It was 2/8/03 5:17 pm, when Paul Tansley wrote:
> You are shooting your camera files as [jpg], fine, no problem there, as far
> as I'm concerned. It would be marvellous if we could all shoot RAW, but its
> not always possible, and not always necessary. The amount of loss caused by
> the original compression (jpg-ing) is fairly minimal, and almost certainly
> invisible to the human eye, though I'm sure many will disagree with this,
> its a fact.
Paul
One big advantage in shooting in RAW format is you can set the color
temperature at a later date if you have been shooting in changing light
(yes, I know you know that). If shooting in a studio with set lights, this
may not be such a big advantage. The exposure can be pushed a little further
and colors tweaked in 16-bit/Channel mode so that the file doesn't fall
apart as quickly as the JPEG does. Also, it's almost certain that the RAW
processors will improve over time so you hedge your bets by outputting as
RAW for future iterations of the file.
> Next you open up the file in Photoshop (personally I do a
> lossless rotation in Graphic Converter before this, as all my stuff is shot
> vertically. In case anyone is not aware, you can rotate a JPG without saving
> it, using certain software, you cannot however, open it in PS, rotate it and
> save it, that will degrade your image).
Is this an old wives tale? <G> Save a JPEG from a RAW or take a camera
originated high quality JPEG. Dupe it. Rotate one in GC or iView (I have
iView and not GC). Rotate the other in Photoshop (save it at 100% quality if
you want to and close it and then open it again). Put the two on top of each
other and change the blend mode to Difference. There may be the odd pixel
value changed but if you can see a *marked* difference at 100%, or even
400%, I'd be very surprised. It certainly is not going to print.
If you are outputting your files as JPEGs from your camera and you accept
that quality, the change is so minimal as to be negligible. So, I wouldn't
go as far as to say Photoshop will "degrade" your image when it rotates a
JPEG. It does change the value of some pixels but certainly not degrade the
image when judged visually. In fact, if you compare a losslessly rotated
JPEG and the RAW it came from, you will see a similar difference.
> Think of it this way. A jpg file produced by your camera is your "negative"
> once it leaves the camera and arrives on your computer, do not touch it ever
> again.
Well, it's not a negative in the traditional sense of the word. It's already
been processed by your camera once. The RAW file format comes closest to
fitting the description of a digital negative.
> PS - RAW v JPG - as I pointed out on another list recently. RAW is better
> than JPG, it contains more original data. However this does not mean that
> everyone needs to shoot RAW files. In an ideal world they would. But the
> world is not ideal, just yet and JPG files made on the camera and not
> resaved afterwards, will be absolutely fine for most peoples uses. As an
> example, I've shot magazines, A4 full bleed glossy magazines, with JPG files
> and I doubt if there was a single soul in the world, that could have spotted
> the difference, between my JPG's and a RAW file shot at the same time.
Try the same test with rotating a JPEG. See if anyone can spot the
difference between Photoshop rotated files and software that does "lossless
JPEG rotation." I think you may be pleasantly surprised.
--/ Shangara Singh
:: Adobe Certified Expert ~ Photoshop 7.0
:: Adobe Photoshop 7.0 Essential Tips
:: Exam Aids for Photoshop, Illustrator & Dreamweaver
:: Http://www.shangarasingh.com
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