imagecreatefromgif

add a note User Contributed Notes

moxley at moxleydata dot com
10-Oct-2006 08:40


I wanted to find out if a GIF is Black & White or Color, but I didn't want to wait around for imagecreatefromgif() to parse a 200k file (about 1 second) to get the color map, so I wrote this function to get a list of all the colors in the GIF. Hope it is useful for you.



<?php

function getGIFColorMap($file)

{

   $fp = fopen($file, 'r');

   $buf = fread($fp, 1024);

   fclose($fp);

      

   // Calculate number of colors

   // buf[10] is the color info byte

   $color_byte = ord($buf[10]);

   $has_color_map = ($color_byte >> 7) & 1;

   $color_res = (($color_byte >> 4) & 7) + 1;

   $bits_per_pixel = ($color_byte & 7) + 1;

   $color_count = 1 << $bits_per_pixel;

      

   if (!$has_color_map) return null;

      

   // buf[13] is the beginning of the color map

   $color_map_index = 13;

   $map = array();

   for ($i=0; $i < $color_count; $i++) {

       $index = $color_map_index + $i*3;

       $r = ord($buf[$index]);

       $g = ord($buf[$index + 1]);

       $b = ord($buf[$index + 2]);

       $map[$i] = array($r, $g, $b);

   }

   return $map;

}

?>

moxley at moxleydata dot com
03-Oct-2006 01:48


I wanted to find out if a GIF is Black & White or Color, but I didn't want to wait around for imagecreatefromgif() to parse a 200k file (about 1 second) to get the color map, so I wrote this function to get a list of all the colors in the GIF. Hope it is useful for you.



<?php

function getGIFColorMap($file)

{

    $fp = fopen($file, 'r');

    $buf = fread($fp, 1024);

    fclose($fp);

        

    // Calculate number of colors

    // buf[10] is the color info byte

    $color_byte = ord($buf[10]);

    $has_color_map = ($color_byte >> 7) & 1;

    $color_res = (($color_byte >> 4) & 7) + 1;

    $bits_per_pixel = ($color_byte & 7) + 1;

        

    if (!$has_color_map) return null;

        

    // buf[13] is the beginning of the color map

    $color_map_index = 13;

    $map = array();

    for ($i=0; $i <= $bits_per_pixel; $i++) {

        $index = $color_map_index + $i*3;

        $r = ord($buf[$index]);

        $g = ord($buf[$index + 1]);

        $b = ord($buf[$index + 2]);

        $map[$i] = array($r, $g, $b);

    }

    return $map;

}



$colors = getGIFColorMap("big.gif");

foreach ($colors as $i=>$color) {

    echo "color[$i]: (red=$color[0], blue=$color[1], green=$color[2])\n";

}

?>

ZeBadger
06-Jul-2006 03:17


No it doesn't work with animated gifs.... which is why I wrote the code below to detect if a gif is animated or not.



My friends have been nagging me to code up something to resize animated gifs... but I imagine that this will be put into php/gd at some point.

mhbernheim at lasnite dot com
08-May-2006 03:20


doesn't seem to work with animated gifs, the frames are all messed up

razonklnbd at yahoo dot com
18-Dec-2005 03:35


this function will convert gif image to jpeg. it take three parameter as argument. two argument are optional

first will take the gif file name. second for file name to save the converted file. third argument is an color array



function gif2jpeg($p_fl, $p_new_fl='', $bgcolor=false){

  list($wd, $ht, $tp, $at)=getimagesize($p_fl);

  $img_src=imagecreatefromgif($p_fl);

  $img_dst=imagecreatetruecolor($wd,$ht);

  $clr['red']=255;

  $clr['green']=255;

  $clr['blue']=255;

  if(is_array($bgcolor)) $clr=$bgcolor;

  $kek=imagecolorallocate($img_dst,

                  $clr['red'],$clr['green'],$clr['blue']);

  imagefill($img_dst,0,0,$kek);

  imagecopyresampled($img_dst, $img_src, 0, 0, 

                  0, 0, $wd, $ht, $wd, $ht);

  $draw=true;

  if(strlen($p_new_fl)>0){

    if($hnd=fopen($p_new_fl,'w')){

      $draw=false;

      fclose($hnd);

    }

  }

  if(true==$draw){

    header("Content-type: image/jpeg");

    imagejpeg($img_dst);

  }else imagejpeg($img_dst, $p_new_fl);

  imagedestroy($img_dst);

  imagedestroy($img_src);

}



EXAMPLE:

$fl='http://www.suchona.com/test/testgif.gif';

$c['red']=255;

$c['green']=0;

$c['blue']=0;

gif2jpeg($fl, '', $c);



Thanks

Md. Shahadat Hossain Khan Razon

razon.phpxperts.com

ZeBadger
16-Dec-2005 01:15


I have written this code to detect if a gif file is animated or not.  I thought I would share it :-)



<?php



function is_ani($filename)

{

        $filecontents=file_get_contents($filename);



        $str_loc=0;

        $count=0;

        while ($count < 2) # There is no point in continuing after we find a 2nd frame

        {



                $where1=strpos($filecontents,"\x00\x21\xF9\x04",$str_loc);

                if ($where1 === FALSE)

                {

                        break;

                }

                else

                {

                        $str_loc=$where1+1;

                        $where2=strpos($filecontents,"\x00\x2C",$str_loc);

                        if ($where2 === FALSE)

                        {

                                break;

                        }

                        else

                        {

                                if ($where1+8 == $where2)

                                {

                                        $count++;

                                }

                                $str_loc=$where2+1;

                        }

                }

        }



        if ($count > 1)

        {

                return(true);



        }

        else

        {

                return(false);

        }

}



exec("ls *gif" ,$allfiles);

foreach ($allfiles as $thisfile)

{

        if (is_ani($thisfile))

        {

                echo "$thisfile is animated<BR>\n";

        }

        else

        {

                echo "$thisfile is NOT animated<BR>\n";

        }

}

?>



It could quite easily be modified to count the number of frames if you required.

steve at stevedix dot de
25-Oct-2005 03:20


If anyone is looking for the Yamasoft gif conversion utility :



Although Yamasoft's website is long gone, the code can be found on the following websites : 

 http://www.fpdf.org/phorum/read.php?f=1&i=9418&t=7568#9418



http://www.fpdf.org/download/php-gif.zip



http://phpthumb.sourceforge.net/index.php?source=phpthumb.gif.php

jason at null dot zzz
06-Apr-2004 05:13


thanks yamasoft for the gif to png lib.  it works!  but, there is one bug.  i changed line 1003 to this:



if(isset($this->m_img->m_bTrans) && $this->m_img->m_bTrans && ($nColors > 0)) {



because i was getting an error that m_bTrans is undefined.  i think this is because my gif has no transparency.  after i updated this line, there were no problems.



thanks!



-j

josh [ a t ] OnlineComics [ d o t ] net
08-Oct-2003 11:36


I just installed gif2png on my server, and it took a little research on my part to figure out that this...



passthru("$path/gif2png -O $image_path/image.gif")



will not work if safe mode is on. If you're on a shared server, it probably is. You don't need to turn safe mode off, however, just set the safe_mode_exec_dir variable in your php.ini file to the directory where you installed gif2png. Then you'll be able to execute the program from your PHP script.

29-Jun-2003 07:26


function LoadGif ($imgname) {

    $im = @ImageCreateFromGIF ($imgname); /* Attempt to open */

    if (!$im) { /* See if it failed */

        $im = ImageCreate (150, 30); /* Create a blank image */

        $bgc = ImageColorAllocate ($im, 255, 255, 255);

        $tc  = ImageColorAllocate ($im, 0, 0, 0);

        ImageFilledRectangle ($im, 0, 0, 150, 30, $bgc); 

        /* Output an errmsg */

        ImageString($im, 1, 5, 5, "Error loading $imgname", $tc); 

    }

    return $im;

}

19-Apr-2003 12:34


re: 09-May-2002 11:31



Seems gif2png is no longer at http://www.tuxedo.org/~esr/gif2png/

I found a Win32 version at http://www.r1ch.net/stuff/gif2png/

(for the Unix and source, see http://catb.org/~esr/gif2png/ )



In Win32,

  passthru("gif2png $filename");

works fine if gif2png.exe is in the path.

It will overwrite the file with .png extension, so be careful,or use temp files as in the post referenced above (without the  -O; type "gif2png" at the command line for the options).



I had a problem with exceeding the default 30 second execution time limit in PHP, so I added this line

  set_time_limit(0); // some odd gifs take a long time (example, a 25K gif, 700x700, mostly blank)

geoffrey at poulet dot org
27-Feb-2003 11:22


After hours of search, I've finally found a program which can convert JPG to GIF.

IJG - The Independent JPEG Group's JPEG software

Version 6 which support GIF (read and write with LZW)

and the version 6b which support GIF (write only without LZW)



The name of the file is: jpegsrc.v6.tar.gz

fezber at yamasoft dot com
13-Feb-2003 11:27


For users who just want GIF read (not write) support but:

1) Don't want to patch GD libs

2) Don't want to recompile something

3) Don't have permissions to install conversion packages

4) Any other reason...



I created a small php script (around 25KB) which lets you load a GIF from a file (you even can specify the image index on animated GIFs) and then convert it to a PNG or BMP file.



If I take one example:



<?

include("gif.php");



$gif = gif_loadFile("./test.gif");



if($gif) {

    // GIF file successfully opened

    if(gif_outputAsPNG($gif, "./test.png")) {

        // Now, just use ImageCreateFromPng...

        $img = ImageCreateFromPng("./test.png");



        if($img) {

            header("Content-Type: image/jpeg");

            ImageJPEG($img);

            ImageDestroy($img);

        }

        else {

            // Could NOT open PNG

        }

    }

    else {

        // Could NOT convert GIF to PNG...

    }

}

else {

    // GIF not loaded...

}

?>



Of course, it's slower than using appropriate software and/or libraries but it's quite useful for reading occasionaly some GIF files.



You'll find the gif.php source code at: http://www.yamasoft.com/php-gif.zip



Fabien

Ady at freebsd dot ady dot ro
12-Jan-2003 03:20


FreeBSD users are lucky to have the option of compiling GIF support in GD2.x through the ports system.

All you need to do is to export the "WITH_LZW=yes" global variable when compiling the graphics/gd2 port, e.g.:



# cd /usr/ports/graphics/gd2

# export WITH_LZW=yes

# make && make install



Then recompile and (re)install the www/mod_php4 port and you are in business... :)



Good luck!

unknown at hotmail dot com
15-Nov-2002 10:00


If GD doesn't support GIFs & gif2png is not available & you are not an administrator, you can install it in your account like this:



create do.php:

<? 

  global $do;

  passthru($do);

?>



then upload gif2png-2.4.6.tar.gz, unpack and install it:

do.php?do=tar+-xvzf+gif2png-2.4.6.tar.gz

do.php?do=gif2png-2.4.5/configure

do.php?do=make



Then remove all files except gif2png. Don't forget to remove do.php as it is a serious security hole in your system. 



Njoy!



Anze

senbei at terra dot es
10-May-2002 01:31


Since gif support is removed from the more recent GD libraries, you can still use it via an external program.


I've read somewhere about using ImageMagick and I tried myself but it's a quite big package and needs the X11 libs which are not available in some servers.


The other option I found is to use a little prog "gif2png" http://www.tuxedo.org/~esr/gif2png/


to convert gif files to png ones. It works under Unix and dos/win32/winnt and is very straightforward.


If you need to modify an user uploaded gif file to save it into your site just use this:





$path=$_FILES["photo"]["tmp_name"];


passthru("/usr/bin/gif2png -d -O ".$path);


$src_img=imagecreatefrompng( dirname($path)."/".basename($path, ".gif").".png");





This will convert the gif to a png and delete the gif file, then it will open the png with the GDlib so you can perform any operation on it.

philikon at gmx dot net
25-Jun-2001 11:50


Patches to the GD library that make GIF support available can be found at


http://www.rime.com.au/gd/

chuckg at infinite9 dot com
22-Mar-2001 04:05


I just thought I'd let you guys know of a workaround for the lack of Gif support in the latest GD...aside from adding the patch.  It works just as good, from what I can tell, and is quite nice ;)





Here goes:


<?


//Just grab some general image info


$img = "path/to/image.gif";


$imageInfo = GetImagesize($img);





if ( $imageInfo[2] == 1 ) {


   //it's a gif


   $file = fread(fopen($path, "r"), filesize($path));





   $fileHeader = "image/gif";


   Header("Content-Type: ".$fileHeader);


   echo $file;


   fclose($file);


}


?>





basically what that does is reads the file..through the "GetImageSize", which still returns if it's a GIF or not, (thank god), then if it's a gif, opens the file through normal filestream, sets the header to image type "gif" then prints it out.  Same as doing "ImageCreateFromGif($img)" and "ImageGif($img)", except that it doesn't require GD Gif support.  If you have any questions just ask me via email (chuckg@infinite9.com)

anthony dot atkins at vt dot edu
17-May-2000 09:05


<pre>


function myImageCreateFromGif($file_or_url) {





        $dummy_file = "/tmp/dummy.gif";





        # if this is a url, use fopen to get the file data, then 


        # save it to a dummy file


        if (preg_match("/(http|ftp):\/\//i", $file_or_url)) {


                # open the file using fopen, which supports remote URLs


                $input = fopen($file_or_url, "rb");





                # read the contents of the file


                # will accept files up to 10Mb, but will probably get 


                # and EOF before that, we have to do it this way because


                # filesize isn't designed to work with URLs.  sigh.


                $image_data = fread($input, 10000000);





                fclose($input);





                # write the contents to a dummy file


                $output = fopen("$dummy_file", "wb");


                fwrite($output, $image_data);


                fclose($output);





                # create the gif from the dummy file


                $image = ImageCreateFromGif($dummy_file);





                # get rid of the dummy file


                unlink($dummy_file);





        }





        # if it's not a URL, we can simply open the image directly


        else {


                $image = ImageCreateFromGif($file_or_url);


        }





        if ($image) { return $image; }


        else { return 0; }


}








if (!$url) { $url = "http://scholar.lib.vt.edu/images/cornholio.gif";}


$image = myImageCreateFromGif($url);





if ($image == "" || $image == 0) {


        print "<p>No Image data was returned...</p>\n";


}


else { 


        header("Content-Type: image/gif\n\n");


        ImageGif($image);


}





?>


</pre>

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