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How to force a black and white printou of a color image

edited December 2002 in Devices
Hi...

I?m having some trouble with printing a wmf image that I need to be
interpreted as Black and white, no matter on what printer it is sent to.

Is there a way to accomplish this with RB?

Thanks,

Eduardo Gomes
Insurance Solutions

Comments

  • edited December 2002
    One choice would be to convert it to grayscale yourself before printing it.

    You could use or start from one of these convert fonctions :

    function ConvertBitmapToGrayscale1(const Bitmap: TBitmap): TBitmap;
    var
    i, j: Integer;
    Grayshade, Red, Green, Blue: Byte;
    PixelColor: Longint;
    begin
    with Bitmap do
    for i := 0 to Width - 1 do
    for j := 0 to Height - 1 do
    begin
    PixelColor := ColorToRGB(Canvas.Pixels[i, j]);
    Red := PixelColor;
    Green := PixelColor shr 8;
    Blue := PixelColor shr 16;
    Grayshade := Round(0.3 * Red + 0.6 * Green + 0.1 * Blue);
    Canvas.Pixels[i, j] := RGB(Grayshade, Grayshade, Grayshade);
    end;
    Result := Bitmap;
    end;



    procedure ConvertBitmapToGrayscale2(const Bmp: TBitmap);
    {From: Pascal Enz, pascal.enz@datacomm.ch }
    type
    TRGBArray = array[0..32767] of TRGBTriple;
    PRGBArray = ^TRGBArray;
    var
    x, y, Gray: Integer;
    Row: PRGBArray;
    begin
    Bmp.PixelFormat := pf24Bit;
    for y := 0 to Bmp.Height - 1 do
    begin
    Row := Bmp.ScanLine[y];
    for x := 0 to Bmp.Width - 1 do
    begin
    Gray := (Row[x].rgbtRed + Row[x].rgbtGreen +
    Row[x].rgbtBlue) div 3;
    Row[x].rgbtRed := Gray;
    Row[x].rgbtGreen := Gray;
    Row[x].rgbtBlue := Gray;
    end;
    end;
    end;


    procedure ConvertBitmapToGrayscale3(const Bitmap: TBitmap);
    type
    PPixelRec = ^TPixelRec;
    TPixelRec = packed record
    B: Byte;
    G: Byte;
    R: Byte;
    Reserved: Byte;
    end;
    var
    X: Integer;
    Y: Integer;
    P: PPixelRec;
    Gray: Byte;
    begin
    Assert(Bitmap.PixelFormat = pf32Bit);
    for Y := 0 to (Bitmap.Height - 1) do
    begin
    P := Bitmap.ScanLine[Y];
    for X := 0 to (Bitmap.Width - 1) do
    begin
    Gray := Round(0.30 * P.R + 0.59 * P.G + 0.11 * P.B);
    // Gray := (P.R shr 2) + (P.R shr 4) + (P.G shr 1) + (P.G shr 4) +
    (P.B shr 3);
    P.R := Gray;
    P.G := Gray;
    P.B := Gray;
    Inc(P);
    end;
    end;
    end;


    --
    Daniel Lemire
  • edited December 2002
    Thanks,

    Gonna try it out...

    Eduardo Gomes
    Insurance Solutions

This discussion has been closed.