Jpeg Brightness

unit Unit3;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, ComCtrls, StdCtrls,jpeg;

type
TForm3 = class(TForm)
ScrollBox1: TScrollBox;
ScrollBox2: TScrollBox;
TrackBar1: TTrackBar;
OrigImage: TImage;
DestImage: TImage;
ValueLbl: TLabel;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
procedure FormCreate(Sender: TObject);
procedure TrackBar1Change(Sender: TObject);
procedure DestImageDblClick(Sender: TObject);
private
{ Private declarations }

public
{ Public declarations }
end;

var
Form3: TForm3;
const
MaxPixelCount = 32768;

type
pRGBArray = ^TRGBArray;
TRGBArray = ARRAY[0..MaxPixelCount-1] OF TRGBTriple;

function Min(a, b: integer): integer;
function Max(a, b: integer): integer;

implementation

uses Viewer;

{$R *.DFM}

procedure TForm3.FormCreate(Sender: TObject);
var
jpg: TJpegImage;
begin
jpg := TJpegImage.Create;
OrigImage.Picture.Bitmap.PixelFormat := pf24bit;
DestImage.Picture.Bitmap.PixelFormat := pf24bit;
TrackBar1.Position := 0;
ValueLbl.Caption := '0';
end;

procedure TForm3.TrackBar1Change(Sender: TObject);
var i, j, value: integer;
OrigRow, DestRow: pRGBArray;
OrigImage,DestImage:TJPEGImage;//test
begin
// get brightness increment value
value := TTrackBar(Sender).Position;
if value <= 0 then ValueLbl.Caption := IntToStr(value)
else ValueLbl.Caption := Format('+%d', [value]);
// for each row of pixels
for i := 0 to OrigImage.Picture.Height - 1 do
begin
OrigRow := OrigImage.Picture.Bitmap.ScanLine[i];
DestRow := DestImage.Picture.Bitmap.ScanLine[i];
// for each pixel in row
for j := 0 to OrigImage.Picture.Width - 1 do
begin
// add brightness value to pixel's RGB values
if value > 0 then
begin
// RGB values must be less than 256
DestRow[j].rgbtRed := Min(255, OrigRow[j].rgbtRed + value);
DestRow[j].rgbtGreen := Min(255, OrigRow[j].rgbtGreen + value);
DestRow[j].rgbtBlue := Min(255, OrigRow[j].rgbtBlue + value);
end else begin
// RGB values must be greater or equal than 0
DestRow[j].rgbtRed := Max(0, OrigRow[j].rgbtRed + value);
DestRow[j].rgbtGreen := Max(0, OrigRow[j].rgbtGreen + value);
DestRow[j].rgbtBlue := Max(0, OrigRow[j].rgbtBlue + value);
end;
end;
application.ProcessMessages;

DestImage.rePaint;
end;
end;

function Min(a, b: integer): integer;
begin
if a < b then result := a
else result := b;
end;

function Max(a, b: integer): integer;
begin
if a > b then result := a
else result := b;
end;end.