tiff files
TIFF has the advantage of higher quality due to the absence of compression artifacts, but JPEGs saved with low compression (Photoshop's level 10 or better) will not have detectable artifacts. TIFF files and low-compression JPEG files may be saved and resaved without image deterioration, but saving and re-saving a high-compression JPEG file will degrade image quality.
TIFF files can also have greater bit depth, which makes them better candidates for significant pixel-level editing, such as color and tone adjustment. However, a TIFF file is at least five times larger than even the least-compressed JPEG version of the same image, or 10 times larger in 16-bit mode. This means TIFF files will take up five to 10 times more storage space when archived or written to removable media for delivery. They will also require five to 10 times the bandwidth or transmission time to send electronically. TIFF files do have several compression options: LZW, ZIP, and JPEG. Since TIFF compression is not universally supported, it is important to communicate which compression method you intend to use with the receiver of the files. In general, once an image has image processing and correction by a skilled photographer or digital imaging specialist, there is little advantage to requesting or delivering 16-bit files unless the end user plans to make significant creative tonal or color edits to the image.
There is also a peculiarity with saving TIFF files: The option to save using PC byte order or Macintosh byte order. The TIFF specifications require all applications to read either byte order, so either option is correct.
jpeg files
JPEG offers smaller sizes due to the format's sliding compression scale. But JPEG uses "lossy" compression algorithms that toss out some data. As the compression level increases, so does the amount of "lost" data, decreasing both image quality and file size. The trade-off is more compression artifacts with more compression in order to achieve smaller file sizes. Although Photoshop's JPEG quality level 8 is the minimum recommended value, a setting of 10 to 12 is preferred. Other programs have different compression scales, so test to determine the corresponding settings. For instance, Microsoft Expression Media (formerly iView Media Pro) offers a JPEG setting of "high" that is roughly equivalent to Photoshop's setting of 10.
Remember: Uncompressed TIFF files without generating any artifacts. JPEG files may be saved and resaved several times at level 12 without obvious image deterioration, but saving and re-saving a high-compression JPEG files will degrade image quality.
Other potential drawbacks to the JPEG format are its maximum 8-bit color depth, compared to TIFF's 16-bit limit. JPEG image files also cannot include layers or alpha channels.
For most people, most of the time, the JPEG format will be easier to work with than TIFF. With proper handling, a JPEG image at quality 12 would appear equal to a TIFF, except the latter can include a greater bit depth, layers and channels. Stock-image distributors can choose between JPEG and TIFF, depending on their client base and preferred method of delivery. Because stock distributors now focus on electronic delivery, JPEG files are likely the best choice. With sufficient infrastructure, stock distributors could maintain both formats: a TIFF original, and a method to make JPEG copies as needed.
tiff and jpeg at a glance:
| TIFF | Standard JPEG |
| Uncompressed format (except TIFF compressed) | Compressed format |
| No compression artifacts | Compression artifacts not usually visible at Photoshop quality 10 and above. JPEGS saved at quality 12 are visually indistinguishable from TIFF. |
| Can be opened and saved without damage to the image | Re-compression takes place each time an image is resaved. Repeated saving of an image leads to deterioration. |
| Can be 16 bit, so better for image editing | Only 8 bit. Editing will cause more damage to the image. |
| Larger file. Use more storage space, but are standard for quality archiving. | Smaller file, Good for emailing, downloading, bulk storage of news images |
| Can include layers and alpha channels | Files are "flattened" and cannot include these |
raw files
When we speak of raw file delivery, we must carefully define terms. Some people consider as "raw" an unretouched or "out-of-camera" TIFF file. Actual raw files may be of two varieties: proprietary raw (such as .CR2, .NEF, .FFF and more than 100 others) or Adobe's DNG format. As a general principle, you should neither request nor deliver proprietary raw files. Proprietary raw files are by their very nature unprocessed. They may not convey the color, tone or other visual information the photographer intended to share. One imperfect solution would be including a Macbeth color checker or similar tool in every frame, or in a reference image created with the same lighting. Another way, also imperfect, would be for the photographer to adjust the color in raw-file processing software, and then specify the receiver use an identical version of the software to open the files. The photographer would need to carefully include reference data, such as XMP "sidecar" files from Adobe Camera Raw or the cached color settings folder from Phase One Capture One. Even when following these procedures, people requesting proprietary raw files need to understand they are, in effect, preventing the photographer from creating a finished product. There is also a risk of losing metadata, since in many cases, custom metadata identifying the creator, copyright information, status and usage terms is not embedded in a proprietary raw file, but is attached as a sidecar (usually XMP) file. A potential compromise might be requesting proprietary raw files AND TIFF or JPEG files processed by the photographer, offering a comparison to insure against inaccurate raw conversion.
dng files
Some standards bodies (DISC, for instance) list DNG as a possible delivery file format. Since DNG images are in a raw file format, they are also subject to interpretation. However, a DNG file does contain processing information, along with metadata and a rendered JPEG file. The rendered JPEG offers a visual representation of the photographer's processing. This JPEG can be viewed in Adobe Bridge, Photoshop or most cataloging software, such as Microsoft Expression Media. While DNG is a better delivery option than proprietary raw, it stills gives the receiver wide latitude to interpret the image. This can be a double-edged sword – good if the photographer has poor technique, and bad if the photographer has a processing style or finished look that is overridden by the end user.
jpeg 2000 (.jp2, .jpx, .jpf)
Created by the Joint Photographic Experts Group committee in 2000, JPEG2000 is a wavelet-based, image-compression standard. JPEG2000 offers a compression performance gain of around 20 percent compared to the standard JPEG. For lower or higher compression rates, the improvement can be somewhat greater. It has, however, notably higher computational and memory demands, which for most photographers means opening and closing JPEG2000 files takes more time. Unlike the standard, baseline JPEG, JPEG2000 does offer a fully lossless option. Improved compression options and performance, however, are not the main benefit of JPEG2000. The real achievement of JPEG2000 is "smart decoding." This feature enables a decoding application (or plug-in) to access and decode only the required portion of the code stream. This means a single JPEG2000 image can supply multiple, reduced-resolution versions of the original. These might include specific file sizes, and/or a high-quality, high-resolution view of a specific portion of the image. This makes JPEG2000 an excellent format if you require the ability to smoothly zoom, pan and rotate images. Creating compressed images that contain different quality levels allows master images in an archive to supply multiple derivatives, saving time and bandwidth. This makes an image archive much more efficient. In addition to this array of output options, JPEG2000 can handle very large images, at least up to a terabyte. JPEG2000, unlike standard, baseline JPEG, supports high-bit-depth (up to 16 bits per channel vs. 8 for standard JPEG) and high-dynamic-range images. JPEG2000 also underpins the MJ2 and JPM formats for motion images (each frame is a JPEG2000-compressed image) and compound images (images, graphics and text). These additional features make the JPEG2000 format a potentially valuable option for archiving film, video and historical materials.
JPEG2000 has not been widely adopted by photographers. Raw and DNG are viewed as better solutions for their specific needs. And JPEG2000 is not a good candidate to replace standard JPEG as a digital capture format, since the former requires far greater compression time. Still, photographers may want to become more familiar with JPEG2000 and be prepared to deliver in one of its variants, since many cultural heritage and digital preservation communities use it as the basis for their collections. Unlike photographers, these institutions are less concerned with improved rendering options over time. Their focus is preserving a specific rendering intent in the best way possible, with the most efficient storage and delivery options. JPEG2000 does these things well. The unanswered question is whether this "niche" adoption of JPEG2000 will ensure its long-term viability as an archival format. Some of the cultural institutions finding JPEG2000 to be the best current solution for their archiving needs include The Library of Congress, the Harvard University Library, Library and Archives Canada, Chronicling America website and the Google Library Project. For more information, see the Digital Preservation Coalition Technology Watch Report.
hd photo (jpeg xr)
Although this may become an important format in the future, especially if the JPEG Committee approves this as an additional JPEG standard, lack of native support in Photoshop CS3 means that requesting files in this format would be problematic. Originally called Windows Media Photo, then renamed HD Photo, Microsoft is now working with the Joint Photographic Experts Group to make the format a JPEG standard, JPEG XR (for extended dynamic range). HD Photo has shown no compelling advantages over JPEG2000 for archival purposes. But HD Photo does have a faster compression algorithm compared to standard JPEG, and this offers some potential advantages as a digital capture format. Since the main drawbacks to the standard JPEG format are the 8-bit tonal depth limit and limited dynamic range, JPEG XR could provide a welcome step. Covered by Microsoft's Open Specification Promise, JPEG XR avoids problems associated with proprietary raw formats. The future of JPEG XR depends on camera makers offering it as a capture format. If and when this happens, then JPEG XR would become a potential archival format as well.
HD Photo is also the basis for the Microsoft Seadragon project and the related Photosynth photo viewing technology. These new technologies could also drive the adoption of HD Photo, since they both use HD Photo's ability to decode only the needed portions of an image, allowing for rapid screen draws as images are combined, zoomed, and panned. The latest Windows operating systems include full support for HD Photo. Updated version of HD Photo Plug-ins are available from Bill Crow's HD Photo Blog http://blogs.msdn.com/billcrow/archive/2007/08/17/updated-hd-photo-plug-ins-for-adobe-photoshop-software.aspx
Although OS X doesn't currently support HD Photo as a native format, it is supported through installing the HD Photo Plug-ins for Adobe Photoshop CS2 and CS3. Whenever Photoshop writes an HD Photo file, it also creates a thumbnail on the resource fork in a compatible format for OS X. The result is that thumbnails are created that show in the OS X finder.