Image thumbnails are used in most imaging products and applications, where they allow quick preview of the content of
the underlying high resolution images. The question: "How would you best represent a high resolution original image
given a fixed number of thumbnail pixels?" is addressed using both automatically and manually generated thumbnails.
Automatically generated thumbnails that preserve the image quality of the high resolution originals are first reviewed and
subjectively evaluated. These thumbnails allow interactive identification of image quality, while simultaneously allowing
the viewer's knowledge to select desired subject matter. Images containing textures are, however, difficult for the automatic
algorithm. Textured images are further studied by using photo editing to manually generate representative thumbnails.
The automatic thumbnails are subjectively compared to standard (filter and subsample) thumbnails using clean, blurry,
noisy, and textured images. Results using twenty subjects find the automatic thumbnails more representative of their
originals for blurry images. In addition, as desired, there is little difference between the automatic and standard thumbnails
for clean images. The noise component improves the results for noisy images, but degrades the results for textured images.
Further studying textured images, the manual thumbnails were subjectively compared to standard thumbnails for four
images. Evaluation using forty judgments found a bimodal distribution for preference between the standard and the manual
thumbnails, with some observers preferring manual thumbnails and others preferring standard thumbnails.