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opened 2020-05-29 17:22:02 +00:00 by sbrl · 1 comment

sbrl commented

2020-05-29 17:22:02 +00:00

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Website change detection with headless Firefox and ImageMagick

Have you ever wanted to know when a web page changes? If it does change, it's almost impossible to tell where on the page it's changed. Recently, I was thinking about the problem, and realised a few things:

Firefox can be operated headlessly (with --headless) to take screenshots
ImageMagick must be advanced enough to diff images

With this in mind, I set about implementing a script. Before we continue, here's an example diff image:

The bits that have changed appear in red. The script I've written also generates an animated PNG showing the difference too:

Pretty cool!

Website change detection with headless Firefox and ImageMagick -------------------------------------------------------------- Have you ever wanted to know when a web page changes? If it does change, it's almost impossible to tell _where_ on the page it's changed. Recently, I was thinking about the problem, and realised a few things: - [Firefox](https://firefox.com/) can be operated headlessly (with `--headless`) to take screenshots - [ImageMagick](https://imagemagick.org/) must be advanced enough to diff images With this in mind, I set about implementing a script. Before we continue, here's an example diff image: The bits that have changed appear in red. The script I've written also generates an [animated PNG](https://starbeamrainbowlabs.com/blog/article.php?article=posts/341-APNG-For-All.html) showing the difference too: Pretty cool!

sbrl commented

2020-05-29 17:26:14 +00:00

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We should finish this up, but we need a website to change so we can demo it!