PDA

View Full Version : TIFF Format


ftlmo
2nd of October 2003 (Thu), 04:02
Ihave a canon s30 and use zoom browser a lot and started experimenting with RAW fORMAT i was just woundering that when i take the raw pic when i d l them should i save them as TIFF.If so what exactly is tiff and is it a good thing to use.

Ikinaa
2nd of October 2003 (Thu), 05:24
ftlmo wrote:
Ihave a canon s30 and use zoom browser a lot and started experimenting with RAW fORMAT i was just woundering that when i take the raw pic when i d l them should i save them as TIFF.If so what exactly is tiff and is it a good thing to use.

TIFF is a loss-less image format, it means, that unlike jpeg, the whole information of the picture is stored in the file, whereas jpeg compresses the picture and when opening it again, it recalculates the missing parts. (therefor jpeg is smaller than tiff).
Tiff can also be compressed, but without information-loss.
Tiff, like RAW is like your negative in film, whereas jpeg is perhaps as the paper-print
Check http://home.earthlink.net/%7Eritter/tiff/ for more information

stopbath
2nd of October 2003 (Thu), 09:44
TIFF and other lossless formats like PNG will compress the file by using exact calculations. These files will decompress to exactly the same quality as the original. A file saved 100 times will remain an exact copy of the first version.

Jpeg compresses by approximating. Given the level of compression and options, it will start approximating the photo into little blocks of data. At each save the file will be re-approximated. So if you save the file 100 times, the file will be re-evaluated 100 times. The resulting file will be of lower quality than the first.

Therefore, never save as jpeg until you need to. Try to always use TIFF, PNG or some other lossless format for every save you make during your edit process. Try to never edit the original camera file. Make a dup first for any editing.

I would really like to see a lossless JPEG format. A file saved in the format of jpeg, but without any compression added. It is verbatim unchanged. Perhaps there is a reason for it not existing, but I can't think of a reason.

Jerry Vanderberg
2nd of October 2003 (Thu), 09:51
How much of the loss from saving in JPEG just theoretical and how much is really visible to the eye on prints and with a monitor? I know that when you save to JPEG in PhotoShop Elements you have a choice in the quality of your saved image. When you use the highest quality to save, does it make a real difference in how the saved image will look?

stardis
2nd of October 2003 (Thu), 20:42
I have an s30. I use ZoomBrowser (it works perfectly) to download images from a card reader. I save them in a folder by the calendar month, the file 2003_09_29 goes in the September folder, and burn each month to a CD. You can then open that file as many times as you want and print that image and it will look FAR better than anything you can get from the photo lab.

If you want to post them on the web using PS Elements 2, you can use the the 'Save for the web' wizard at the default settings and the image will be indistinguishable from the original. It seems best to me to reduce the image size in that wizard to say 640 X 480 so that the image is smaller in size and more easily viewed by others; or even smaller if that seems more appropriate.

atkinson1
2nd of October 2003 (Thu), 22:12
I save them in a folder by the calendar month, the file 2003_09_29 goes in the September folder, and burn each month to a CD.

Yeah thats what I do too. Sometimes I will take heaps in a week, so I burn to CD after each shoot (cos you can add files to data CDs that are not already full) just incase they get deleted or something.

Then, like you also, I reduce them down to show people on the net, so the file sizes aren't too big.

stopbath
3rd of October 2003 (Fri), 08:31
Jerry Vanderberg wrote:
How much of the loss from saving in JPEG just theoretical and how much is really visible to the eye on prints and with a monitor? I know that when you save to JPEG in PhotoShop Elements you have a choice in the quality of your saved image. When you use the highest quality to save, does it make a real difference in how the saved image will look?
How much data loss is dependant on your settings. The stronger the compression the more the data is lost. Do some testing to see. Take a photo with good strong contrasting colours and strong lines and save several versions at different settings. Name each file so you can tell the settings. Compair the versions to each other and to the original. Without enlarging the files, most above 50-75% will look good. Under extreme enlargment, perhaps even the best won't look as good as the original.

75% is a general good starting point. You may find some shots need less compression though.