imagepng

add a note User Contributed Notes

bart at resolume dot com
06-Apr-2006 11:54


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 11:22


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
25-Dec-2005 05:17


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 11:00


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
21-May-2005 02:50


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 10:40


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.

15-Apr-2005 03:11


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 06:03


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

11-Nov-2004 06:08


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
24-Aug-2004 04:43


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 10:49


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 09:14


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);



?>

24-Jan-2003 02:20


"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 08:41


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 09:37


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 10:34


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

imagepng

说明