Which is better for long-term digital image preservation: TIFF or JPEG or PNG images?
The Still Image Working Group within the Federal Agencies Digitization Guidelines Initiative (FADGI) recently posted a comparison of a few selected digital file formats. These are sometimes called target formats: they are the output format that you reformat to. In this case, the article compares formats suitable for the digitization of historical and cultural materials that can be reproduced as still images, such as books and periodicals, maps, and photographic prints and negatives.
The report is available in two parts. The first article at http://goo.gl/ZeBuQa provides background information and describes the tried-and-true uncompressed TIFF format. The second article at http://goo.gl/Ch5d8y describes the advantages and disadvantages of JPEG-2000, and PNG.
You also might want to read Guidelines: File Format Comparison Projects from the same organization, available at http://goo.gl/yLZmlP.