How does automated visual testing differ from manual visual testing?

Automated visual testing is characterized by its reliance on specialized tools that systematically compare images to identify visual discrepancies, whereas manual visual testing depends on the human ability to observe and detect visual defects. This fundamental difference allows automated testing to efficiently analyze large sets of images or web pages, detecting changes that may be missed by the human eye during a manual inspection. Moreover, automated testing can execute these comparisons consistently without fatigue, improving reliability and repeatability in detecting visual regressions across various environments and screen sizes.

The use of tools in automated testing also allows for features like pixel-by-pixel comparison, achieving high precision and accuracy, which is particularly beneficial in environments with frequent updates or when multiple iterations of a product are being tested. This technological capability contrasts with the subjective nature of manual testing, where the outcome can vary based on the tester's experience and attention at the moment.