CentrED

{

  $Id: ImagingColors.pas 74 2007-03-12 15:04:04Z galfar $

  Vampyre Imaging Library

  by Marek Mauder 

  http://imaginglib.sourceforge.net

  The contents of this file are used with permission, subject to the Mozilla

  Public License Version 1.1 (the "License"); you may not use this file except

  in compliance with the License. You may obtain a copy of the License at

  http://www.mozilla.org/MPL/MPL-1.1.html

  Software distributed under the License is distributed on an "AS IS" basis,

  WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for

  the specific language governing rights and limitations under the License.

  Alternatively, the contents of this file may be used under the terms of the

  GNU Lesser General Public License (the  "LGPL License"), in which case the

  provisions of the LGPL License are applicable instead of those above.

  If you wish to allow use of your version of this file only under the terms

  of the LGPL License and not to allow others to use your version of this file

  under the MPL, indicate your decision by deleting  the provisions above and

  replace  them with the notice and other provisions required by the LGPL

  License.  If you do not delete the provisions above, a recipient may use

  your version of this file under either the MPL or the LGPL License.

  For more information about the LGPL: http://www.gnu.org/copyleft/lesser.html

}

{ This unit contains functions for manipulating and converting color values.}

unit ImagingColors;

interface

{$I ImagingOptions.inc}

uses

  SysUtils, ImagingTypes, ImagingUtility;

{ Converts RGB color to YUV.}

procedure RGBToYUV(R, G, B: Byte; var Y, U, V: Byte);

{ Converts YIV to RGB color.}

procedure YUVToRGB(Y, U, V: Byte; var R, G, B: Byte);

{ Converts RGB color to YCbCr as used in JPEG.}

procedure RGBToYCbCr(R, G, B: Byte; var Y, Cb, Cr: Byte);

{ Converts YCbCr as used in JPEG to RGB color.}

procedure YCbCrToRGB(Y, Cb, Cr: Byte; var R, G, B: Byte);

{ Converts RGB color to YCbCr as used in JPEG.}

procedure RGBToYCbCr16(R, G, B: Word; var Y, Cb, Cr: Word);

{ Converts YCbCr as used in JPEG to RGB color.}

procedure YCbCrToRGB16(Y, Cb, Cr: Word; var R, G, B: Word);

{ Converts RGB color to CMY.}

procedure RGBToCMY(R, G, B: Byte; var C, M, Y: Byte);

{ Converts CMY to RGB color.}

procedure CMYToRGB(C, M, Y: Byte; var R, G, B: Byte);

{ Converts RGB color to CMY.}

procedure RGBToCMY16(R, G, B: Word; var C, M, Y: Word);

{ Converts CMY to RGB color.}

procedure CMYToRGB16(C, M, Y: Word; var R, G, B: Word);

{ Converts RGB color to CMYK.}

procedure RGBToCMYK(R, G, B: Byte; var C, M, Y, K: Byte);

{ Converts CMYK to RGB color.}

procedure CMYKToRGB(C, M, Y, K: Byte; var R, G, B: Byte);

{ Converts RGB color to CMYK.}

procedure RGBToCMYK16(R, G, B: Word; var C, M, Y, K: Word);

{ Converts CMYK to RGB color.}

procedure CMYKToRGB16(C, M, Y, K: Word; var R, G, B: Word);

implementation

procedure RGBToYUV(R, G, B: Byte; var Y, U, V: Byte);

begin

  Y := ClampToByte(Round( 0.257 * R + 0.504 * G + 0.098 * B) + 16);

  V := ClampToByte(Round( 0.439 * R - 0.368 * G - 0.071 * B) + 128);

  U := ClampToByte(Round(-0.148 * R - 0.291 * G + 0.439 * B) + 128);

end;

procedure YUVToRGB(Y, U, V: Byte; var R, G, B: Byte);

var

  CY, CU, CV: LongInt;

begin

  CY := Y - 16;

  CU := U - 128;

  CV := V - 128;

  R := ClampToByte(Round(1.164 * CY - 0.002 * CU + 1.596 * CV));

  G := ClampToByte(Round(1.164 * CY - 0.391 * CU - 0.813 * CV));

  B := ClampToByte(Round(1.164 * CY + 2.018 * CU - 0.001 * CV));

end;

procedure RGBToYCbCr(R, G, B: Byte; var Y, Cb, Cr: Byte);

begin

  Y  := ClampToByte(Round( 0.29900 * R + 0.58700 * G + 0.11400 * B));

  Cb := ClampToByte(Round(-0.16874 * R - 0.33126 * G + 0.50000 * B  + 128));

  Cr := ClampToByte(Round( 0.50000 * R - 0.41869 * G - 0.08131 * B  + 128));

end;

procedure YCbCrToRGB(Y, Cb, Cr: Byte; var R, G, B: Byte);

begin

  R := ClampToByte(Round(Y                        + 1.40200 * (Cr - 128)));

  G := ClampToByte(Round(Y - 0.34414 * (Cb - 128) - 0.71414 * (Cr - 128)));

  B := ClampToByte(Round(Y + 1.77200 * (Cb - 128)));

end;

procedure RGBToYCbCr16(R, G, B: Word; var Y, Cb, Cr: Word);

begin

  Y  := ClampToWord(Round( 0.29900 * R + 0.58700 * G + 0.11400 * B));

  Cb := ClampToWord(Round(-0.16874 * R - 0.33126 * G + 0.50000 * B  + 32768));

  Cr := ClampToWord(Round( 0.50000 * R - 0.41869 * G - 0.08131 * B  + 32768));

end;

procedure YCbCrToRGB16(Y, Cb, Cr: Word; var R, G, B: Word);

begin

  R := ClampToWord(Round(Y                          + 1.40200 * (Cr - 32768)));

  G := ClampToWord(Round(Y - 0.34414 * (Cb - 32768) - 0.71414 * (Cr - 32768)));

  B := ClampToWord(Round(Y + 1.77200 * (Cb - 32768)));

end;

procedure RGBToCMY(R, G, B: Byte; var C, M, Y: Byte);

begin

  C := 255 - R;

  M := 255 - G;

  Y := 255 - B;

end;

procedure CMYToRGB(C, M, Y: Byte; var R, G, B: Byte);

begin

  R := 255 - C;

  G := 255 - M;

  B := 255 - Y;

end;

procedure RGBToCMY16(R, G, B: Word; var C, M, Y: Word);

begin

  C := 65535 - R;

  M := 65535 - G;

  Y := 65535 - B;

end;

procedure CMYToRGB16(C, M, Y: Word; var R, G, B: Word);

begin

  R := 65535 - C;

  G := 65535 - M;

  B := 65535 - Y;

end;

procedure RGBToCMYK(R, G, B: Byte; var C, M, Y, K: Byte);

begin

  RGBToCMY(R, G, B, C, M, Y);

  K := Min(C, Min(M, Y));

  if K > 0 then

  begin

    C := C - K;

    M := M - K;

    Y := Y - K;

  end;

end;

procedure CMYKToRGB(C, M, Y, K: Byte; var R, G, B: Byte);

begin

   R := (255 - (C - MulDiv(C, K, 255) + K));

   G := (255 - (M - MulDiv(M, K, 255) + K));

   B := (255 - (Y - MulDiv(Y, K, 255) + K));

end;

procedure RGBToCMYK16(R, G, B: Word; var C, M, Y, K: Word);

begin

  RGBToCMY16(R, G, B, C, M, Y);

  K := Min(C, Min(M, Y));

  if K > 0 then

  begin

    C := C - K;

    M := M - K;

    Y := Y - K;

  end;

end;

procedure CMYKToRGB16(C, M, Y, K: Word; var R, G, B: Word);

begin

  R := 65535 - (C - MulDiv(C, K, 65535) + K);

  G := 65535 - (M - MulDiv(M, K, 65535) + K);

  B := 65535 - (Y - MulDiv(Y, K, 65535) + K);

end;

{

  File Notes:

  -- TODOS ----------------------------------------------------

    - nothing now

  -- 0.23 Changes/Bug Fixes -----------------------------------

    - Added RGB<>CMY(K) converion functions for 16 bit channels

      (needed by PSD loading code).

  -- 0.21 Changes/Bug Fixes -----------------------------------

    - Added some color space conversion functions and LUTs

      (RGB/YUV/YCrCb/CMY/CMYK).

  -- 0.17 Changes/Bug Fixes -----------------------------------

    - unit created (empty!)

}

end.