Bitmap Operation for JPEG or JPG Image

Author: admin | Category: Files, Graphic, Tips and Tricks

//This is how we can operate any Bitmap Operation to our JPEG image
//To make a bitmap operation in JPEG Image, first we need to convert JPEG Image to bitmap
//Then run any bitmap operation on convert result bitmap
//Then assign JPEG result from operated bitmap
//For this example we use convert to grayscale bitmap operation
//Use Button1(TButton) and OpenDialog1(TOpenDialog) for this example
 
unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    OpenDialog1: TOpenDialog;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
uses
  jpeg;
 
{$R *.dfm}
 
function ConvertBitmapToGrayscale(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 ConvertToBitmap(Source : TGraphic; Bitmap : TBitmap);
begin
 try
  if Bitmap = nil then
    Bitmap := TBitmap.Create
  else Bitmap.FreeImage;
  Bitmap.Width := Source.Width;
  Bitmap.Height := Source.Height;
  Bitmap.Canvas.Draw(0,0,Source);
 except
   showmessage('No Loaded File');
 end;
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
  MyJpeg,OperatedJpeg:TJPEGImage;
  MyBitmap,OperatedBitmap:TBitmap;
begin
  if OpenDialog1.Execute then
  begin
    MyJpeg        := TJPEGImage.Create;
    MyBitmap      := TBitmap.Create;
    OperatedBitmap := TBitmap.Create;
    OperatedJpeg   :=  TJPEGImage.Create;
    try
      MyJpeg.LoadFromFile(OpenDialog1.FileName);
      ConvertToBitmap(MyJpeg,MyBitmap);
      // Do any Bitmap Operation Here
      //For Example i Convert Bitmap To GrayScale and perform result into
      //operateBitmap
      OperatedBitmap := ConvertBitmapToGrayscale(MyBitmap);
      //Perform operated bitmap into jpeg
      OperatedJpeg.Assign(OperatedBitmap);
      OperatedJpeg.SaveToFile(OpenDialog1.FileName+'-Gray.jpeg');
      Showmessage('Operation Completed')
    finally
      MyJpeg.Free;
      OperatedJpeg.Free;
    end;
  end;
end;
 
end.

Tags: Bitmap, Graphic, Image, JPEG, JPG