Systems and techniques to acquire image data. In general, in one implementation, the technique includes: acquiring image data for a plurality of areas of a scan region. The technique may further include processing the image data to determine whether an area includes one or more desired features. The technique may further include designating an area as “interesting” if it includes a desired feature, and designating an area as non-interesting if it does not include the desired feature. The areas may be sub-divided one or more times, and subdivisions may be analyzed to determine if they include a desired feature.