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Png(3)		      User Contributed Perl Documentation		Png(3)

NAME
       Acme::Steganography::Image::Png - hide data (badly) in Png images

SYNOPSIS
	 use Acme::Steganography::Image::Png;

	 # Write your data out as RGB PNGs hidden in the image "Camouflage.jpg"
	 my $writer = Acme::Steganography::Image::Png::RGB::556FS->new();
	 $writer->data(\$data);
	 my @filenames = $writer->write_images("Camouflage.jpg");
	 # Returns a list of the filenames it wrote to

	 # Then	read them back.
	 my $reread =
	    Acme::Steganography::Image::Png::RGB::556->read_files(@files);

DESCRIPTION
       Acme::Steganography::Image::Png is extremely ineffective	at hiding your
       secrets inside Png images.

       There are 4 implementations

       Acme::Steganography::Image::Png::FlashingNeonSignGrey
	   Blatantly stuffs your data into greyscale PNG files with absolutely
	   no attempt to hide it.

       Acme::Steganography::Image::Png::RGB::556
	   Stuffs your data into a sample image, using the low order bits of
	   each	colour.	 2 bytes of your data are stored in each pixel,	5 bits
	   in Red and Green, 6 in Blue.	It produces a rather grainy image.

       Acme::Steganography::Image::Png::RGB::323
	   Also	stuffs your data into a	sample image, using the	low order bits
	   of each colour. Only	1 byte of your data is stored in each pixel, 3
	   bits	in Red and Blue, 2 in Green. To	the untrained eye the image
	   looks good. But the fact that it's PNG will make anyone suspicious
	   about the contents.

       Acme::Steganography::Image::Png::RGB::556FS
	   Stuffs your data into a sample image, using the low order bits of
	   each	colour.	 2 bytes of your data are stored in each pixel,	5 bits
	   in Red and Green, 6 in Blue.	Changing the value of pixels to	store
	   data	is adding error	to the image, in this case rather a lot	of
	   error. To attempt to	conceal	some of	the graininess Floyd-Steinberg
	   dithering is	used to	spread the errors around. It's not perfect,
	   but effects are quite interesting, producing	a reasonably nice
	   dithered image.

       Write your data out by calling "write_images"

       Read your data back in by calling "read_files"

       You don't have to return	the filenames in the correct order.

BUGS
       Virtually no documentation. There's the source code...

       Not very	many tests.

       Not robust against missing files	when re-reading

       If you want real	steganography, you're in the wrong place.

       Doesn't really do enough	daft stuff yet to live up to being a proper
       Acme module. There are plans.

AUTHOR
       Nicholas	Clark, <nick@ccl4.org>,	based on code written by JCHIN after a
       conversation we had.

perl v5.32.1			  2006-10-01				Png(3)

NAME | SYNOPSIS | DESCRIPTION | BUGS | AUTHOR

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