imagepolygon

Last updated: Fri, 01 Aug 2008

imagepng

(PHP 4, PHP 5)

imagepng — Output a PNG image to either the browser or a file

Description

bool imagepng ( resource $image [, string $filename [, int $quality [, int $filters ]]] )

Outputs or saves a PNG image from the given image .

Parameters

image: An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
filename: The path to save the file to. If not set or NULL, the raw image stream will be outputted directly.

Note: NULL is invalid if the quality and filters arguments are not used.
quality: Compression level: from 0 (no compression) to 9.
filters: Allows reducing the PNG file size. It is a bitmask field which may be set to any combination of the PNG_FILTER_XXX constants. PNG_NO_FILTER or PNG_ALL_FILTERS may also be used to respectively disable or activate all filters.

Return Values

Returns TRUE on success or FALSE on failure.

ChangeLog

Version	Description
5.1.3	Added the `filters` parameter.
5.1.2	Added the `quality` parameter.

Examples


<?php
$im = imagecreatefrompng("test.png");
imagepng($im);
?>


@ phpman at texmedia dot de:



The compression range in PNG is in range 0-9, i think if you specified a compression level higher than 9, it'll be completely "compressed", or suppressed in the other words.



The compression level is originally for JPEG, which is in range 0 - 100, I think it'll work fine if you divide it by ten before passing to imagepng(). ;)

Jeff Sauro
14-Nov-2007 01:39


My webserver, running 5.14 didn't like the header that was generated using imagepng(). It works find on my local test server and on 4.x from another host. 



The generated image displays in the browser (IE, firefox) but when saved to a file or inserted into an RTF file, the image was corrupted. As a test, when attempting to right-click to save as, the image format was not recognized. 



The only work-around appears to be adding the additional paramaters. 



So instead of just 

imagepng($image); //DIDNT WORK--CORUPT IMAGE



This worked

imagepng($image,NULL,0,NULL);



and saving to disk, this worked:

imagepng($image,$file_location,0,NULL);



Jeff

phpman at texmedia dot de
28-Oct-2007 12:06


When changeing the PHP version from 4 to 5 I found out, that PHP5 handles imagepng() more restrictive than in PHP4. I'd used 



imagepng($image,'',90);



to reduce the image quality whithout saving the image as a file. The quality parameter is not supported at all, I used imagejpg before and simply changed the function to imagepng whithout taking care of the existing parameters. It did not matter and there was no error in PHP4. But in PHP5, the image will not be shown anymore. So you have to remove it to have the standard:



imagepng($image);

teemu
08-Mar-2007 03:32


Filter constants are listed on libpng site http://www.libpng.org/pub/png/libpng-1.2.5-manual.html#section-5.9

alex at gateway-productions dot com
09-Jan-2007 01:17


barts code below does not work at least with gd 2



Only returns a blank image with alpha not the source resized



        $im = ImageCreateFromPNG($sourcefile);

        $im_dest = imagecreatetruecolor ($forcedwidth, $forcedheight);

        imagealphablending($im_dest, false);

        imagecopyresampled($im_dest, $im, 0, 0, 0, 0, $wm_width, $wm_height, $forcedwidth, $forcedheight);

        imagesavealpha($im_dest, true);

        imagepng($im_dest, $destfile);

        imagedestroy($img_dest);



ps you also forgot image destroy and you had a random var in imagepng undefined in your post

bart at resolume dot com
06-Apr-2006 06:54


If you want to resize a png-24 image and preserve the alpha channel you need to set imagealphablending($im_dest, false) on the destination image just after creating it with imagecreatetruecolor() and do a imagesavealpha($im_dest, true) on it before saving it:



<?php



$im = ImageCreateFromPNG('redfade.png');



$im_dest = imagecreatetruecolor (500, 300);

imagealphablending($im_dest, false);



imagecopyresampled($im_dest, $im, 0, 0, 0, 0, 300, 300, 500, 300);



imagesavealpha($im_dest, true);

imagepng($im_re, 'small_redfade.png');



?>

adrenalin at NOSPAM dot myrealbox dot com
27-Dec-2005 05:22


Trying to resize a png 256 colors image and save it in 256 colors with a correct color palette ? (if you'll save a 256 color image in truecolor palette the result image will have a big size).

I spent some hours trying various function to get a good quality 256 color png image, but because of color palette the result image quality was awful.

But thank to the comment of zmorris at zsculpt dot com from imagetruecolortopalette function page, i figured out how to get a properly image!



<?php

function resize_png($src,$dst,$dstw,$dsth) {

    list($width, $height, $type, $attr) = getimagesize($src);

    $im = imagecreatefrompng($src);

    $tim = imagecreatetruecolor($dstw,$dsth);

    imagecopyresampled($tim,$im,0,0,0,0,$dstw,$dsth,$width,$height);

    $tim = ImageTrueColorToPalette2($tim,false,255);

    imagepng($tim,$dst);

}

//zmorris at zsculpt dot com function, a bit completed

function ImageTrueColorToPalette2($image, $dither, $ncolors) {

    $width = imagesx( $image );

    $height = imagesy( $image );

    $colors_handle = ImageCreateTrueColor( $width, $height );

    ImageCopyMerge( $colors_handle, $image, 0, 0, 0, 0, $width, $height, 100 );

    ImageTrueColorToPalette( $image, $dither, $ncolors );

    ImageColorMatch( $colors_handle, $image );

    ImageDestroy($colors_handle);

    return $image;

}

?>



Good luck,

Namolovan Nicolae, Moldova

awalton at gmail dot com
24-Dec-2005 11:17


PNG images (as any image) can be stored in a MySQL blob field, but if you want to do this, you'll want to serialize the image stream into a better form. I would recommend base64_encode() and base64_decode(). (Just fopen() the file, fread() the contents in, base64_encode() the string, and fire off your SQL query (use addslashes()/stripslashes() to be more secure)). 



This has been posted an innumerable amount of times throughout the site, but it's still terrible that a lot of users simply don't understand this and use it to its full potential. 



I would also recommend that if you are doing images this way, to keep an image cache folder somewhere that PHP can access (possibly even somewhere off your webroot?). That way if your website is swamped with traffic it won't kill the SQL server.

vladson at pc-labs dot info
04-Jul-2005 06:00


To send 'Content-Length' header (like in static pictures case) i use "Output handler" like this...

<?php

//    Output handler

function output_handler($img) {

    header('Content-type: image/png');

    header('Content-Length: ' . strlen($img));

    return $img;

}



//    Image output

ob_start("output_handler");

imagepng($im);

ob_end_flush();

?>

neburk0rk at gmail dot com
20-May-2005 09:50


This is my way to store PNG-images in a MySQL database... You cannot directly store the PNG-image in a variable, and then parse it in the database, cos if you try to define it to a variable, it'll still just output it...

In my method i use three functions

 to "capture" the output and store it in a variable; ob_start (to start the output buffering),    ob_get_contents  (to capture the output),    and  ob_end_clean (to erase the cache, and end the output buffering)



<?php

$imagefile = "changethistogourimage.gif";



$image = imagecreatefromgif($imagefile);

ob_start();

imagepng($image);

$imagevariable = ob_get_contents();

ob_end_clean();



/*

HERE YOU CAN MESS WITH THE $imagevariable AS YOU LIKE

*/

?>

php at no dot spam dot prosa dot net
04-May-2005 05:40


You could use the function imagecreatefrompng 



(I assume that you already know how to get the text from the url.)



The only thing left to do is put that text on the image using the correct colors for you.



<?php



$im = @imagecreatefrompng($imgname); 



$text_color = imagecolorallocate ($im, $Red,$Green,$Blue);



imagestring ($im, 3,  5, 15,  $SomeTextFromURL, $text_color);



?>



Regards,

Peter Berkhout.

14-Apr-2005 10:11


To cbrasho at yahoo dot com



I have read your note and the note that was made in reply. My SIMPLE solution is to add a key to each image record in the database so that the ID+Key pair will be used very similarly to a Username+Password pair =) all you have to do is create a unique random number or something to put in the "Key" field of the database when the entry is made.



i've modified the code and pasted it here...



<?php

//get file ID+Key

$id = $_REQUEST['id'];

$key = $_REQUEST['key']; // i added this!



//get data from blob

$sql = "SELECT Data, Type, Extension FROM Images WHERE ID=$id AND Key=$key"; // this is the clever bit =D

$records=mysql_query($sql);

$record=mysql_fetch_row($records);



$data=$record['Data'];

$type=$record['Type'];

$ext=$record['Extension'];



//output data

header("Content-Type: $type");

header("Content-Disposition: inline; filename=img$id.$ext");



echo $data;

?>



all i did was add 1 line and change another =D



now if "image.php?id=1&key=A29F1X" gives a result, "image.php?id=2&key=A29F1X" will output an image of zero bytes in size because the keys in the database are unique =)

dws at mrao dot cam dot ac dot uk
22-Jan-2005 12:03


Presumably it returns true on success and false on failure, although the documentation doesn't actually say so.

11-Nov-2004 12:08


To cbrasho at yahoo dot com



I don't get the problem. If you want to have images stored as blobs, you can do a show.php like this:



<?php

//get file ID

$id = $_REQUEST['id'];



//get data from blob

$sql = "SELECT Data, Type, Extension FROM Images WHERE ID=$id";

$records=mysql_query($sql);

$record=mysql_fetch_row($records);



$data=$record['Data'];

$type=$record['Type'];

$ext=$record['Extension'];



//output data

header("Content-Type: $type");

header("Content-Disposition: inline; filename=img$id.$ext");



echo $data;

?>



I've done this many times (conceptually), and it works like a charm, although I would recommend a little more security on that indata. If you have a unified place images go in (like an upload form), you can even drop the type and extension part by saving every image as the same filetype.

pm at dontspamme dot pietmarcus dot com
23-Aug-2004 11:43


in reply to: cbrasho at yahoo dot com



if you use Apache as a webserver, you could do the following:



You could set up a 'img' directory in your webspace.

In that directory there will be two files: a .htaccess file and a img.php file

the .htaccess file contains the following code:

ErrorDocument 404 /img/img.php



the img.php file looks something like this:



<?php

  $file = $_SERVER['REDIRECT_URL'];



  $result = mysql_query('select img_blob from images where filename=\\'' . $file . '');

  list($blob) = mysql_fetch_row($result);



  header('HTTP/1.0 200 Ok');

  header("Content-type: image/jpeg");

  

  print $blob; # or whatever works, I don't use this

?>



if you use a url for your image like http://test.com/img/image1.jpeg, which doesn't exist, normally you would get a 404-page. in this case, the 404 is being handled by img.php, which brings up the required image...

cbrasho at yahoo dot com
17-Aug-2004 05:49


Having your pictures stored in a database sounds great but brings you a lot of trouble.

Storing images in a DB you will have a script show.php that will appear in <img> tags: <img src='show.php?img_id=$some_id'>

But if you want to have REGISTER GLOBALS = OFF, you are in trouble and there is no way (at leas as far as i know) to solve the problem but to put te img from the DB in a file and put the coresponding file name in the <img> tag. But this brings another problem: simultaneous accesses to the page. So you will have to find a way to give unique names to the picture files for each simultaneous access to the page. The solution might be using sessions. This is how you end up having a very compleh PHP script for a very simple problem. So, the basic ideea is " do not store your pictures in a blob unless you know exactly what you are doing".

mail at stefanbechtold dot de
17-Apr-2003 04:14


to all the ones, who like having their users fill their profil with an image without destroying a fixed design the following should be a great way to handle this problem.



this file opens a picture from $imagepath and returns it as a valid picture to embed in: <img src="file.php?image=123.jpg[?maxX=200&maxY=150]"> (in [] = optional)



but this file does more than this. it also adds black borders to files that are smaller than the max. size, so adding borders to the left and right where a image is too high :-)



if there is a need for a copyright note this script will also help you. you can put in a various text to $copyright. the text length should be in relationship to $maxX and $maxY.



Well there are other features of the script, just try'em out and have fun with it :-)



bye 



<?php



# standard height & weight if not given

if(!isset($maxX)) $maxX = 100;

if(!isset($maxY)) $maxY = 75;



# colour- & textvalues

$picBG = "0,0,0"; # RGB-value !

$picFG = "104,104,104"; # RGB-value !

$copyright = "stefan bechtold"; 

$font = 1;



# minimal & maximum zoom

$minZoom = 1; # per cent related on orginal (!=0)

$maxZoom = 200; # per cent related on orginal (!=0)



# paths

$imgpath = "userimages/"; # ending with "/" !

$nopicurl = "../images/nopic.jpg"; # starting in $imagepath!!!

$nofileurl = "../images/nofile.jpg"; # starting in $imagepath!!!



if(!isset($image) || empty($image))

    $imageurl = $imgpath . $nopicurl;

elseif(! file_exists($imgpath . trim($image)))

    $imageurl = $imgpath . $nofileurl;

else

    $imageurl = $imgpath . trim($image);



# reading image

$image = getImageSize($imageurl, $info); # $info, only to handle problems with earlier php versions...

switch($image[2]) {

      case 1:

       # GIF image

        $timg = imageCreateFromGIF($imageurl);

        break;

    case 2:

       # JPEG image

        $timg = imageCreateFromJPEG($imageurl);

        break;

    case 3:

       # PNG image

        $timg = imageCreateFromPNG($imageurl);

        break;

}



# reading image sizes

$imgX = $image[0];

$imgY = $image[1];



# calculation zoom factor 

$_X = $imgX/$maxX * 100;

$_Y = $imgY/$maxY * 100;



# selecting correct zoom factor, so that the image always keeps in the given format

# no matter if it is more higher than wider or the other way around

if((100-$_X) < (100-$_Y)) $_K = $_X;

else $_K = $_Y;



# zoom check to the original

if($_K > 10000/$minZoom) $_K = 10000/$minZoom;

if($_K < 10000/$maxZoom) $_K = 10000/$maxZoom;



# calculate new image sizes

$newX = $imgX/$_K * 100;

$newY = $imgY/$_K * 100;



# set start positoin of the image

# always centered 

$posX = ($maxX-$newX) / 2;

$posY = ($maxY-$newY) / 2;



# creating new image with given sizes

$imgh = imageCreateTrueColor($maxX, $maxY);



# setting colours

$cols = explode(",", $picBG);

$bgcol = imageColorallocate($imgh, trim($cols[0]), trim($cols[1]), trim($cols[2]));

$cols = explode(",", $picFG);

$fgcol = imageColorallocate($imgh, trim($cols[0]), trim($cols[1]), trim($cols[2]));



# fill background

imageFill($imgh, 0, 0, $bgcol);



# create small copy of the image

imageCopyResampled($imgh, $timg, $posX, $posY, 0, 0, $newX, $newY, $image[0], $image[1]);



# writing copyright note

imageStringUp($imgh, $font, $maxX-9, $maxY-3, $copyright, $fgcol);



# output

switch($image[2]) {

      case 1:

    # GIF image

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

        imageGIF($imgh);

    case 2:

    # JPEG image

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

        imageJPEG($imgh);

    case 3:

    # PNG image

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

        imagePNG($imgh);

}



# cleaning cache

imageDestroy($timg);

imageDestroy($imgh);



?>

23-Jan-2003 08:20


"Tip: As with anything that outputs its result directly to the browser, you can use the output-control functions (http://www.php.net/manual/en/ref.outcontrol.php) to capture the output of this function, and save it in a string (for example)."



ob_start();

imagepng($image);

$image_data = ob_get_contents();

ob_end_clean();



And now you can save $image_data to a database, for example, instead of first writing it to file and then reading the data from it. Just don't forget to use mysql_escape_string...

johnbeech at mkv25.net
20-Jan-2003 02:41


PNG files are already compressed. They use a lossless compression algorithm. If you are using HighColour images, the compression only does so much. For low colour images (16 or 256) the compression is much better.



It is pointless trying to compress the images further before sending to a browser.

bgd1977 at hotmail dot com
26-Jul-2002 04:37


I have experienced segfaults and bus errors with the following configuration: FreeBSD4.4, Apache 1.3.26, PHP 4.2.2, GD-1.8.4, PDFlib 4.0.1. The apache process crashed when calling the imagepng function, but it didn't crash when calling the imagejpg function, or imagecreatefrompng...



 Some wasted hours (lots) later, in which I have tried to recompile gd, libpng, php, libjpeg, what-not, I have found the following advices:

http://bugs.php.net/bug.php?id=16841



 So the problem was not with the png library, but rather with the PDFlib. Even though all the threads led to a png-problem... so I have simply upgraded to PDFlib 4.0.3 (w/o any special configure arguments; --with-libpng didn't work anyways), recompiled PHP, and now everything works (imagepng, pdf creation, etc.).



 Hope this helps,

 bogdan

ruelle at xtof dot com
17-Feb-2002 04:34


Better than a chmod 777 to any '/dir/pic.png' you should :

- test if dir is writable (is_writable func.)

- use chmod 700 (more secure because let only the webserver ID have access)



In any case you should program a (crontab) script to change the owner ID of any images created.

add a note