=0 }
for Y1 := YStart to YEnd do
for X1 := -WX2 to WX2 do
begin
{It is the first pixel on the row, so don't worry about right edge}
if (Y1>=0) and (Y1<SRC.Height) and (X1>=0) then Color:=SrcRows[Y1][X1] else Color:=MakeRBGTriple(0,0,0); // Color:=SrcRows[y][0];
U:=RGBToGray(Color);
inc(Histogram.Bins[U]);
Histogram.Colors[U]:=Color;
end;
{ now determine the median }
MedSum := 0;
for MedInx := 0 to 255 do
begin
inc(MedSum,Histogram.Bins[MedInx]);
if MedSum > middle then break;
end;
med := MedInx;
delta_l := MedSum - Histogram.Bins[MedInx];
DestRows[Y][0]:=Histogram.Colors[MedInx];
{ Loop through each column in this row}
for x := 1 to Src.Width-1 do
begin
XStart := x-wx2-1;
XEnd := x+wx2;
{ go to next column }
for Y1 := YStart to YEnd do
begin
if (XStart >= 0) and (Y1 >= 0) and (Y1 < SRC.Height) then Color:=SrcRows[Y1][XStart] else Color:=MakeRBGTriple(0,0,0); // Color:=SrcRows[Y][X];
U:=RGBToGray(Color);
if Histogram.Bins[u]>0 then dec(Histogram.Bins[u]);
if u < med then dec(delta_l);
if (XEnd < Src.Width) and (Y1 >= 0) and (Y1 < SRC.Height) then Color:=SrcRows[Y1][XEnd] else Color:=MakeRBGTriple(0,0,0); // Color:=SrcRows[Y][X];
U:=RGBToGray(Color);
inc(Histogram.Bins[u]);
Histogram.Colors[U]:=Color;
if u < med then inc(delta_l);
end;
{ update new median }
dl := delta_l;
md := med;
if dl > middle then
begin
while dl > middle do
begin
dec(md);
if Histogram.Bins[md] > 0 then
dec(dl,Histogram.Bins[md]);
end;
end
else
begin
while dl + Histogram.Bins[md] <= middle do
begin
if Histogram.Bins[md] > 0 then inc(dl,Histogram.Bins[md]);
inc(md);
end;
end;
delta_l := dl;
med := md;
DestRows[Y][X]:= Histogram.Colors[med];
end; { x loop}
end; { y loop}
end;
</syntaxhighlight>
{{out}}
<pre>
Elapsed Time: 110.287 ms.
</pre>
=={{header|GDL}}==
Line 701 ⟶ 836:
public static void main(String[] aArgs) {
try {
BufferedImage image = ImageIO.read( new File("
BasicBitmapStorage bitmap = new BasicBitmapStorage(image.getWidth(null), image.getHeight(null));
Line 711 ⟶ 846:
bitmap.medianFilter(3, 3);
File fileAfterFilter = new File("
ImageIO.write((RenderedImage) bitmap.getImage(), "png", fileAfterFilter);
} catch (IOException ioe) {
Line 768 ⟶ 903:
private double luminance(Color aColor) {
return 0.2126 * aColor.getRed() + 0.7152 * aColor.getGreen() + 0.0722 * aColor.
}
Line 775 ⟶ 910:
}
</syntaxhighlight>
{{ out }}
[[Media:beforeFilter.png]] & [[Media:afterFilter.png]]
=={{header|Julia}}==
Line 1,261 ⟶ 1,398:
{{libheader|DOME}}
This follows the Wikipedia pseudo-code for the median filter, sorting the colors by their luminance, and displays the 'before' and 'after' images side by side on the canvas. Results are as expected though remaining corruption seems more prominent than on Wikipedia image.
<syntaxhighlight lang="
import "dome" for Window
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