[RESOLVED] Problem with Image Resizer

Maharg105

Hi Guys,

I am currently using the following code to resize user images as they are being uploaded for use in an on site slideshow.

The code is as follows;

$twidth = "700";   // Maximum Width For Thumbnail Images
	$theight = "492";   // Maximum Height For Thumbnail Images 

$simg = imagecreatefromjpeg("$target_path_upload" . $file_name); //Make a temporary image for resizing

$currwidth = imagesx($simg);   // Current Image Width 
$currheight = imagesy($simg);   // Current Image Height

if ($currheight > $currwidth) {   // If Height Is Greater Than Width 
         $zoom = $twidth / $currheight;   // Length Ratio For Width 
         $newheight = $theight;   // Height Is Equal To Max Height 
         $newwidth = $currwidth * $zoom;   // Creates The New Width 
      } else {    // Otherwise, Assume Width Is Greater Than Height (Will Produce Same Result If Width Is Equal To Height) 
        $zoom = $twidth / $currwidth;   // Length Ratio For Height 
        $newwidth = $twidth;   // Width Is Equal To Max Width 
        $newheight = $currheight * $zoom;   // Creates The New Height 
      }

$dimg = imagecreate($newwidth, $newheight);   // Make New Image For Thumbnail 
      imagetruecolortopalette($simg, false, 256);   // Create New Color Pallete 
      $palsize = ImageColorsTotal($simg); 
      for ($i = 0; $i < $palsize; $i++) {   // Counting Colors In The Image 
       $colors = ImageColorsForIndex($simg, $i);   // Number Of Colors Used 
       ImageColorAllocate($dimg, $colors['red'], $colors['green'], $colors['blue']);   // Tell The Server What Colors This Image Will Use 
      } 
      imagecopyresized($dimg, $simg, 0, 0, 0, 0, $newwidth, $newheight, $currwidth, $currheight);   // Copy Resized Image To The New Image (So We Can Save It) 

 imagejpeg($dimg, "$target_path_upload" . $file_name);   // Saving The Image 
      imagedestroy($simg);   // Destroying The Temporary Image 
      imagedestroy($dimg);   // Destroying The Other Temporary Image

The problem is that sometimes the image's dimensions are large than the 700 x 492 that I have specified at the top of the code.

Also the images are of very poor quality once the script has resized them, even if they are being scaled down.

I wondered if anyone might have any insight.
As always, thanks in advance.

Weedpacket

The page for [man]imagecopyresized[/man] notes that [man]imagecopyresampled[/man] produces better results. Also, all the palette stuff is unnecessary since you're converting a JPEG into a JPEG; you certainly don't need to map everything to 256 colours. In short, that whole second-to-last paragraph would be replaced by a call to [man]imagecopyresampled[/man].

For your main problem: I'm not seeing anything wrong right now; do you mean the output image is sometimes too large? What are the dimensions of the original and what do they get scaled to?

bradgrafelman

I also believe that you might get slightly better results if you use [man]imagecreatetruecolor/man instead of [man]imagecreate/man for the new image.

EDIT: Also note that [man]imagejpeg/man has a $quality parameter; the manual suggests that the default is about 75, so perhaps you could try increasing that as well? I would suggest trying something around 90 or so.

Maharg105

Hey Guys,

Thanks for the help. I have taken Weedpacket's advice and used imagecopyresampled() which has improved my results no end.

The pictures are still going over the maximum dimensions given by the script. They generally are exactly 700px wide and then are about 510 - 520px high which is outside of 492px parameter given. I can't see why, given the code, this is occuring.

The new code is as follows;

	$twidth = "700";   // Maximum Width For Thumbnail Images
	$theight = "492";   // Maximum Height For Thumbnail Images 



$currwidth = imagesx($simg);   // Current Image Width 
$currheight = imagesy($simg);   // Current Image Height

if ($currheight > $currwidth) {   // If Height Is Greater Than Width 
         $zoom = $twidth / $currheight;   // Length Ratio For Width 
         $newheight = $theight;   // Height Is Equal To Max Height 
         $newwidth = $currwidth * $zoom;   // Creates The New Width 
      } else {    // Otherwise, Assume Width Is Greater Than Height (Will Produce Same Result If Width Is Equal To Height) 
        $zoom = $twidth / $currwidth;   // Length Ratio For Height 
        $newwidth = $twidth;   // Width Is Equal To Max Width 
        $newheight = $currheight * $zoom;   // Creates The New Height 
      }

// Resample
$image_p = imagecreatetruecolor($newwidth, $newheight);
$image = imagecreatefromjpeg($complete_path_upload);
imagecopyresampled($image_p, $image, 0, 0, 0, 0, $newwidth, $newheight, $currwidth, $currheight);

// Save File
imagejpeg($image_p, "$target_path_upload" . $file_name);
imagedestroy($image_p);  // Destroying The Other Temporary Image

Thanks again for any help you can give.

Thanks,

Maharg105

Finally figured it out. My sizing problem was because I hadn't used the correct formula to ensure that the aspect ratio was maintained when resizing.

In case anybody might find this useful. I am using the current code.

move_uploaded_file($file_tmp, $complete_path_upload);
	$twidth = "700";   // Maximum Width For Thumbnail Images
	$theight = "492";   // Maximum Height For Thumbnail Images 

$image = imagecreatefromjpeg($complete_path_upload);

$currwidth = imagesx($image);   // Current Image Width 
$currheight = imagesy($image);   // Current Image Height

$x_ratio = $twidth / $currwidth; 
         $y_ratio = $theight / $currheight; 

     if( ($currwidth <= $twidth) && ($currheight <= $theight) ) 
     { 
		   $newwidth = $currwidth; 
           $newheight = $currheight; 
     } 
     elseif (($x_ratio * $currheight) < $theight) 
     { 
           $newheight = ceil($x_ratio * $currheight); 
           $newwidth = $twidth; 
     } 
     else 
     { 
           $newwidth = ceil($y_ratio * $currwidth); 
           $newheight = $theight; 
     } 

// Resample
$image_p = imagecreatetruecolor($newwidth, $newheight);

imagecopyresampled($image_p, $image, 0, 0, 0, 0, $newwidth, $newheight, $currwidth, $currheight);

// Save File
imagejpeg($image_p, "$target_path_upload" . $file_name);
imagedestroy($image_p);  // Destroying The Temporary Image

Thanks again for the help guys,