You can try my function for merging images horizontally or vertically without changing image ratio. just copy paste will work.
function merge($filename_x, $filename_y, $filename_result, $mergeType = 0) {
//$mergeType 0 for horizandal merge 1 for vertical merge
// Get dimensions for specified images
list($width_x, $height_x) = getimagesize($filename_x);
list($width_y, $height_y) = getimagesize($filename_y);
$lowerFileName = strtolower($filename_x);
if(substr_count($lowerFileName, '.jpg')>0 || substr_count($lowerFileName, '.jpeg')>0){
$image_x = imagecreatefromjpeg($filename_x);
}else if(substr_count($lowerFileName, '.png')>0){
$image_x = imagecreatefrompng($filename_x);
}else if(substr_count($lowerFileName, '.gif')>0){
$image_x = imagecreatefromgif($filename_x);
}
$lowerFileName = strtolower($filename_y);
if(substr_count($lowerFileName, '.jpg')>0 || substr_count($lowerFileName, '.jpeg')>0){
$image_y = imagecreatefromjpeg($filename_y);
}else if(substr_count($lowerFileName, '.png')>0){
$image_y = imagecreatefrompng($filename_y);
}else if(substr_count($lowerFileName, '.gif')>0){
$image_y = imagecreatefromgif($filename_y);
}
if($mergeType==0){
//for horizandal merge
if($height_y<$height_x){
$new_height = $height_y;
$new_x_height = $new_height;
$precentageReduced = ($height_x - $new_height)/($height_x/100);
$new_x_width = ceil($width_x - (($width_x/100) * $precentageReduced));
$tmp = imagecreatetruecolor($new_x_width, $new_x_height);
imagecopyresampled($tmp, $image_x, 0, 0, 0, 0, $new_x_width, $new_x_height, $width_x, $height_x);
$image_x = $tmp;
$height_x = $new_x_height;
$width_x = $new_x_width;
}else{
$new_height = $height_x;
$new_y_height = $new_height;
$precentageReduced = ($height_y - $new_height)/($height_y/100);
$new_y_width = ceil($width_y - (($width_y/100) * $precentageReduced));
$tmp = imagecreatetruecolor($new_y_width, $new_y_height);
imagecopyresampled($tmp, $image_y, 0, 0, 0, 0, $new_y_width, $new_y_height, $width_y, $height_y);
$image_y = $tmp;
$height_y = $new_y_height;
$width_y = $new_y_width;
}
$new_width = $width_x + $width_y;
$image = imagecreatetruecolor($new_width, $new_height);
imagecopy($image, $image_x, 0, 0, 0, 0, $width_x, $height_x);
imagecopy($image, $image_y, $width_x, 0, 0, 0, $width_y, $height_y);
}else{
//for verical merge
if($width_y<$width_x){
$new_width = $width_y;
$new_x_width = $new_width;
$precentageReduced = ($width_x - $new_width)/($width_x/100);
$new_x_height = ceil($height_x - (($height_x/100) * $precentageReduced));
$tmp = imagecreatetruecolor($new_x_width, $new_x_height);
imagecopyresampled($tmp, $image_x, 0, 0, 0, 0, $new_x_width, $new_x_height, $width_x, $height_x);
$image_x = $tmp;
$width_x = $new_x_width;
$height_x = $new_x_height;
}else{
$new_width = $width_x;
$new_y_width = $new_width;
$precentageReduced = ($width_y - $new_width)/($width_y/100);
$new_y_height = ceil($height_y - (($height_y/100) * $precentageReduced));
$tmp = imagecreatetruecolor($new_y_width, $new_y_height);
imagecopyresampled($tmp, $image_y, 0, 0, 0, 0, $new_y_width, $new_y_height, $width_y, $height_y);
$image_y = $tmp;
$width_y = $new_y_width;
$height_y = $new_y_height;
}
$new_height = $height_x + $height_y;
$image = imagecreatetruecolor($new_width, $new_height);
imagecopy($image, $image_x, 0, 0, 0, 0, $width_x, $height_x);
imagecopy($image, $image_y, 0, $height_x, 0, 0, $width_y, $height_y);
}
$lowerFileName = strtolower($filename_result);
if(substr_count($lowerFileName, '.jpg')>0 || substr_count($lowerFileName, '.jpeg')>0){
imagejpeg($image, $filename_result);
}else if(substr_count($lowerFileName, '.png')>0){
imagepng($image, $filename_result);
}else if(substr_count($lowerFileName, '.gif')>0){
imagegif($image, $filename_result);
}
// Clean up
imagedestroy($image);
imagedestroy($image_x);
imagedestroy($image_y);
}
merge('images/h_large.jpg', 'images/v_large.jpg', 'images/merged_har.jpg',0); //merge horizontally
merge('images/h_large.jpg', 'images/v_large.jpg', 'images/merged.jpg',1); //merge vertically