What difference in image processing accounts for the visible difference between the following two images of the brain?

The visible difference between the two images of the brain can effectively be attributed to the window width (WW) setting used during image processing. Window width refers to the range of CT numbers (Hounsfield units) that are displayed as shades of gray. A narrower window width enhances the contrast of a specific range of tissues, emphasizing subtle differences in those tissues, while a wider window width provides a broader range of grays, resulting in less contrast but displaying more anatomical detail.

By adjusting the window width, radiologists can optimize images for specific diagnostic tasks. If one image has a broader window width, it can lead to a more generalized view of the anatomy, while a narrower window width focuses on specific tissues or conditions, enhancing their visual differentiation. This setting is crucial for diagnosing conditions within the brain, as it allows clinicians to observe the relevant structures and any potential abnormalities more clearly.

The other options, while relevant to CT image processing, do not directly account for the differences in how the image appears based on the contrast and structure specificity provided by adjusting the window width.