Sorry for the lack of trimming in my reply. Its just that each reply is to a certain point and would be hard to follow otherwise.
On 4/8/03 8:38 am, "Shangara Singh" wrote: > As far as I can see, Photoshop does not "degrade" a JPEG when it rotates > anymore than an application capable of lossless rotation. You can test it: > make a RAW file, make two JPEGs from it, rotate one using "lossless > rotation," use Photoshop to rotate the other, compare them with the RAW > output in Photoshop. Alternatively, make copies of a JPEG output by your > camera and rotate them and compare with the original. I haven't been > listening to the "lossless rotation" user groups and am basing my findings > on the above test method - if it's flawed, please point out the flaws or > supply a less flawed way of testing for degradation caused by Photoshop when > rotating and saving a JPEG. Shangara, I really have no interest in whether PS can rotate a JPG losslessly or not. I have no need of that function. You keep saying that PS does not "degrade" the image and yet later on you say that it does, but that no human can spot that degradation. I fully appreciate that, and appreciate what you are trying to say. However please appreciate what I am saying. Given the choice of rotating 100% lossless (in GC) or rotating 99.9999999999999 recurring losselessly in PS, I'm going to choose GC. And as pointed out before, I choose GC, mainly because its easier, rather than any other reason. I've tried most other apps that do lossless rotation, and I don't like them. I like GC. BTW, you say you do not have a copy, do you realise that it is shareware (or used to be, as far as I remember) and you can download a copy to try out. It is also one of the finest image browsers out there and am surprised that any mac user has not tried it for this function alone. Fair enough if you decide you don't like it, but there's no harm in trying it. I've always felt that its name (Graphic Converter) is a little misleading as I've never actually used it to convert an image. > BTW, iView takes 163 secs to do a lossless rotation on a 3.3MB JPEG and it > takes a couple of seconds to rotate the thumbnail in Photoshop's file > browser and then 2-3 seconds to open and rotate the file and another couple > of seconds to save the file. I rarely (read never) rotate one file, and I must say 163 seconds to rotate one 3.3MB file seems horrendous. Are you sure you've not made a typo there? I am usually rotating a shot consisting of 50-100 frames, jpgs of a 10d, so each is around 1.3Mb (high jpg). PS - While iView is quite a good browser. I personally do not like it. I have no need of its functionality and find sorting hundreds of files using it clumsy beyond belief. Graphic Converter's browser is far better in many respects (though different users will appreciate different functionality). For image sorting (same shot, different frames) the best mac program out there is PhotoGridX, which knocks the socks of anything else available. > A JPEG output from a camera, IMO, is akin to a print from a neg. OTOH, a RAW > output from a camera is akin to a neg because you cannot output an image > from it till you process it (if you want to be pedantic, call it an > unprocessed neg), and you can process it in many ways (as you can print many > versions from one neg), unlike a JPEG, which would be akin to scanning a > print and then processing that if you (meaning one) needs to repurpose it. > That's how I understand it and no amount of persuasion will make me think > otherwise. <g> Yourself and William seem a little confused on this matter. Not in your opinions, which you are welcome to have, but in what mine is. I have no interest in what anyone wants to call a negative/raw file/jpg/original/print etc. etc. I really don't, I'm not a teacher or lecturer and never want to be one. I know what they are, I'll call them what I like, that's all I care about. In my original post I merely used the term negative to explain to Stephen what he was doing with his JPG's by resaving them. I used the term because I thought he would understand it. I think he did! I in no way intended to start a thread on the "correct" dictionary terminology of the work "negative". I hope you don't take that as me being rude, I'm really not. Its just that posts like Williams, where he says "I thought Shangara's reference to a RAW file as a negative was very valuable" and "Personally I would prefer that this was not devalued by applying the negative analogy to all digital capture" referring to my previous post, really annoying. Its as if I was trying to write the rules of digital photography. I wasn't. As I said, I know what the difference is, I don't need to learn what a RAW file is or isn't, I've been there and done that, that was 3 years ago, I've moved on since then. I used the term negative merely to get over a point, nothing else. > As for your workflow, I did say that you (meaning you and/or one) may not > find any advantage in shooting RAW but if you find the "degradation" caused > by outputting a JPEG acceptable as opposed to a RAW output (while in your > workflow JPEGs may not be seen as degraded images, in other workflows they > can be when compared to the advantages of shooting in RAW), then the > "degradation" caused by rotating in Photoshop should be negligible too and > so Photoshop not labelled as an application that "degrades" images. I'm not > trying to convert you. Just putting the opposite POV, and trying to defend > Photoshop. If you feel the need to defend PS, by all means go ahead. But the fact is plain and simple AFAIK, that PS "cannot" do a lossless rotation (on a JPG) and resave as a JPG. It can do something so close that "no human alive" will ever notice, but it CANNOT do it losslessly (100% lossless, not 99.999% recurring). As far as I can see, I still have no need to rotate JPG's in PS. If someone want to (I'm sure there is someone out there) apparently its OK, because you won't ever see the difference. Fair enough, I accept that. But I don't want to, and that's not just because I'm a stubborn git, its because I don't need to use that function. And even if I did, I could save as a PSD/TIFF and get a 100% lossless rotation as opposed to a 99.99999% lossless rotation). PS - Why can photoshop not do a 100% lossless rotation. Since it can't be that hard, as other software manages it? > To degrade an image, the change must be noticeable and for the worse. I think you'll find that's your own definition of the word degrade. Again, I'm not interested in writing dictionary terms. As far as I am concerned it degrades the image. Whether the degradation is .0000000001% or 1% is not really of interest to me. Why? Because I can do the same function, quicker, using a third party piece of software. Without ANY degradation. > My view is you *can* open a JPEG in Photoshop, rotate it and save it and > open it again and the "degradation" is no more than what you are accepting > now by shooting JPEGs as opposed to RAWs. As I've said over and over, "So what?" I don't need to perform that function in PS. I can perform it 100% losslessly in GC much quicker. > When I say degradation, I'm not implying that you are accepting inferior > quality (there's always a trade off between quality and speed). I mean it in > the sense that it's possible to demonstrate degradation by outputting the same > image in RAW and JPEG and doing 16-bit color correction on the RAW and 8-bit > correction on the JPEG. No prize for guessing which will "degrade" first. I am sure that you are correct on this point, but have no interest in it either way. > However, if your color balance and exposures are perfect, the degradation will > be hard to demonstrate but not impossible, just depends how far you want to > take the file from the "original" capture. I never stray far from my original capture, my skill is mainly in my lighting and composition, not in my Photoshop Skills, I leave that to others :-) You seem to be arguing a point that I have no interest in. I've no interest in how much the degradation might or might no be in varying circumstances. Once that "original" file leaves my camera, I will try my utmost not to degrade it any further than it has already been by the initial JPG compression the camera gave it. Why is that so hard for you to understand? I'm not saying everyone else has to work the way I do. They can use whatever workflow they want, I merely try and tell people mine, so that they can make an informed choice as to the possibilities open to them, nothing else. > Also, by rotating in GC, you may produce truly lossless rotation but, as I > said, I don't have that application. So, if you can do the above test and > post your findings, it would be very helpful to the discussion. Which test exactly? Firstly, you could download GC from http://www.lemkesoft.de/en/graphcon.htm or version tracker it is shareware. And I seem to remember gives a fully functional demo. This would also mean the test could be run on the same hardware. If you want to send me some kind of test file, that would also be fine, I'll let you know how fast GC runs on my various machines. > Just to be clear, I'm not slamming the JPEG format. I've said many, many > times on this list and others that archiving or sending a file as a full > quality JPEG as opposed to a TIFF is perfectly OK and acceptable *if* space > or speed is a concern. If it's not, save as a PSD or TIFF. I'm not slamming RAW either, as I said originally. There is a time and place for shooting RAW and same goes for JPG. The choices you/one should make after that original capture, should be informed ones. I personally consider myself, informed enough to make those decisions. Given a clear choice of 100% lossless actions or "near as dammit" lossless rotations, I will choose whichever is easiest for me to perform. As the 100% lossless is easiest, I'll choose that for the time being. regards Paul -- Paul Tansley Fashion & Beauty Photography London +44 (0) 7973 669584 http://www.paultansley.com =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
