Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/Drawing.php
public static function imagecreatefrombmp($p_sFile)
    {
        //    Load the image into a string
        $file = fopen($p_sFile, 'rb');
        $read = fread($file, 10);
        while (!feof($file) && ($read != '')) {
            $read .= fread($file, 1024);
        }

        $temp = unpack('H*', $read);
        $hex = $temp[1];
        $header = substr($hex, 0, 108);

        //    Process the header
        //    Structure: http://www.fastgraph.com/help/bmp_header_format.html
        if (substr($header, 0, 4) == '424d') {
            //    Cut it in parts of 2 bytes
            $header_parts = str_split($header, 2);

            //    Get the width        4 bytes
            $width = hexdec($header_parts[19] . $header_parts[18]);

            //    Get the height        4 bytes
            $height = hexdec($header_parts[23] . $header_parts[22]);

            //    Unset the header params
            unset($header_parts);
        }

        //    Define starting X and Y
        $x = 0;
        $y = 1;

        //    Create newimage
        $image = imagecreatetruecolor($width, $height);

        //    Grab the body from the image
        $body = substr($hex, 108);

        //    Calculate if padding at the end-line is needed
        //    Divided by two to keep overview.
        //    1 byte = 2 HEX-chars
        $body_size = (strlen($body) / 2);
        $header_size = ($width * $height);

        //    Use end-line padding? Only when needed
        $usePadding = ($body_size > ($header_size * 3) + 4);

        //    Using a for-loop with index-calculation instaid of str_split to avoid large memory consumption
        //    Calculate the next DWORD-position in the body
        for ($i = 0; $i < $body_size; $i += 3) {
            //    Calculate line-ending and padding
            if ($x >= $width) {
                // If padding needed, ignore image-padding
                // Shift i to the ending of the current 32-bit-block
                if ($usePadding) {
                    $i += $width % 4;
                }

                //    Reset horizontal position
                $x = 0;

                //    Raise the height-position (bottom-up)
                ++$y;

                //    Reached the image-height? Break the for-loop
                if ($y > $height) {
                    break;
                }
            }

            // Calculation of the RGB-pixel (defined as BGR in image-data)
            // Define $i_pos as absolute position in the body
            $i_pos = $i * 2;
            $r = hexdec($body[$i_pos + 4] . $body[$i_pos + 5]);
            $g = hexdec($body[$i_pos + 2] . $body[$i_pos + 3]);
            $b = hexdec($body[$i_pos] . $body[$i_pos + 1]);

            // Calculate and draw the pixel
            $color = imagecolorallocate($image, $r, $g, $b);
            imagesetpixel($image, $x, $height - $y, $color);

            // Raise the horizontal position
            ++$x;
        }

        // Unset the body / free the memory
        unset($body);

        //    Return image-object
        return $image;
    }
public static function imagecreatefrombmp($p_sFile)
    {
        //    Load the image into a string
        $file = fopen($p_sFile, 'rb');
        $read = fread($file, 10);
        while (!feof($file) && ($read != '')) {
            $read .= fread($file, 1024);
        }

        $temp = unpack('H*', $read);
        $hex = $temp[1];
        $header = substr($hex, 0, 108);

        //    Process the header
        //    Structure: http://www.fastgraph.com/help/bmp_header_format.html
        if (substr($header, 0, 4) == '424d') {
            //    Cut it in parts of 2 bytes
            $header_parts = str_split($header, 2);

            //    Get the width        4 bytes
            $width = hexdec($header_parts[19] . $header_parts[18]);

            //    Get the height        4 bytes
            $height = hexdec($header_parts[23] . $header_parts[22]);

            //    Unset the header params
            unset($header_parts);
        }

        //    Define starting X and Y
        $x = 0;
        $y = 1;

        //    Create newimage
        $image = imagecreatetruecolor($width, $height);

        //    Grab the body from the image
        $body = substr($hex, 108);

        //    Calculate if padding at the end-line is needed
        //    Divided by two to keep overview.
        //    1 byte = 2 HEX-chars
        $body_size = (strlen($body) / 2);
        $header_size = ($width * $height);

        //    Use end-line padding? Only when needed
        $usePadding = ($body_size > ($header_size * 3) + 4);

        //    Using a for-loop with index-calculation instaid of str_split to avoid large memory consumption
        //    Calculate the next DWORD-position in the body
        for ($i = 0; $i < $body_size; $i += 3) {
            //    Calculate line-ending and padding
            if ($x >= $width) {
                // If padding needed, ignore image-padding
                // Shift i to the ending of the current 32-bit-block
                if ($usePadding) {
                    $i += $width % 4;
                }

                //    Reset horizontal position
                $x = 0;

                //    Raise the height-position (bottom-up)
                ++$y;

                //    Reached the image-height? Break the for-loop
                if ($y > $height) {
                    break;
                }
            }

            // Calculation of the RGB-pixel (defined as BGR in image-data)
            // Define $i_pos as absolute position in the body
            $i_pos = $i * 2;
            $r = hexdec($body[$i_pos + 4] . $body[$i_pos + 5]);
            $g = hexdec($body[$i_pos + 2] . $body[$i_pos + 3]);
            $b = hexdec($body[$i_pos] . $body[$i_pos + 1]);

            // Calculate and draw the pixel
            $color = imagecolorallocate($image, $r, $g, $b);
            imagesetpixel($image, $x, $height - $y, $color);

            // Raise the horizontal position
            ++$x;
        }

        // Unset the body / free the memory
        unset($body);

        //    Return image-object
        return $image;
    }
Create a new image from file. By alexander at alexauto dot nl.

@see http://www.php.net/manual/en/function.imagecreatefromwbmp.php#86214

@param string $p_sFile Path to Windows DIB (BMP) image

@return resource