From: "Llorenç Herrera Aznar" <lha@xxxxxxxxxxxxx> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@xxxxxxxxxxxxxxxxxxxxxx> Sent: Thursday, September 16, 2004 1:14 Subject: RE: That old jpg v. RAW argument again... > This is my first message in this list, I've been reading you for a while and > now I decided to write. First of all, excuse me for my english, wich is > sometimes far from being "readable". your english is fine :-) > What Gary Lawton says about JPG versus TIFF is completely correct. Every > image saved in JPG format loses information about its detail, even it's > saved at the maximum quality. I don't think anyone here would actually work an image as a jpeg, the idea that it looses data everytime it's recomressed is well understood by most image workers these days - almost everyone who manipulates images who have obtained the original as a jpeg will save it to a TIF, PNG or some other lossless format. <clipped> > The fact is that the real application for 16bit/channel images (except for > some rare applications), is for, as I said above, digital retouching. With > 16bit/channel the digital retouching algorythms has a lot more information > to work with, and specially when you are working on black and white images, > 16bit/channel will be very useful on conversions, and the feared "histogram > gaps" will be very rare. just a point regarding the histogram gaps - the histogram tool is a small graphical representation in Photoshop that is only 128 pixels wide on the screen and while 8 bit images will show gaps in theat graph more readily than 16 bit images, a larger graph will show that many 16 bit images which appear to have no gaps in the photoshop histogram to actually DO have gaps, they're just not represented on such a small graph. > > I can talk more about histogram gaps and 16bit/channel treatment on black > and white images, if you find it interesting. > > I wrote an article specifically about this, wich is online here: > > http://www.fotopunto.com/?a=articles&aa=view&article_id=20 > > I'm sorry, the article is written in spanish. I'll have to learn Spanish! :-) karl
