In PHP, imagepng() accepts a filter parameter. How do these filters affect the function's output?

Posted by Joe Lencioni on Stack Overflow See other posts from Stack Overflow or by Joe Lencioni
Published on 2010-06-15T19:32:30Z Indexed on 2010/06/15 19:52 UTC
Read the original article Hit count: 212

Filed under:

php

|

image

|

png

|

gdlib

|

php-gd

How do these filters affect the output of imagepng() in PHP?

PNG_NO_FILTER
PNG_FILTER_NONE
PNG_FILTER_SUB
PNG_FILTER_UP
PNG_FILTER_AVG
PNG_FILTER_PAETH
PNG_ALL_FILTERS

The documentation simply says, "A special PNG filter, used by the imagepng() function" for each of them.

It seems that using PNG_NO_FILTER will reduce the filesize of the output, but other than that, I am unsure as to how it is affected. Any insight would be really appreciated.

© Stack Overflow or respective owner

Related posts about php

Magento, NGINX, PHP-FPM, APC, MEMCACHED, 16gb Ram CentOS, Spiking PHP-FPM to 100% CPU

as seen on Server Fault - Search for 'Server Fault'
I have been trying to resolve my issue of spiking cpu caused by php-fpm processes. I've reduced the php-fpm config settings to: pm = ondemand pm.max_children = 12 pm.start_servers = 2 pm.min_spare_servers = 2 pm.max_spare_servers = 10 pm.max_requests = 500 php_admin_value[memory_limit] = 128M Problem… >>> More
PHP Pear Installation on CentOS

as seen on Server Fault - Search for 'Server Fault'
[root@ip ~]# yum install php-pear* Reducing CentOS-5 Testing to included packages only Finished Setting up Install Process Package 1:php-pear-1.8.1-2.el5.centos.noarch already installed and latest versio … >>> More
Apache configurations for php "AddType text/html php" or "AddType application/x-httpd-php php .php"

as seen on Server Fault - Search for 'Server Fault'
I am taking over an application server and discover that it contain the following settings: AddType text/html php Although it works, but my understanding is that it should set as following: AddType application/x-httpd-php php .php What are the key differences between the two settings?… >>> More
mod_rewrite settings causes server to throw HTTP 500 errors instead of 404

as seen on Server Fault - Search for 'Server Fault'
Hello. I have a server with VBulletin forum (working under Apache 2.2, CentOS). The default settings for it in .htaccess are as follows: RewriteEngine on RewriteCond %{HTTP_HOST} ^gsmforum\.ru RewriteRule (.*) http://www.gsmforum.ru/$1 [R=301,L] # If you are having problems or are using VirtualDocumentRoot… >>> More
Problems installing Memcache (PECL extension)

as seen on Server Fault - Search for 'Server Fault'
I have installed memcached fine, and now I will need to install PECL extension memcache. Im running RedHat x86_64 es5. The installation gives me this: downloading memcache-2.2.6.tgz ... Starting to download memcache-2.2.6.tgz (35,957 bytes) ..........done: 35,957 bytes 11 source files, building running:… >>> More

Related posts about image

Image anotation (Highlighting parts of an image, Scrubbing an image) using Javascript

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, We are working on an application and would like users to annotate an image. By annotation I mean, the ability to highlight parts of an image. Once the image is highlighted, and submit is clicked, the highlighted attributes (color, area highlighted) are submitted to the server to be stored in… >>> More
How I can add JScroll bar to NavigableImagePanel which is an Image panel with an small navigation vi

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have the following NavigableImagePanel, it is under BSD license and I found it in the web. What I want to do with this panel is as follow: I want to add a JScrollPane to it in order to show images in their full size and let the users to re-center the image using the small navigation panel… >>> More
Twitter Bootstrap styling conflicts with plug-ins like jqGrid and other third part libraries

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
Issues:The concern is that the Twitter Bootstrap framework is that some of their css selectors are simply too generic and have incompatibility issues and conflicts with most third party plug-ins and css libraries, like jQuery-UI and jqGrid.My most pressing concern is only with the generic selector… >>> More
PHP invalid image's and error handling

as seen on Stack Overflow - Search for 'Stack Overflow'
Using PHP's Image and GD functions you can use the following method to finally output the php image imagepng($image); Sometimes, for whatever reason the image may not be displayed typically the error is not with the image but with the actual php functions not executing successfully. However this… >>> More
apt-get install was interrupted

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I am new to Ubuntu. I got the following lines after an interrupted apt-get install. Running depmod. update-initramfs: deferring update (hook will be called later) Examining /etc/kernel/postinst.d. run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.13.0-29-generic /boot/vmlinuz-3.13.0-29-generic run-parts:… >>> More