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RGB颜色空间与YUV等颜色空间之间的转换单元

时间:2011-9-3 15:03:33 点击:

  核心提示:unit RGBYUV;interfaceuses Windows,Classes,Graphics,Math;function RGBToColor(R,G,B: Byte): TColor;ove...

unit RGBYUV;

interface
uses Windows,Classes,Graphics,Math;
function RGBToColor(R,G,B: Byte): TColor;overload;
function RGBToColor(Color : Longint): TColor;overload;

procedure ColorToYUV(RGB: TColor; out Y, Cb, Cr: byte);
function YUVtoColor(Y, Cb, Cr: Byte): TColor;
implementation

function RGBToColor(R,G,B: Byte): TColor;
begin
  Result := R or (G shl 8) or (B shl 16);
end;

function RGBToColor(Color : Longint): TColor;
var
  R,G,B,A : Byte;
begin
  R := Color and $FF;
  G := (Color shr 8) and $FF;
  B := (Color shr 16) and $FF;
  A := $00;
  Result := R or (G shl 8) or (B shl 16) or (A shl 24);
end;

procedure ColorToRGB(Color: TColor; out R, G, B: Byte);
begin
  R := Color and $FF;
  G := (Color shr 8) and $FF;
  B := (Color shr 16) and $FF;
end; procedure ColorToCMY(Color: TColor; out C, M, Y: Byte);
var
  R,G,B : Byte;
begin
  ColorToRGB(Color, R, G, B);
  C := 255 - R;
  M := 255 - G;
  Y := 255 - B;
end; function CMYToColor(C, M, Y: Byte): TColor;
begin
  Result := (255 - C) or ((255 - M) shl 8) or ((255 - Y) shl 16);
end; function HSLtoColor(H, S, L: Double): TColor;
var
  M1, M2: double;
  function HueToColourValue (Hue: double) : byte;
  var
    V : double;
  begin
    if Hue < 0 then
      Hue := Hue + 1
    else
      if Hue > 1 then
        Hue := Hue - 1;

    if 6 * Hue < 1 then
      V := M1 + (M2 - M1) * Hue * 6
    else
      if 2 * Hue < 1 then
        V := M2
      else
        if 3 * Hue < 2 then
          V := M1 + (M2 - M1) * (2/3 - Hue) * 6
        else
          V := M1;
    Result := round (255 * V)
  end;
var
  R, G, B: byte;
begin
  if S = 0 then
  begin
    R := round (255 * L);
    G := R;
    B := R
  end
  else
  begin
    if L <= 0.5 then
      M2 := L * (1 + S)
    else
      M2 := L + S - L * S;
    M1 := 2 * L - M2;
    R := HueToColourValue (H + 1/3);
    G := HueToColourValue (H);
    B := HueToColourValue (H - 1/3)
  end;
  Result := RGB (R, G, B)
end;
procedure ColortoHSL(RGB: TColor; out H, S, L: double);
var
  R, G, B : double;
  D, Cmax, Cmin: double;
begin
  R := GetRValue (RGB) / 255;
  G := GetGValue (RGB) / 255;
  B := GetBValue (RGB) / 255;
  Cmax := Max (R, Max (G, B));
  Cmin := Min (R, Min (G, B));
  // calculate luminosity
  L := (Cmax + Cmin) / 2;
  if Cmax = Cmin then
  begin
    H := 0;// it's actually undefined
    S := 0;
  end
  else
  begin
    D := Cmax - Cmin;
    // calculate Saturation
    if L < 0.5 then
      S := D / (Cmax + Cmin)
    else
      S := D / (2 - Cmax - Cmin);

    // calculate Hue
    D_R := (((Cmax - R) / 6) + (D / 2)) / D;
    D_G := (((Cmax - G) / 6) + (D / 2)) / D;
    D_B := (((Cmax - B) / 6) + (D / 2)) / D;

    if      R = Cmax then  H := (D_B - D_G)
    else if G = Cmax then  H := (1 / 3) + D_R - D_B
    else if B = Cmax then  H := (2 / 3) + D_G - D_R;

    if H < 0 then H := H + 1;
    if H > 1 then H := H - 1;
  end;
end;


procedure ColorToYUV(RGB: TColor; out Y, Cb, Cr: byte);
{
Lum (Y) ranges from 16 to 235.
Cb  (U) ranges from 16 to 240.
Cr  (V) ranges from 16 to 240.
}
var
  R,G,B : byte;
  t: Double;
begin
  R := GetRValue(RGB);
  G := GetGValue(RGB);
  B := GetBValue(RGB);

  Y  := Round( (0.257 * R) + (0.504 * G) + (0.098 * B) + 16 );
  Cb := Round( (-0.148 * R) - (0.291 * G) + (0.439 * B) + 128 );
  Cr := Round( (0.439 * R) - (0.368 * G) - (0.071 * B) + 128 );
  {y := Round(0.299*R + 0.587*G + 0.114*B);
  Cb := Round(0.564*(B - Y ));
  Cr := Round(0.713*(R - Y )) }
end;  
function YUVtoColor(Y, Cb, Cr: Byte): TColor;
{
Lum (Y) ranges from 16 to 235.
Cb  (U) ranges from 16 to 240.
Cr  (V) ranges from 16 to 240.
}
var
  R,G,B: Byte;
begin
  G := Round( (1.164 * (Y-16)) - (0.391 * (Cb-128)) - (0.813 * (Cr-128)) );
  R := Round( (1.164 * (Y-16)) + (1.596 * (Cr-128)) );
  B := Round( (1.164 * (Y-16)) + (2.018 * (Cb-128)) );

  Result := RGBToColor(R, G, B);
end;  
end.

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