___                                    ____  _           _ _            
  |_ _|_ __ ___   __ _  __ _  ___   _ _  / ___|(_)_ __ ___ (_) | __ _ _ __ 
   | || '_ ` _ \ / _` |/ _` |/ _ \ (_|_) \___ \| | '_ ` _ \| | |/ _` | '__|
   | || | | | | | (_| | (_| |  __/  _ _   ___) | | | | | | | | | (_| | |   
  |___|_| |_| |_|\__,_|\__, |\___| (_|_) |____/|_|_| |_| |_|_|_|\__,_|_|   
                       |___/                                               


This is the README for Image::Similar version 0.07.

Image::Similar is a "module" for the Perl computer programming language, a
library of computer code to install on a computer.  This document contains
four sections:

1. About - what the module does

2. Documentation - how to learn more about the module

3. Installation - how to install this module on a computer

4. Help - what to do if you get stuck

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1. ABOUT

Image::Similar - find out how similar two images are

This is an experimental module for comparing images. It uses a
simplified form of the algorithm described in "An image signature
for any kind of image" to calculate image signatures and distances
between images.

The algorithm consists of converting the image into greyscale,
chopping it into a grid, and then computing a signature based on
relative lightness and darkness of the blocks of the grid.

The module does not contain its own image-reading facility, so images
must be loaded to the module via one of the following supported Perl
modules:

"Imager" (recommended)

All image types are supported. If you have no preference, I suggest
using Imager, since it is a very well-behaved module. The conversion
to greyscale is done using Imager's own routines.

"GD"

All image types are supported. RGB images are combined to greyscale
using constants taken from the source code of "Imager".

"Image::Imlib2"

All image types are supported. RGB images are combined to greyscale
using constants taken from the source code of "Imager".

"Image::PNG::Libpng"

This module is used for some internals of Image::Similar related to
testing, thus it was installed when you installed
Image::Similar. However, Image::PNG::Libpng is only for PNG images.

Image::Similar supports all PNG image types. It currently only
supports bit depths of eight.

RGB images are combined to greyscale using constants taken from the
source code of "Imager". As of this version, there is no handling of
the alpha channel (transparent pixels) and the background value is
ignored.

Use "load_image" to load the image.

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2. DOCUMENTATION

You can read the documentation for the module online at the following
websites:

    * http://search.cpan.org/perldoc?Image::Similar
    * http://metacpan.org/release/Image-Similar

(These links go to the latest version of the module.)

After installing the module, you can read the documentation on your
computer using

    perldoc Image::Similar

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3. INSTALLATION

This module requires Perl version 5.6.1 or later.

To install the module from CPAN, use

    cpan Image::Similar

If you have the App::cpanminus installer, you may prefer

    cpanm Image::Similar

To install the module from the source file, Image-Similar-0.07.tar.gz,
follow this sequence of commands:

    tar xfz Image-Similar-0.07.tar.gz
    cd Image-Similar-0.07
    perl Makefile.PL
    make
    make install

If you want to test the module before installing it, use "make test" after
"make" and before "make install".

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4. HELP

To get help with the module, you can email the author, Ben Bullock, at
<bkb@cpan.org>. If you think there is a problem in the module, you can
report a bug at 

<https://github.com/benkasminbullock/image-similar/issues>,

or if you want to alter the source code of Image::Similar, try the public
repository on github at 

<https://github.com/benkasminbullock/image-similar>. 

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This README was written on Sat Jul 15 16:00:52 2017.

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