How do image and text difference scores work? - AlertBits


How do image and text difference scores work?

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AlertBits Team  •  15 May 2023

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AlertBits can calculate an image and text difference score for your captures to help you identify changes and sort/filter through them easily.

When you add a new page and the very first capture is taken, the screenshot image and the text of the webpage are saved with that capture; and this initial capture doesn't have an image/text difference score (N/A).

However, for every capture taken afterward, that capture's screenshot image and webpage text is compared with the previous most recently taken capture.

Image difference scores are only available for PNG captures. For text difference scores, the text of the webpage is saved as well (up to 15,000 characters).

The 2 captures' images and texts are compared and given a difference score between 0% and 100%.

A 0% score means that the images or texts are exactly similar or equal and a 100% score means the images or texts are completely different.

In reality, screenshot images with a difference score of 15% or below likely mean that the images are the same and the webpage didn't change much if at all.

And a score of 25% or above likely means some changes have happened to the page compared to the previous capture.

While the text difference scores are fairly consistent, the image difference scores (and the level or range by which they vary) can be different for different webpages.

Since there is often a lot of empty white space in webpages, the image difference scores usually won't go very high.

So the idea is to use both the image and text difference scores as a guide to understand the different changes that happened to the image and the text of a webpage respectively.

Thus, if you have a lot of captures, try sorting them based on image or text differences in descending order. This will show you all the captures where the most significant changes happened.

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AlertBits Team

AlertBits content and editorial team.

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