Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xls/Color.php
public static function map($color, $palette, $version)
    {
        if ($color <= 0x07 || $color >= 0x40) {
            // special built-in color
            return Color\BuiltIn::lookup($color);
        } elseif (isset($palette, $palette[$color - 8])) {
            // palette color, color index 0x08 maps to pallete index 0
            return $palette[$color - 8];
        }

        // default color table
        if ($version == Xls::XLS_BIFF8) {
            return Color\BIFF8::lookup($color);
        }

        // BIFF5
        return Color\BIFF5::lookup($color);
    }
public static function map($color, $palette, $version)
    {
        if ($color <= 0x07 || $color >= 0x40) {
            // special built-in color
            return Color\BuiltIn::lookup($color);
        } elseif (isset($palette, $palette[$color - 8])) {
            // palette color, color index 0x08 maps to pallete index 0
            return $palette[$color - 8];
        }

        // default color table
        if ($version == Xls::XLS_BIFF8) {
            return Color\BIFF8::lookup($color);
        }

        // BIFF5
        return Color\BIFF5::lookup($color);
    }
Read color.

@param int $color Indexed color
@param array $palette Color palette
@param int $version

@return array RGB color value, example: ['rgb' => 'FF0000']