I would like to know what formats I shoud be saving image files in and what are the benifits of each of the formats-jpeg-giff-tiff-bmp.... or where can I find this info.

-- Rick BEebout (rickb@extremezone.com), November 11, 1998

Answers

Dennis Curtin's excellent "short course" in digital photography has a section in it somewhere on file formats. You'll find his site at http://www.shortcourses.com/

For myself, I use JPEG at a low compression/high quality ratio. The results look good, and you save 3-5x on disk space. (Just don't get carried away with the compression ratio though!) GIF is really designed to handle screen graphics like menus, etc the best, isn't good for photos. TIFF and BMP are pretty equivalent - uncompressed formats, with full color capabilities. TIFF is a bit more universal between applications, and between the Mac and PC.

-- Dave Etchells (web@imaging-resource.com), November 11, 1998.

First off, you can ignore GIF for any photographic data. BMP and TIFF are pretty much equivalent technology, but TIFF (or more accurately, a subset of the TIFF standard) is a more widely supported format . JPEG gives you the best size/quality tradeoff for photographic imagry, but you do acutally lose some information when saving as a JPEG, so you should avoid it as an intermediate format. Use JPEG to archive completed work, and only if you don't expect to edit it again.

However, having said all that, the real answer when working with digital cameras is to save whatever image comes directly out of the camera. You will never get any MORE data/quality than that. For most consumer digital cameras this is JPEG. Converting that JPEG to a TIF doesn't do anything but make the image larger -- it can't add data or improve the image. For Olympus cameras and the camedia software, this means leaving all quality/size/format options unchecked, so that you download the JPEG images directly from the camera. With any camera and a flash adapter, you should save the images exactly as they come off the flash memory. Consider this file the "negative". As long as you keep it you can always get back to the original camera image, even later when you decide that you no longer like the effect of "auto levels" on all of your images...

-- Ben Jackson (ben@ben.com), November 13, 1998.

Just adding my own two-cents; sorry I missed this post before. To add to Mr. Etchells' and Mr. Jackson's replies, I thought I'd reiterate the importance of NEVER re-saving a JPEG. I've helped people with graphics editing, and consistently I've found that although they know and understand that JPEG is for archiving, in the excitement (or frustration) of editing an image, they instinctively hit "save" and irretrievably degrade their original image.

What I do and suggest, is to IMMEDIATELY save a virgin digital image to a lossless format (NOT JPEG) upon opening it. This retains the original and allows fearless freedom to play.

A few more thoughts on formats... most graphics programs offer the LZW compression option for TIFF, which greatly reduces size, though not as much as JPEG. The beauty here is that this is lossless compression, TIFF is a very universal format, and if you use color management, it can store color space information (as does JPEG). TIFF and JPEG are also able to store file information such as captions, copyright, etc. BMP is useless on all counts. Although there is sometimes an option to save BMPs with RLE lossless compression, I find few programs bother to support it. Keep in mind that if you use software that supports layers like Photoshop or Paint Shop Pro, then you must use their proprietary formats (PSD and PSP, respectively) unless you decide to irretrievably flatten your image.

-- Jeff Jacques (jjazzy7@rocketmail.com), December 09, 1998.