How to find the tolerance value for the image comparison?

Question

Hi team,

Most of our test cases are failing with minor difference with the image comparison with our reference UX and application. Is there any way to find out the tolerance value of difference between the screen shots ? Kindly help.

Thanks,

Thushar

Answer 1

Hello Thushar,
Within the test framework, the screen comparison has a tollerance of 30 between the sum of each color channels two different pixel. As soon as the difference is higher, the test is treated as failed and a diff file is created, marking the corresponding pixels.
When you compare the two screenshots, also take into account the alpha value of the pixels.

With kind regards,
Rudolf

Comments

Hi Rudolf,

Thank you for your response. Could you please let me know where I can find the tolerance value in the Test Framework. Can I increase the value to more thane 30 for testing purpose. Kindly let me know the steps for the same.

Thanks,

Thushar

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Hi Thushar,
within the current test framework the tolerance level is fix. It was designed to cover possible tolerances between prototyper and Windows platform package.
In the next release of the test framework the tolerance is already adjustable as well as we introduce exclusion areas for the screen comparison. This release will come soon.

With kind regards,
Rudolf

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Thank you Rudolf.