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Photography Question 
Dede Carver

member since: 10/6/2002
 

Explain TIFF, JPEG and PSD


Would someone mind explaining in simple terms the how's, when's and why's of TIFF, JPEG, and PSD? I am just getting the hang of digital photography. There seems to be sooo many different terms and ways of doing things it gets confusing.
At this point I take the shots, come home and upload them to a file as originals and always save them in JPEG. I then burn this to a CD as originals in the JPEG form. When I can go back, I reopen the folder, mess with the files in PS6 and resave in JPEG form, then burn again to a CD for printing.
I just read something that said, "JPEG compression is perfect transient files for sending to the lab for printing, but avoid using the compression as a working file type." This is exactly what I have been doing.
So can someone give me the exact step by step details for uploading, saving, working in PS, then saving, and finally printing? Also, is there a difference in how a file should be saved when prints are uploaded to a lab vs. copied to CD and taken to a lab?
Thanks so much for anyone's help!!!

9/5/2004 10:12:40 AM

 
Gregory LaGrange
BetterPhoto Member
gregorylagrange.org

member since: 11/11/2003
  TIFF is an uncompressed file. If you have a original JPEG, and you plan on doing a lot of Photoshop stuff, it's best to save the JPEG when you first download it as a TIFF. So each time you resave after you've done something to it, you don't lose anything.

JPEG is compressed, and can be different levels of compression. If you shoot the original as JPEG, it's fine to save as the highest level of JPEG. Minor changes with Photoshop won't effect the quality (such as lighten or darken, then saving). However, you don't gain anything if you have JPEG saved on hard drive, then change it to TIFF. But it is best if you're going to do cut/paste, lots of filter effects, drastic color changes, even if it's shot JPEG, to (right after download) first save it as TIFF.

PSD is a Photoshop format that when you open it, it will activate Photoshop if it's on your computer. (And if you're wondering, you can put a PSD-saved image on a computer and instantly get Photoshop.) It saves layers for unflattened images if you haven't finished doing whatever to it. It allows you to embed captions in the file (not meaning visible in the image) and any other info you might need.

9/5/2004 2:13:00 PM

 
Karl P

member since: 7/15/2004
  Greg said: (And if you're wondering, you can put a PSD-saved image on a computer and instantly get Photoshop.)

Don't know where you got this info from, but it's misleading. Having a certain type of file on your system does not get you access to the program that made it.

To the original question, here's what I do. All images from my digicam are saved as JPG. I edit in PSCS and save any of those in PSD format so that I can preserve any correction layers. (You could use TIFF also as it supports layers.) This allows me to go back and re-edit without losing what I've done already. I can tweak or change what I've previously done. I also know by looking at the files in a folder which are original and which are edited.
Be sure you're working in sRGB color space through all your edits in PS. Your digicam files are sRGB (most likely) and printers want sRGB.

9/7/2004 6:55:39 AM

 
Dan Durfey

member since: 4/15/2004
  Is PSD format lossless like Tiff?

9/7/2004 11:07:49 AM

 
Gregory LaGrange
BetterPhoto Member
gregorylagrange.org

member since: 11/11/2003
  Simple typo.
Lost connection in the middle of typing.
Meant to say you can't put a pSD-saved image on a computer and instantly get photoshop.
You have to have photoshop on your computer in order to open a psd-saved file.

9/7/2004 2:52:46 PM

 
Michael Kaplan

member since: 5/27/2003
  Yes, PSD is a Lossless format like TIF.

There are many formats available (too many imo) but the ones you mentioned are the most known as well as GIF & BMP and maybe the odd other for Mac. JPG is a Lossy format. What that means is that when JPG compresses a file, it does so partially by losing some of the information in the file. The amount of loss depends on what compression level you use. The higher the compression, the more data that is lost. Compression is similar to using ZIP to compress files on a computer BUT ZIP is Lossless. When you open up a zip and put the file back on the hard drive, it is exactly as it was. You can easily see JPG compression artefacts in smooth objects like skies where you stop seeing the smooth transactions in shades and start seeing some digital manipulations.

When you first save in a JPG from your camera, if you are using best quality, you are not losing a lot of data and for some the compression won't be noticeable at all. When you take that picture and edit it and resave, you are again losing more data. Each time you reload and resave a picture you lose more and more. You can easily try this to see by opening up a picture in any photo editing program, save it under a new name (ex:saved2.jpg) and exit the photo. Open saved2.jpg and resave it again under a new name (saved3.jpg). Do the same thing again and again and then after a few times look at each picture and you can see the quality going down from one file to the next.

That is why Gregory said to save as a TIF. This will allow you to save as many times as you like without losing any more quality than was already lost in the original file. This is also why many people like to save the file in RAW format (in some PnS & DSLR cameras that offer the option) so that there is no loss at all (except for Nikon camera(s) that do lose some like the D70 but still much better than JPG).

The downside of course is that the TIF is a much larger file. As an example, on my old Canon 10D, a 6.3 MP camera, the CRW (Canon RAW) was about 5.6MB. The JPG was about 2.2MB. If saved as an 8 bit TIF, the file size was 18MB and if saves as a 16 bit (the camera actually uses 12bits), the TIF would be a whopping 32MB file.

PSD is a native Photoshop file and is lossless like the TIF. It is more ideal to use for editing a file and can be smaller than a TIF because PS has the ability to compress with Lossless compression LZH or ZIP which is not as widlt supported by other programs than uncompressed PSD. Like Gregory mentioned, if you use Photoshop, by double clicking on a PSD it will automatically open the file in Photoshop (whether Elements or regular) and keeps all the layers you may have created. It is perfectly fine if you go from in camera JPG to PSD and then leave it as a PDS, save it as a TIF or even JPG if that is what your requirements are. I like to convert from RAW to TIF, Edit and then save the edited in PSD and then if going to web I make a final save in JPG. This allows me to know on any given picture what has been done. If I see a PSD, I know it is an edited photo. A TIF is a final, RAW my Digital Negative and JPG my web or viewing copy

As long as you keep your original file, you can always reproduce the picture by re-editing it so that out of camera picture is your digital negative. For the best end result, all editing should be done and saves as TIF or PSD (or whatever editing program you use) and then you will not be losing information each time you save.

I hope this helps.
Michael Kaplan
Canon EOS-20D
http://www.pbase.com/mkaplan

9/17/2004 9:30:05 AM

 
Dede Carver

member since: 10/6/2002
  Thanks for everyone's help in explaining this to me. Just one more quick question. I like to save a hard copy of the originals on disk and then another after I have played in Photoshop. Can this be done in a TIFF or PSD or will the files be to big for the originals? The PS copy I usually take to a local lab for developing. This would be best done in JPEG right?
Thanks again. DeDe

9/19/2004 9:59:00 AM

 
Michael Kaplan

member since: 5/27/2003
  Absolutely, you can save as TIF or PSD. I save my RAW as my negative and then the TIF, PSD or JPG's I create with the RAW of course being the most important. I usually save all my RAW together and others separately so I have multiple disks as backup.

And btw, a good thing to do is to use the verify option of your burning program so that you can verify that the CD/DVD you make is good before you delete the files off your camera/hard drive and lose them forever.
Michael

9/20/2004 4:15:12 AM

 

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