What should be considered when defining baseline images for visual testing?

When defining baseline images for visual testing, consistency in the environment and expected application state is paramount because it ensures that the conditions under which the images were captured remain uniform throughout the testing process. This consistency helps in providing reliable comparisons when visual diffs are analyzed. If the environment changes or the application state varies, it could introduce visual discrepancies that may mislead testers into believing that there are actual defects in the application when, in reality, the differences are due to external factors rather than a change in the application itself.

The other considerations mentioned, such as quality and resolution of the images or the cost of storage, are important but secondary to the core principle of consistency. A high-quality image captured under varying conditions may not provide accurate test results, and while cost is a practical concern, it doesn't influence the reliability of the visual testing process as directly as the consistency of the testing environment does. Similarly, accuracy and speed of image capture, while relevant to the testing process, do not adequately address the foundational need for a stable baseline image under controlled conditions. Thus, focusing on the environment and expected state is crucial for effective visual testing.