From: sriram dot natarajan at gmail dot com Operating system: unix/linux PHP version: 5.3SVN-2009-09-28 (snap) PHP Bug Type: Feature/Change Request Bug description: PHP GD library can use underlying JPEG library's capability to prescale image
Description: ------------ GD library is commonly used in PHP5 applications for image processing. When creating thumbnails from a large jpeg image, the original image currently has to be decoded to a full-size copy before being resampled or resized. This is a relatively expensive step. The underlying jpeg library has a capability of prescaling an image when it is being decoded, so for example the decoded image could be only 1/16 the size of the fullsize image by prescaling by a factor of 4. This saves a substantial amount of cpu time. Expected result: ---------------- we can update php libgd library and our php gd extension to leverage underlying jpeg's ability to prescale image at the time of creating jpeg images. for example, we can introduce new API or patch our existing gdImageCreateFromJpeg API to have an extra argument for prescale size so that we can set the value of 'prescale' value like below cinfo.scale_denom = prescale; before calling "jpeg_start_decompress (&cinfo)" function. [credits: thanks to Richard Smith for coming up with this nice suggestion] af course, this will allow users to invoke our 'imagecreatefromjpeg' with an optional argument which specifies the prescale size of this jpeg. $src_img=imagecreatefromjpeg($name, 4); Actual result: -------------- better performance while producing jpeg based thumbnails -- Edit bug report at http://bugs.php.net/?id=49696&edit=1 -- Try a snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=49696&r=trysnapshot52 Try a snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=49696&r=trysnapshot53 Try a snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=49696&r=trysnapshot60 Fixed in SVN: http://bugs.php.net/fix.php?id=49696&r=fixed Fixed in SVN and need be documented: http://bugs.php.net/fix.php?id=49696&r=needdocs Fixed in release: http://bugs.php.net/fix.php?id=49696&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=49696&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=49696&r=needscript Try newer version: http://bugs.php.net/fix.php?id=49696&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=49696&r=support Expected behavior: http://bugs.php.net/fix.php?id=49696&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=49696&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=49696&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=49696&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=49696&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=49696&r=dst IIS Stability: http://bugs.php.net/fix.php?id=49696&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=49696&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=49696&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=49696&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=49696&r=mysqlcfg
