Use PHP to convert PNG to JPG with compression

Question

I have a bunch of high quality PNG files   I want to use PHP to convert them to JPG because of it s smaller file sizes while maintaining quality   I want to display the JPG files on the web   Does PHP have functions libraries to do this     Is the quality compression any good

User · Answer

Be careful of what you want to convert  JPG doesn t support alpha-transparency while PNG does  You will lose that information   To convert  you may use the following function      Quality is a number between 0  best compression  and 100  best quality  function png2jpg  originalFile   outputFile   quality         image   imagecreatefrompng  originalFile       imagejpeg  image   outputFile   quality       imagedestroy  image       This function uses the imagecreatefrompng   and the imagejpeg   functions from the GD library

User · Answer

PHP has some image processing functions along with the imagecreatefrompng and imagejpeg function  The first will create an internal representation of a PNG image file while the second is used to save that representation as JPEG image file

User · Answer

Do this to convert safely a PNG to JPG with the transparency in white    image   imagecreatefrompng  filePath    bg   imagecreatetruecolor imagesx  image   imagesy  image    imagefill  bg  0  0  imagecolorallocate  bg  255  255  255    imagealphablending  bg  TRUE   imagecopy  bg   image  0  0  0  0  imagesx  image   imagesy  image    imagedestroy  image    quality   50     0   worst   smaller file  100   better   bigger file  imagejpeg  bg   filePath     jpg    quality   imagedestroy  bg

User · Answer

See this list of php image libraries  Basically it s GD or Imagemagick

User · Answer

This is a small example that will convert  image png  to  image jpg  at 70  image quality    lt  php  image   imagecreatefrompng  image png    imagejpeg  image   image jpg   70   imagedestroy  image     gt    Hope that helps

User · Answer

You might want to look into Image Magick  usually considered the de facto standard library for image processing  Does require an extra php module to be installed though  not sure if any which are available in a default installation   HTH

User · Answer

lt  php function createThumbnail  imageDirectory   imageName   thumbDirectory   thumbWidth         explode   explode       imageName        filetype    explode 1        if   filetype     jpg              srcImg   imagecreatefromjpeg   imageDirectory  imageName          else     if   filetype     jpeg              srcImg   imagecreatefromjpeg   imageDirectory  imageName          else     if   filetype     png              srcImg   imagecreatefrompng   imageDirectory  imageName          else     if   filetype     gif              srcImg   imagecreatefromgif   imageDirectory  imageName                origWidth   imagesx  srcImg        origHeight   imagesy  srcImg         ratio    origWidth    thumbWidth       thumbHeight    origHeight    ratio        thumbImg   imagecreatetruecolor  thumbWidth   thumbHeight       imagecopyresized  thumbImg   srcImg  0  0  0  0   thumbWidth   thumbHeight   origWidth   origHeight        if   filetype     jpg             imagejpeg  thumbImg    thumbDirectory  imageName          else     if   filetype     jpeg             imagejpeg  thumbImg    thumbDirectory  imageName          else     if   filetype     png             imagepng  thumbImg    thumbDirectory  imageName          else     if   filetype     gif             imagegif  thumbImg    thumbDirectory  imageName                  gt    This is a very good thumbnail script    Here s an example    path   The path to the folder where the original picture is   name   The filename of the file you want to make a thumbnail of   thumbpath   The path to the directory where you want the thumbnail to be saved into   maxwidth   the maximum width of the thumbnail in PX eg  100  wich will be 100px    createThumbnail  path   name   thumbpath   maxwidth

User · Answer

I know it s not an exact answer to the OP  but as answers have already be given     Do you really need to do this in PHP   What I mean is   if you need to convert a lot of images  doing it in PHP might not be the best way   you ll be confronted to memory limit  max execution time       I would also say GD might not get you the best quality size ratio   but not sure about that  if you do a comparison between GD and other solutions  I am very interested by the results  -     Another approach  not using PHP  would be to use Image Magick via the command line  and not as a PHP extension like other people suggested   You d have to write a shell-script that goes through all  png files  and gives them to either    convert to create a new  jpg file for each  png file or mogrify to directly work on the original file and override it     As a sidenote   if you are doing this directly on your production server  you could put some sleep time between bunches of conversions  to let it cool down a bit sometimes      I ve use the shell script   convert mogrify a few times  having them run for something like 10 hours one time   and they do the job really well  -

[php] Use PHP to convert PNG to JPG with compression?

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