Techniques and tools for analyzing and adjusting the exposure of digital
images are described. For example, a computer processes a digital image
by analyzing exposure data, assigning an image classification (e.g.,
StretchNeeded, UnderExposed, OverExposed, or Normal) based on the
analysis, and selecting an exposure compensation technique (e.g.,
histogram stretch, positive gamma curve, negative gamma curve, or no
adjustment) based on the image classification. The exposure data can be
luminance values for pixels in the digital image represented in a
histogram. The computer can produce transform data comprising a
transformation of the exposure data according to the selected exposure
compensation technique. The computer can store transform data in a
look-up table and can store the look-up table in the digital image file.
The described techniques and tools can be implemented as a feature of an
operating system environment and can be activated responsive to user
action via a user interface.