Histogram Viewer is a Firefox extension designed for web developers and IT professionals to analyze images effectively. This tool allows users to generate a histogram of a selected image directly from the context menu by right-clicking on the image and selecting the 'Show Histogram of Image' option. The extension presents a new window that displays the histogram, which by default, combines all three RGB color channels. Users can also view histograms for each color channel individually, providing detailed insights into the color composition of the image.

In addition to histogram generation, Histogram Viewer offers a grayscale histogram feature with customizable calculation methods, allowing users to weigh color channels based on human perception. The extension also presents various statistics, including minimum, maximum, mean, and median values, which can be optionally hidden. As users interact with the histogram, they can see individual values and their occurrences, enhancing the tool's usability for precise image analysis.