Detecting if two png images are different

Posted by Benjol on Stack Overflow See other posts from Stack Overflow or by Benjol
Published on 2010-06-01T12:01:41Z Indexed on 2010/06/01 15:03 UTC
Read the original article Hit count: 141

Filed under:

.NET

|

diff

|

png

(Context: running autohotkey scripts to try and automate some tests. The plan is to take screenshots and then compare them to 'standard' screenshots to detect if output has changed).

Is there a 'clever' way to check if two png images are different?

By clever I mean other than comparing them byte by byte? (after having compared their size, obviously)

© Stack Overflow or respective owner

Related posts about .NET

Apt-Get Update: failure to fetch; can't connect to any sources

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I realize there are dozens of "apt-get update: failure to fetch" questions (I read through all I could find), but my present circumstance is unique to 12.04 and it affects all sources; not just launchpad. Additionally, I've tried several different servers in Europe and the U.S. as well as the "main… >>> More
12.04: Apt-Get Update: failure to fetch; can't connect to any sources

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I realize there are dozens of "apt-get update: failure to fetch" questions (I read through all I could find), but my present circumstance is unique to 12.04 and it affects all sources; not just launchpad. Additionally, I've tried several different servers in Europe and the U.S. as well as the "main… >>> More
What's New in ASP.NET 4

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
The .NET Framework version 4 includes enhancements for ASP.NET 4 in targeted areas. Visual Studio 2010 and Microsoft Visual Web Developer Express also include enhancements and new features for improved Web development. This document provides an overview of many of the new features that are included… >>> More
.NET Reflector 6, .NET Reflector Pro, TestDriven.NET, .NET 4.0 and Mono

as seen on Simple Talk - Search for 'Simple Talk'
By now you may well have noticed that .NET Reflector 6 and .NET Reflector Pro are out in the wild. The official launch happened today, although we actually put the software out last Thursday as part of a phased release plan to ensure that everything went smoothly today which, so far, it seems to have… >>> More
Redmine on Apache2 with Passenger issue

as seen on Server Fault - Search for 'Server Fault'
I installed Redmine and run it in Apache2 with the Passenger module. Apache2 boots, Passenger module gets loaded and the Redmine welcome page is shown, however when trying to login or navigate to other parts of the Redmine site, the browser keeps loading and loading and loading forever, although the… >>> More

Related posts about diff

newline-ignoring diff / diff across multiple lines / reflow-ignoring diff

as seen on Stack Overflow - Search for 'Stack Overflow'
Does anybody know of a diff-like tool that can show me the changes between two text files, but ignore changes in whitespace including newlines? Here's an example: the quick brown fox jumped over the lazy bear. the quick brown fox jumped over the lazy bear. the quick brown fox jumped over the… >>> More
Unix diff to only print relevant diff

as seen on Stack Overflow - Search for 'Stack Overflow'
I have these two files File:11 11 12345 File:22 123 456 Output of diff 11 22 2c2 < 456123 --- > 789 Output to be < 456123 > 789 I want it to not print 2c2 and "--" line. I looked at the man page but could not locate any help. Any ideas? The file has more than 1K lines >>> More
How to make meld prefer an SVN diff over a CVS diff

as seen on Stack Overflow - Search for 'Stack Overflow'
We have some directories that are tracked in both CVS and SVN (loooong story). When I change a file in one of these and run meld it diffs it against the SVN version. However for some of the other developers it diffs against CVS. Is there a way to specify which one gets priority? Everyone is using… >>> More
Is there a JS diff library against htmlstring just like google-diff-match-patch on plain text?

as seen on Stack Overflow - Search for 'Stack Overflow'
Currently I am using google-diff-match-patch to implement a real-time editing tool, which can synchronize texts between multiple users. Everything works great when operations are only plain texts, each user's operation(add/delete texts) could be diff-ed out by comparing to old text snapshot with the… >>> More
Paragraph-based diff program?

as seen on Stack Overflow - Search for 'Stack Overflow'
Does anyone know of a diff viewer or comparison program that can do paragraph-based differentials? My repos has a large number of LaTeX files that are formatted into 80-character wide paragraphs (for easy editing with vim). It's currently very difficult to interpret the diffs between various versions… >>> More