%Image::ExifTool::UserDefined = (
    'Image::ExifTool::PNG::Main' => {
        PLTE => {
            Name => 'Palette',
            ValueConv => q{
                my $str = '[' . join(', ', unpack('C*',$val)) . ']';
                $str =~ s/(\d+, \d+, \d+)/($1)/g;
                return $str;
            },
        },
    },
    'Image::ExifTool::Composite' => {
        PNGTransparency => {
            Require => {
                0 => 'PNG:Transparency',
                1 => 'PNG:ColorType',
            },
            ValueConv => q{
                my @transparencyData = unpack('C*', $val[0]);
                if ($val[1] == 3) { # Indexed-color/palette
                    return '[' . join(',', @transparencyData) . ']';
                } elsif ($val[1] == 0) { # Grayscale
                    # Unpack as a single 2-byte value
                    my ($transparency) = unpack('n', $val[0]);
                    return $transparency;
                } elsif ($val[1] == 2) { # RGB
                    # Unpack the first three 2-byte values from transparency data
                    my @rgbaTransparency = unpack('n3', $val[0]);
                    return '[' . join(',', @rgbaTransparency) . ']';
                }
                return '';
            },
        },
    },
);

1;