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DEFINITIONS
This source file includes following definitions.
- MagickMin
- ReadSTEGANOImage
- RegisterSTEGANOImage
- UnregisterSTEGANOImage
/*
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% Write A Steganographic Image. %
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% Software Design %
% John Cristy %
% July 1992 %
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% Copyright 1999-2013 ImageMagick Studio LLC, a non-profit organization %
% dedicated to making software imaging solutions freely available. %
% %
% You may not use this file except in compliance with the License. You may %
% obtain a copy of the License at %
% %
% http://www.imagemagick.org/script/license.php %
% %
% Unless required by applicable law or agreed to in writing, software %
% distributed under the License is distributed on an "AS IS" BASIS, %
% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. %
% See the License for the specific language governing permissions and %
% limitations under the License. %
% %
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*/
/*
Include declarations.
*/
#include "magick/studio.h"
#include "magick/blob.h"
#include "magick/blob-private.h"
#include "magick/cache.h"
#include "magick/colormap.h"
#include "magick/constitute.h"
#include "magick/exception.h"
#include "magick/exception-private.h"
#include "magick/image.h"
#include "magick/image-private.h"
#include "magick/list.h"
#include "magick/magick.h"
#include "magick/memory_.h"
#include "magick/monitor.h"
#include "magick/monitor-private.h"
#include "magick/pixel-accessor.h"
#include "magick/quantum-private.h"
#include "magick/static.h"
#include "magick/string_.h"
#include "magick/module.h"
/*
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% R e a d S T E G A N O I m a g e %
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% ReadSTEGANOImage() reads a steganographic image hidden within another
% image type. It allocates the memory necessary for the new Image structure
% and returns a pointer to the new image.
%
% The format of the ReadSTEGANOImage method is:
%
% Image *ReadSTEGANOImage(const ImageInfo *image_info,
% ExceptionInfo *exception)
%
% A description of each parameter follows:
%
% o image_info: the image info.
%
% o exception: return any errors or warnings in this structure.
%
*/
static inline size_t MagickMin(const size_t x,
const size_t y)
{
if (x < y)
return(x);
return(y);
}
static Image *ReadSTEGANOImage(const ImageInfo *image_info,
ExceptionInfo *exception)
{
#define GetBit(alpha,i) MagickMin((((size_t) (alpha) >> (size_t) \
(i)) & 0x01),16)
#define SetBit(indexes,i,set) SetPixelIndex(indexes,((set) != 0 ? \
(size_t) GetPixelIndex(indexes) | (one << (size_t) (i)) : (size_t) \
GetPixelIndex(indexes) & ~(one << (size_t) (i))))
Image
*image,
*watermark;
ImageInfo
*read_info;
int
c;
MagickBooleanType
status;
PixelPacket
pixel;
register IndexPacket
*indexes;
register PixelPacket
*q;
register ssize_t
x;
size_t
depth,
one;
ssize_t
i,
j,
k,
y;
/*
Initialize Image structure.
*/
assert(image_info != (const ImageInfo *) NULL);
assert(image_info->signature == MagickSignature);
if (image_info->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
image_info->filename);
assert(exception != (ExceptionInfo *) NULL);
assert(exception->signature == MagickSignature);
one=1;
image=AcquireImage(image_info);
if ((image->columns == 0) || (image->rows == 0))
ThrowReaderException(OptionError,"MustSpecifyImageSize");
read_info=CloneImageInfo(image_info);
SetImageInfoBlob(read_info,(void *) NULL,0);
*read_info->magick='\0';
watermark=ReadImage(read_info,exception);
read_info=DestroyImageInfo(read_info);
if (watermark == (Image *) NULL)
return((Image *) NULL);
watermark->depth=MAGICKCORE_QUANTUM_DEPTH;
if (AcquireImageColormap(image,MaxColormapSize) == MagickFalse)
ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
if (image_info->ping != MagickFalse)
{
(void) CloseBlob(image);
return(GetFirstImageInList(image));
}
/*
Get hidden watermark from low-order bits of image.
*/
c=0;
i=0;
j=0;
i=(ssize_t) (watermark->depth-1);
depth=watermark->depth;
for (k=image->offset; (i >= 0) && (j < (ssize_t) depth); i--)
{
for (y=0; (y < (ssize_t) image->rows) && (j < (ssize_t) depth); y++)
{
x=0;
for ( ; (x < (ssize_t) image->columns) && (j < (ssize_t) depth); x++)
{
if ((k/(ssize_t) watermark->columns) >= (ssize_t) watermark->rows)
break;
(void) GetOneVirtualPixel(watermark,k % (ssize_t) watermark->columns,
k/(ssize_t) watermark->columns,&pixel,exception);
q=GetAuthenticPixels(image,x,y,1,1,exception);
if (q == (PixelPacket *) NULL)
break;
indexes=GetAuthenticIndexQueue(image);
switch (c)
{
case 0:
{
SetBit(indexes,i,GetBit(pixel.red,j));
break;
}
case 1:
{
SetBit(indexes,i,GetBit(pixel.green,j));
break;
}
case 2:
{
SetBit(indexes,i,GetBit(pixel.blue,j));
break;
}
}
if (SyncAuthenticPixels(image,exception) == MagickFalse)
break;
c++;
if (c == 3)
c=0;
k++;
if (k == (ssize_t) (watermark->columns*watermark->columns))
k=0;
if (k == image->offset)
j++;
}
}
status=SetImageProgress(image,LoadImagesTag,(MagickOffsetType) i,depth);
if (status == MagickFalse)
break;
}
watermark=DestroyImage(watermark);
(void) SyncImage(image);
return(GetFirstImageInList(image));
}
/*
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% R e g i s t e r S T E G A N O I m a g e %
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% RegisterSTEGANOImage() adds attributes for the STEGANO image format to
% the list of supported formats. The attributes include the image format
% tag, a method to read and/or write the format, whether the format
% supports the saving of more than one frame to the same file or blob,
% whether the format supports native in-memory I/O, and a brief
% description of the format.
%
% The format of the RegisterSTEGANOImage method is:
%
% size_t RegisterSTEGANOImage(void)
%
*/
ModuleExport size_t RegisterSTEGANOImage(void)
{
MagickInfo
*entry;
entry=SetMagickInfo("STEGANO");
entry->decoder=(DecodeImageHandler *) ReadSTEGANOImage;
entry->format_type=ImplicitFormatType;
entry->description=ConstantString("Steganographic image");
entry->module=ConstantString("STEGANO");
(void) RegisterMagickInfo(entry);
return(MagickImageCoderSignature);
}
/*
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% U n r e g i s t e r S T E G A N O I m a g e %
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% UnregisterSTEGANOImage() removes format registrations made by the
% STEGANO module from the list of supported formats.
%
% The format of the UnregisterSTEGANOImage method is:
%
% UnregisterSTEGANOImage(void)
%
*/
ModuleExport void UnregisterSTEGANOImage(void)
{
(void) UnregisterMagickInfo("STEGANO");
}