classes/handlers/magick.php
public function contrast( $value, $region = null )
    {
        if ( $value < - 100 || $value > 100 )
        {
            throw new ezcBaseValueException( 'value', $value, 'int >= -100 && int <= 100' );
        }

        $round_value = round( $value / 10 );

        if ( $round_value >= 0 )
        {
            $option = '-contrast';
        }
        else
        {
            $option = '+contrast';
            $round_value = - $round_value;
        }

        $this->setRegion( $region );
        for ( $i = 0; $i < $round_value; ++$i )
        {
            $this->addFilterOption(
                $this->getActiveReference(),
                $option
            );
        }
    }
public function contrast( $value, $region = null )
    {
        if ( $value < - 100 || $value > 100 )
        {
            throw new ezcBaseValueException( 'value', $value, 'int >= -100 && int <= 100' );
        }

        $round_value = round( $value / 10 );

        if ( $round_value >= 0 )
        {
            $option = '-contrast';
        }
        else
        {
            $option = '+contrast';
            $round_value = - $round_value;
        }

        $this->setRegion( $region );
        for ( $i = 0; $i < $round_value; ++$i )
        {
            $this->addFilterOption(
                $this->getActiveReference(),
                $option
            );
        }
    }
/* (non-PHPdoc)
@see extension/ezie/autoloads/eziezc/interfaces/eZIEEzcConversions#contrast($value)