//---------------------------------------------------------------------------
/*
Secret Message, tool to add secret messages to images
Copyright (C) 2009 Richel Bilderbeek
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
//---------------------------------------------------------------------------
// From http://www.richelbilderbeek.nl
//---------------------------------------------------------------------------
#pragma hdrstop
#include <cassert>
#include <algorithm>
#include "UnitFunctions.h"
//---------------------------------------------------------------------------
//Makes all red pixels even, except when there's a message pixel
//From http://www.richelbilderbeek.nl/CppAddMessageRed.htm
void AddMessageRed(
const TImage * const original,
const TImage * const message,
TImage * const result)
{
assert(original!=0 && "Image is NULL");
assert(message!=0 && "Image is NULL");
assert(result!=0 && "Image is NULL");
assert(original->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(message->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(result->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(original->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
assert(message->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
assert(result->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
//Get sizes and set size
const int widthOriginal = original->Picture->Bitmap->Width;
const int widthMessage = message->Picture->Bitmap->Width;
const int width = std::min(widthOriginal, widthMessage);
result->Picture->Bitmap->Width = width;
const int heightOriginal = original->Picture->Bitmap->Height;
const int heightMessage = message->Picture->Bitmap->Height;
const int height = std::min(heightOriginal, heightMessage);
result->Picture->Bitmap->Height = height;
//Get the pixel offsets
const int dx1 = (widthOriginal - width ) / 2;
const int dx2 = (widthMessage - width ) / 2;
const int dy1 = (heightOriginal - height) / 2;
const int dy2 = (heightMessage - height) / 2;
assert(dx1 >= 0);
assert(dx2 >= 0);
assert(dy1 >= 0);
assert(dy2 >= 0);
for (int y=0; y!=height; ++y)
{
for(int x=0; x!=width; ++x)
{
const int x1 = dx1 + x;
const int x2 = dx2 + x;
const int x3 = x;
assert(x1 >= 0);
assert(x2 >= 0);
assert(x3 >= 0);
assert(x1 < original->Picture->Width);
assert(x2 < message->Picture->Width );
assert(x3 < result->Picture->Width );
const int y1 = dy1 + y;
const int y2 = dy2 + y;
const int y3 = y;
assert(y1 >= 0);
assert(y2 >= 0);
assert(y3 >= 0);
assert(y1 < original->Picture->Height);
assert(y2 < message->Picture->Height);
assert(y3 < result->Picture->Height);
unsigned char r = 0;
unsigned char g = 0;
unsigned char b = 0;
//Get original's pixel
GetPixel(original,x1,y1,r,g,b);
//Make colors even by increment, watch out for 256
if (r%2 != 0)
{
if (r == 255) {--r;}
else { ++r; }
}
assert(r%2 == 0);
assert(r <= 254);
//Add message
const bool isWhite = IsWhite(message,x2,y2);
if (isWhite == true) ++r;
//Write to result image
SetPixel(result,x3,y3,r,g,b);
}
}
}
//---------------------------------------------------------------------------
//From http://www.richelbilderbeek.nl/CppExtractMessageRed.htm
void ExtractMessageRed(
const TImage * const original,
TImage * const result)
{
assert(original!=0 && "Image is NULL");
assert(result!=0 && "Image is NULL");
assert(original->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(result->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(original->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
assert(result->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
//Get sizes and set size
const int width = original->Picture->Bitmap->Width;
result->Picture->Bitmap->Width = width;
const int height = original->Picture->Bitmap->Height;
result->Picture->Bitmap->Height = height;
for (int y=0; y!=height; ++y)
{
for(int x=0; x!=width; ++x)
{
unsigned char r = 0;
unsigned char g = 0;
unsigned char b = 0;
//Get original's pixel
GetPixel(original,x,y,r,g,b);
//Make colors even by increment, watch out for 256
if (r%2 == 0)
{
//No message pixel
SetPixel(result,x,y,0,0,0);
}
else
{
//Message pixel
SetPixel(result,x,y,255,255,255);
}
}
}
}
//---------------------------------------------------------------------------
//Get a pixel's RGB values
//From http://www.richelbilderbeek.nl/CppGetPixel.htm
void GetPixel(
const TImage * const image,
const int x,
const int y,
unsigned char& red,
unsigned char& green,
unsigned char& blue)
{
assert(image!=0 && "Image is NULL");
assert(image->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(image->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
assert( x >= 0 && "x coordinat is below zero");
assert( y >= 0 && "y coordinat is below zero");
assert( x < image->Picture->Bitmap->Width && "x coordinat is beyond image width");
assert( y < image->Picture->Bitmap->Height && "y coordinat is beyond image height");
const unsigned char * const line
= static_cast<unsigned char *>(image->Picture->Bitmap->ScanLine[y]);
red = line[x*3+2];
green = line[x*3+1];
blue = line[x*3+0];
}
//---------------------------------------------------------------------------
//Set a pixel's RGB values
//From http://www.richelbilderbeek.nl/CppSetPixel.htm
void SetPixel(
TImage * const image,
const int x,
const int y,
const unsigned char red,
const unsigned char green,
const unsigned char blue)
{
assert(image!=0 && "Image is NULL");
assert(image->Picture->Bitmap!=0 && "Bitmap is NULL");
assert(image->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");
assert( x >= 0 && "x coordinat is below zero");
assert( y >= 0 && "y coordinat is below zero");
assert( x < image->Picture->Bitmap->Width && "x coordinat is beyond image width");
assert( y < image->Picture->Bitmap->Height && "y coordinat is beyond image height");
unsigned char * const line
= static_cast<unsigned char *>(image->Picture->Bitmap->ScanLine[y]);
line[x*3+2] = red;
line[x*3+1] = green;
line[x*3+0] = blue;
}
//---------------------------------------------------------------------------
const bool IsWhite(const TImage * const image, const int x, const int y)
{
unsigned char r = 0;
unsigned char g = 0;
unsigned char b = 0;
GetPixel(image,x,y,r,g,b);
const int sum = static_cast<int>(r)
+ static_cast<int>(g)
+ static_cast<int>(b);
return (sum / 3 > 127);
}
//---------------------------------------------------------------------------
#pragma package(smart_init)
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