给大家提供几个常用的图象格式转换方法和其转换函数
希望可以对你有帮助
1. ICO图标转换BMP格式
2. 32x32 BMP格式图象转换为 ICO格式
3.转换BMP->JPEG文件格式
4.JPEG 转换为BMP函数
5.Bmp转换为JPEG文件格式函数
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1.Chinese : ICO图标转换BMP格式
English :(Conversion from ICO to BMP)
--------------------------------------------------------

  var
    Icon   : TIcon;
    Bitmap : TBitmap;
  begin
     Icon   := TIcon.Create;
     Bitmap := TBitmap.Create;
     Icon.LoadFromFile(''c:\picture.ico'');
     Bitmap.Width := Icon.Width;
     Bitmap.Height := Icon.Height;
     Bitmap.Canvas.Draw(0, 0, Icon );
     Bitmap.SaveToFile(''c:\picture.bmp'');
     Icon.Free;
     Bitmap.Free;
===================================
2.Chinese: 32x32 BMP格式图象转换为 ICO格式
English :32x32 bit Bitmaps to ICO''s
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unit main;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls,
  Forms,Dialogs,ExtCtrls, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    Image2: TImage;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var winDC, srcdc, destdc : HDC;
    oldBitmap : HBitmap;
    iinfo : TICONINFO;
begin
    GetIconInfo(Image1.Picture.Icon.Handle, iinfo);

    WinDC := getDC(handle);
    srcDC := CreateCompatibleDC(WinDC);
    destDC := CreateCompatibleDC(WinDC);
    oldBitmap := SelectObject(destDC, iinfo.hbmColor);
    oldBitmap := SelectObject(srcDC, iinfo.hbmMask);

    BitBlt(destdc, 0, 0, Image1.picture.icon.width,
     Image1.picture.icon.height,
           srcdc, 0, 0, SRCPAINT);
    Image2.picture.bitmap.handle := SelectObject(destDC, oldBitmap);
    DeleteDC(destDC);
    DeleteDC(srcDC);
    DeleteDC(WinDC);

image2.Picture.Bitmap.savetofile(ExtractFilePath(Application.ExeName)
          + ''myfile.bmp