imager::security(3pm) [debian man page]

Imager::Security(3pm)					User Contributed Perl Documentation				     Imager::Security(3pm)

NAME

       Imager::Security - brief notes on security and image processing

SYNOPSIS

	 # keep abreast of security updates
	 apt-get update && apt-get upgrade
	 yum upgrade
	 pkgin update && pkgin upgrade
	 # or local equivalent

	 # limit memory use
	 use Imager;
	 # only images that use up to 10MB
	 Imager->set_file_limits(bytes => 10_000_000);

DESCRIPTION

       There's two basic security considerations when dealing with images from an unknown source:

       o   keeping your libraries up to date

       o   limiting the amount of memory used to store images

   Keeping libraries up to date
       Image file format libraries such as "libpng" or "libtiff" have relatively frequent security updates, keeping your libraries up to date is
       basic security.

       If you're using user supplied fonts, you will need to keep your font libraries up to date too.

   Limiting memory used
       With compression, and especially with pointer formats like TIFF, it's possible to store very large images in a relatively small file.

       If you're receiving image data from an untrusted source you should limit the amount of memory that Imager can allocate for a read in image
       file using the "set_file_limits()" method.

	 Imager->set_file_limits(bytes => 10_000_000);

       You may also want to limit the maximum width and height of images read from files:

	 Imager->set_file_limits(width => 10_000, height => 10_000,
				 bytes => 10_000_000);

       This has no effect on images created without a file:

	 # succeeds
	 my $image = Imager->new(xsize => 10_001, ysize => 10_001);

       You can reset to the defaults with:

	 Imager->set_file_limits(reset => 1);

AUTHOR

       Tony Cook <tonyc@cpan.org>

perl v5.14.2							    2012-06-04						     Imager::Security(3pm)

Imager::Color::Float(3pm)				User Contributed Perl Documentation				 Imager::Color::Float(3pm)

NAME

       Imager::Color::Float - Rough floating point sample color handling

SYNOPSIS

	 $color = Imager::Color->new($red, $green, $blue);
	 $color = Imager::Color->new($red, $green, $blue, $alpha);
	 $color = Imager::Color->new("#C0C0FF"); # html color specification

	 $color->set($red, $green, $blue);
	 $color->set($red, $green, $blue, $alpha);
	 $color->set("#C0C0FF"); # html color specification

	 ($red, $green, $blue, $alpha) = $color->rgba();
	 @hsv = $color->hsv(); # not implemented but proposed

	 $color->info();

DESCRIPTION

       This module handles creating color objects used by Imager.  The idea is that in the future this module will be able to handle color space
       calculations as well.

       A floating point Imager color consists of up to four components, each in the range 0.0 to 1.0. Unfortunately the meaning of the components
       can change depending on the type of image you're dealing with:

       o   for 3 or 4 channel images the color components are red, green, blue, alpha.

       o   for 1 or 2 channel images the color components are gray, alpha, with the other two components ignored.

       An alpha value of zero is fully transparent, an alpha value of 1.0 is fully opaque.

METHODS

       new This creates a color object to pass to functions that need a color argument.

       set This changes an already defined color.  Note that this does not affect any places where the color has been used previously.

       rgba()
	   This returns the red, green, blue and alpha channels of the color the object contains.

       info
	   Calling info merely dumps the relevant color to the log.

AUTHOR

       Arnar M. Hrafnkelsson, addi@umich.edu And a great deal of help from others - see the "README" for a complete list.

SEE ALSO

       Imager(3), Imager::Color.

       http://imager.perl.org/

perl v5.14.2							    2011-06-06						 Imager::Color::Float(3pm)