creating thumnails with gd

[nobodyk]

Can anyone guide me on how to create thumbnails with php/gd. I'm trying to use gd to create thumbnails and then store in in my server. I'm currently using a function in my script, but some thumbnails come out black.

 

Here's part of the code:

			if (($extension == "jpeg") || ($extension == "jpg")) $originalImage = ImageCreateFromJPEG($sourceImagePath);
			elseif ($extension == "gif") $originalImage = ImageCreateFromGIF($sourceImagePath);
			elseif ($extension == "png") $originalImage = ImageCreateFromPNG($sourceImagePath);
			elseif($extension == "bmp") $originalImage = ImageCreateFromWBMP($sourceImagePath);  // removed since Windows BMP is not supported
			$newImage = ImageCreateTrueColor($new_x, $new_y);
			ImageCopyResampled($newImage, $originalImage, 0, 0, $srcx, $srcy, $new_x, $new_y, $srcw, $srch);

			ImageJPEG($newImage, $imagePath, $outputImageQuality);
			ImageDestroy($newImage);
			ImageDestroy($originalImage);