Roger, JPEG (.jpg, or .jpeg file extensions) are compressed files. That means the camera or software application throws away pixels of data that it deems not essential while still preserving the overall image. It is just like the days of cassette tapes or video tapes. When you make a copy, the sound quality or image quality goes down a bit. If you were to make copy of the copied tape, the quality gets even worse. Each time a JPEG file is saved, a bit more of the data is lost. When you send a JPEG to the publisher and he or she has to crop it and again save the new file to a JPEG file format, the image quality degrades. Do this a few times and the image is not worthy of publishing. Most image manipulation software applications will let you select a compression ratio. I set mine to about 90% (i.e. the least compression) for JPEG images I post on my web sites.
TIFF (.tif, or .tiff file extensions) files are uncompressed file formats. You preserve the original data. Nothing is ever lost, unless you crop the image. As long as you have the original TIFF file, you can always go back and save it (using computer software) to a JPEG format for further distribution. Because of the fact that TIFF files preserve all data, those files can be quite large. This can, indeed, lock up a computer that doesn't have enough memory to handle the image file, plus all the other software that is normally running on a computer (you may also need to be patient, because it may just take time to load it into memory - during which the computer appears to be locked up). The RAW file format is specific to the camera. It is like TIFF in that it preserves the original camera's raw data for the picture. However, since the format is usually specific to the camera or camera manufacturer, you generally can't distribute it to have someone else be able to read that file. That's when you have to save the image to either a TIFF or JPEG format. If you have to e-mail someone an image file, you generally will want to save it to JPEG format (compressed files produce smaller file sizes). If you can send a publisher a CD that contains one or more photos, you can use the TIFF format. I would not send a TIFF file via e-mail, because some recipients' e-mail mailboxes may not have enough server space allocated to be able to store large files. I hope this helps, - Peter. On 10/22/2010 1:38 pm, Roger Nulton wrote: > Bob, > > I would like to see this discussion too. The issue of JPEG vs. TIFF is > confusing to me. I was sent some plans in TIFF a while back and they locked > up my computer when I tried to open them: it was not an antique computer > either<g>. When I save pics from my digital camera, they are identified as > JPG in the basic photo program that I like to use. They look pretty clear to > me, even when enlarged for cropping. > > Roger Nulton > > > From: shabbona_rr > Sent: Friday, October 22, 2010 7:49 AM > To: [email protected] > Subject: {S-Scale List} Re: Cameras > > > > OK, this is a technical question, and then I'll drop the subject because it > is only vaguely related to trains. > > Due to the discussion on this list, I took a 4.26 MB JPEG photo and saved it > as a TIF. According to the properties, the TIF is 26.1 MB. How did changing > the format raise the size of the photo to that degree? Also, I didn't really > see much difference in the quality of the photo in either format. > > I would really like to know these things, and study them the best I can, but > my comprehension is sometimes a little limited without some outside help. I > didn't know how hard it is to draw a straight line until I tried to do it > with a computer, and now I'm having the same problem with taking a picture. > > Bob, I attended your clinic in Duluth, and a lot of my questions all began to > come together, but to much time elapsed between then and when I got to try > the techniques you described. > > Offline responses welcome to save the list for more important things, like > '56 Fords (with Overdrive, I might add), '73 Mustangs, and DCC, etc. :<) > > Bob Nicholson ______________________________________________ > > --- In [email protected], Bob Werre<b...@...> wrote: >> Chris is stating basically the same information that I've been giving at >> my various clinics at the NASG conventions. I was told when I attended >> an imging seminar once that a JEPG is created by the camera's onboard >> computer. This itty bitty computer takes the raw data and compresses it >> the best it can, whereas if you shoot in RAW you now have everything >> that the camera can produce. Then your larger full blown computer does >> the rest of the work with your 'abiliities' controling the computer. >> >> Chris also mentions that he likes to be able to crop and recompose the >> image because it will help his design. For the last 35 years they've >> always told me to shoot 'loose' so they can do just that. So if you >> have a 4 mp camera you'll have to shoot a little tighter (thus giving >> the designer fewer choices) or reproduce the final image a bit smaller. >> On the other hand some of the most recent camera offerings will provide >> an excess of information that most pros really don't need. So don't be >> fooled when someone says they shooting with a 90 mp camera and only >> using it for magazine usage where a 10-16 mp will do just fine. The >> problem comes up when you have to store all those very large images and >> ever more powerful computers to push those pixels around. The >> computer, software and camera folks have to sell new stuff to you and me. >> >> Bob Werre >> BobWphoto.com >> >> >> >> Christopher Borgmeyer wrote: >> >>> >>> >>> Finally a technical bugaboo. JPEGs are lossy. That means they loose >>> data and introduce noise. Even at 100% quality. TIFFs and RAW files do >>> not. If you have the option, shoot in TIFF or RAW. If you must shoot a >>> JPEG make sure it is the highest quality setting you can shoot. And >>> never save a file over and over again as a JPEG. Each time you run >>> that JPEG compression algorithm on an image you introduce more and >>> more noise. Trust me, with todays monitors all those jaggies will be >>> spotted. We know where to look to spot the little rascals. If you're >>> editing your shot in Photoshop, for example, save the shot as a PSD or >>> some non-lossy format as you work. Maintain the quality of the data. >>> JPEGs are the enemy. >>> >>> The moral of all this, composition and quality will always catch the >>> art director's eye. >>> >>> Chris Borgmeyer >>> >>> >>> >> >> >> >> [Non-text portions of this message have been removed] >> > > > > > [Non-text portions of this message have been removed] > > > > ------------------------------------ > > Yahoo! Groups Links > > > > -- Peter Vanvliet ([email protected], or [email protected]) Houston, Texas "It is easy to give up; anyone can do that..." http://pmrr.org/ (my model railroad) http://fourthray.com/ (my company) http://houstonsgaugers.org/ (model railroad club) -- ------------------------------------ Yahoo! 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