Black result image problem on BMP image resize using PHP - php

Question

I have a PHP script to re size image file as below;
$file = "test.bmp";
$ext = pathinfo($file, PATHINFO_EXTENSION);
$info = pathinfo($file);
$file_name = basename($file,'.'.$info['extension']);
$thumbname = "thumb/".$file_name.".".$ext;
$maxh = 200;
$maxw = 200;
$quality = 100;
list($width,$height)=getimagesize($file);
$src = imagecreatefromwbmp($file);
$tmp = imagecreatetruecolor($maxw,$maxh);
imagecopyresampled($tmp,$src,0,0,0,0,200,200,$width,$height);
imagejpeg($tmp,$thumbname,$quality);
imagedestroy($tmp);
The script is suppose to resize a Windows bitmap image to 200x200 thumbnail. But instead, I am getting a black 200x200 image. I am using PHP with Apache in Windows PC. How can I fix this?

Answer 1

.bmp and wbmp are VERY, VERY different file types.
Note the content-type headers:
Content-Type: image/x-xbitmap
Content-Type: image/vnd.wap.wbmp
Calling imagecreatefromwbmp($file) where $file is a .bmp will fail every time.
See this thread for info on how to load a .bmp file. It's not pretty.

Answer 2

As pointed out in PHP imagecopyresampled() docs:
Note:
There is a problem due to palette image limitations (255+1 colors). Resampling or filtering an image commonly needs more colors than 255, a kind of approximation is used to calculate the new resampled pixel and its color. With a palette image we try to allocate a new color, if that failed, we choose the closest (in theory) computed color. This is not always the closest visual color. That may produce a weird result, like blank (or visually blank) images. To skip this problem, please use a truecolor image as a destination image, such as one created by imagecreatetruecolor().
To see if it's the case you can use imageistruecolor() and copy the contents to a new truecolor image before "copyresampling" it:
if( !imageistruecolor($src) ){
$newim = imagecreatetruecolor( $width, $height );
imagecopy( $newim, $src, 0, 0, 0, 0, $width, $height );
imagedestroy($src);
$src = $newim;
}

Answer 3

There is a new opensource project on Github that allows reading and saving of BMP files (and other file formats) in PHP.
The project is called PHP Image Magician.

Answer 4

<?php
//Create New 'Thumbnail' Image
$newImageWidth = 200;
$newImageHeight = 200;
$newImage = imagecreatetruecolor($newImageWidth, $newImageHeight);
$newImageFile = 'output.jpg';
$newImageQuality = 100;
//Load old Image(bmp, jpg, gif, png, etc)
$oldImageFile = "test.jpg";
//Specific function
$oldImage = imagecreatefromjpeg($oldImageFile);
//Non-Specific function
//$oldImageContent = file_get_contents($oldImageFile);
//$oldImage = imagecreatefromstring($oldImageContent);
//Get old Image's details
$oldImageWidth = imagesx($oldImage);
$oldImageHeight = imagesy($oldImage);
//Copy to new Image
imagecopyresampled($newImage, $oldImage, 0, 0, 0, 0, $newImageWidth, $newImageHeight, $oldImageWidth, $oldImageHeight);
//Output to file
imagejpeg($newImage, $newImageFile, $newImageQuality);