Nearest Neighbor、Bilinear、Bicubic算法的Delp…

unit BitmapResize;

interface

uses
Windows, Classes, SysUtils, Graphics;

const PixelCountMax = 32768;

type
PRGBTripleArray = ^TRGBTripleArray;
TRGBTripleArray = array [0..PixelCountMax - 1] of TRGBTriple;

procedure ResizeBicubic(Src: TBitmap; var Dest: TBitmap;
DestWidth, DestHeight, SrcWidth, SrcHeight: integer);

procedure ResizeBilinear(Src: TBitmap; var Dest: TBitmap;
DestWidth, DestHeight, SrcWidth, SrcHeight: integer);

procedure ResizeNearestNeighbor(Src: TBitmap; var Dest: TBitmap;
DestWidth, DestHeight, SrcWidth, SrcHeight: integer);

implementation

function Sinc(x: double): double;
begin
if abs(x) < 1 then
Result := 1 - 2 * x * x x * x * abs(x)
else if (abs(x) >= 1) and (abs(x) < 2) then
Result := 4 - 8 * abs(x) 5 * x * x - x * x * abs(x)
else Result := 0;
end;

procedure Bicubic(I1, I2, I3, I4: TRGBTriple; var New: TRGBTriple; u: double);
var
t: integer;
begin
t := trunc(I1.rgbtRed * Sinc(u 1) I2.rgbtRed
* Sinc(u) I3.rgbtRed * Sinc(u - 1) I4.rgbtRed * Sinc(u - 2));
if t > 255 then t := 255;
if t < 0 then t := 0;
New.rgbtRed := Byte(t);

t := trunc(I1.rgbtGreen * Sinc(u 1) I2.rgbtGreen
* Sinc(u) I3.rgbtGreen * Sinc(u - 1) I4.rgbtGreen * Sinc(u - 2));
if t > 255 then t := 255;
if t < 0 then t := 0;
New.rgbtGreen := Byte(t);

t := trunc(I1.rgbtBlue * Sinc(u 1) I2.rgbtBlue
* Sinc(u) I3.rgbtBlue * Sinc(u - 1) I4.rgbtBlue * Sinc(u - 2));
if t > 255 then t := 255;
if t < 0 then t := 0;
New.rgbtBlue := Byte(t);
end;

procedure ResizeBicubic(Src: TBitmap; var Dest: TBitmap;
DestWidth, DestHeight, SrcWidth, SrcHeight: integer);
var
hScale, wScale: double;
f1, f2, f3, f4, fNew: TRGBTriple;
temp1, temp2, temp3, temp4, tempDst: PRGBTripleArray;
x, y, u, v: double;
x1, x2, x3, x4, y1, y2, y3, y4, i, j, tempRGB: integer;
begin
Dest := TBitmap.Create;
Dest.PixelFormat := pf24Bit;
Dest.Width := DestWidth;
Dest.Height := DestHeight;

Src.PixelFormat := pf24Bit;
Src.Width := SrcWidth;
Src.Height := SrcHeight;

hScale := DestHeight / SrcHeight;
wScale := DestWidth / SrcWidth;

for i := 0 to DestHeight - 1 do
begin
x := i / hScale;
x2 := trunc(x);
x1 := x2 - 1;
x3 := x2 1;
x4 := x2 2;
if x1 < 0 then x1 := 0;
if x3 > SrcHeight - 1 then x3 := SrcHeight - 1;
if x4 > SrcHeight - 1 then x4 := SrcHeight - 1;

temp1 := Src.ScanLine[x1];
temp2 := Src.ScanLine[x2];
temp3 := Src.ScanLine[x3];
temp4 := Src.ScanLine[x4];
tempDst := Dest.ScanLine[i];

v := x - x2;

for j := 0 to DestWidth - 1 do
begin
y := j / wScale;
y2 := trunc(y);
y1 := y2 - 1;
y3 := y2 1;
y4 := y2 2;
if y1 < 0 then y1 := 0;
if y3 > SrcWidth - 1 then y3 := SrcWidth - 1;
if y4 > SrcWidth - 1 then y4 := SrcWidth - 1;

u := y - y2;

Bicubic(temp1^[y1], temp1^[y2], temp1^[y3], temp1^[y4], f1, u);
Bicubic(temp2^[y1], temp2^[y2], temp2^[y3], temp2^[y4], f2, u);
Bicubic(temp3^[y1], temp3^[y2], temp3^[y3], temp3^[y4], f3, u);
Bicubic(temp4^[y1], temp4^[y2], temp4^[y3], temp4^[y4], f4, u);
Bicubic(f1, f2, f3, f4, fNew, v);

tempDst^[j] := fNew;
end;
end;
end;

procedure ResizeBilinear(Src: TBitmap; var Dest: TBitmap;
DestWidth, DestHeight, SrcWidth, SrcHeight: integer);
var
hScale, wScale: double;
f1, f2, f3, f4, f12, f34, fNew: TRGBTriple;
temp1, temp2, tempDst: PRGBTripleArray;
x, y: double;
x1, x2, y1, y2, i, j: integer;
begin
Dest := TBitmap.Create;
Dest.PixelFormat := pf24Bit;
Dest.Width := DestWidth;
Dest.Height := DestHeight;

Src.PixelFormat := pf24Bit;
Src.Width := SrcWidth;
Src.Height := SrcHeight;

hScale := DestHeight / SrcHeight;
wScale := DestWidth / SrcWidth;

for i := 0 to DestHeight - 1 do
begin
x := i / hScale;
x1 := trunc(x);
x2 := x1 1;
if x2 > SrcHeight - 1 then x2 := SrcHeight - 1;

temp1 := Src.ScanLine[x1];
temp2 := Src.ScanLine[x2];
tempDst := Dest.ScanLine[i];

for j := 0 to DestWidth - 1 do
begin
y := j / wScale;
y1 := trunc(y);
y2 := y1 1;
if y2 > SrcWidth - 1 then y2 := SrcWidth - 1;

f1 := temp1^[y1];
f2 := temp1^[y2];
f3 := temp2^[y1];
f4 := temp2^[y2];

f12.rgbtRed := trunc(f1.rgbtRed (y - y1) * (f2.rgbtRed - f1.rgbtRed));

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