The following functions RGBTOCMYK() and CMYKTORGB() demonstrate how to convert between RGB and CMYK color spaces. Note: There is a direct relationship between RGB colors and CMY colors. In a CMY color, black tones are achieved by printing equal amounts of Cyan, Magenta, and Yellow ink. The black component in a CMY color is achieved by reducing the CMY components by the minimum of (C, M, and Y) and substituting pure black in its place producing a sharper print and using less ink. Since it is possible for a user to boost the C,M and Y components where boosting the black component would have been preferable, a ColorCorrectCMYK() function is provided to achieve the same color by reducing the C, M and Y components, and boosting the K component. Example:

procedure RGBTOCMYK(R : byte; G : byte; B : byte; var C : byte; var M : byte; var Y : byte; var K : byte); begin C := 255 - R; M := 255 - G; Y := 255 - B; if C < M then K := C else K := M; if Y < K then K := Y; if k > 0 then begin c := c - k; m := m - k; y := y - k; end; end;

procedure CMYKTORGB(C : byte; M: byte; Y : byte; K : byte; var R : byte; var G : byte; var B : byte); begin if (Integer(C) + Integer(K)) < 255 then R := 255 - (C + K) else R := 0; if (Integer(M) + Integer(K)) < 255 then G := 255 - (M + K) else G := 0; if (Integer(Y) + Integer(K)) < 255 then B := 255 - (Y + K) else B := 0; end;

procedure ColorCorrectCMYK(var C : byte; var M : byte; var Y : byte; var K : byte); var MinColor : byte; begin if C < M then MinColor := C else MinColor := M; if Y < MinColor then MinColor := Y; if MinColor + K > 255 then MinColor := 255 - K; C := C - MinColor; M := M - MinColor; Y := Y - MinColor; K := K + MinColor; end;

procedure TForm .Button Click(Sender: TObject); var R : byte; G : byte; B : byte; C : byte; M : byte; Y : byte; K : byte; begin R := 5 ; G := 8 ; B := 55; Memo .Lines.Add('R = ' + IntToStr(R)); Memo .Lines.Add('G = ' + IntToStr(G)); Memo .Lines.Add('B = ' + IntToStr(B)); Memo .Lines.Add('-------------------'); RGBTOCMYK(R, G, B, C, M, Y, K); Memo .Lines.Add('C = ' + IntToStr(C)); Memo .Lines.Add('M = ' + IntToStr(M)); Memo .Lines.Add('Y = ' + IntToStr(Y)); Memo .Lines.Add('K = ' + IntToStr(K)); Memo .Lines.Add('-------------------'); CMYKTORGB(C, M, Y, K, R, G, B); Memo .Lines.Add('R = ' + IntToStr(R)); Memo .Lines.Add('G = ' + IntToStr(G)); Memo .Lines.Add('B = ' + IntToStr(B)); Memo .Lines.Add('-------------------'); RGBTOCMYK(R, G, B, C, M, Y, K); c := c + 2; m := m + 2; y := y + 2; ColorCorrectCMYK(C, M, Y, K); Memo .Lines.Add('C = ' + IntToStr(C)); Memo .Lines.Add('M = ' + IntToStr(M)); Memo .Lines.Add('Y = ' + IntToStr(Y)); Memo .Lines.Add('K = ' + IntToStr(K)); end;

4/2/99 :26: 5 AM