Convert 'x-ms-bmp' to 'JPEG/PNG' Image PHP - php

Question

I have a bmp file whose mime type is image/x-ms-bmp. I need to convert this into png or jpeg file. I have done below code :
$imagecreatefrombmp = $this->imagecreatefrombmp($imageContent);
ob_start();
imagejpeg($imagecreatefrombmp);
$imagedata = ob_get_contents();
ob_end_clean();
Copied imagecreatefrombmp as below :
public function imagecreatefrombmp($readContent)
{
/* // Load the image into a string
$file = fopen($p_sFile,"rb");
$read = fread($file,10);
while(!feof($file)&&($read<>""))
$read .= fread($file,1024); */
$temp = unpack("H*",$readContent);
$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;
}
Its not creating the image correctly.
I need to render this image in a RTF file.