src/Intervention/Gif/Decoded.php
public function getBackgroundColorIndex()
    {
        if ($this->logicalScreenDescriptor) {
            $index = substr($this->logicalScreenDescriptor, 5, 1);
            $index = unpack('C', $index)[1];

            return $index;
        }

        return 0;
    }
public function getBackgroundColorIndex()
    {
        if ($this->logicalScreenDescriptor) {
            $index = substr($this->logicalScreenDescriptor, 5, 1);
            $index = unpack('C', $index)[1];

            return $index;
        }

        return 0;
    }
Returns background color index

@return integer