General photo editing questions

[LayzrHed]

Hi everyone (my first post by the way :) ). I'm very new to digital photography, so please forgive me if these questions are real basic. Any answers would be most appreciated.

Q1) When I rotate a jpeg image from portrait to landscape or the other way (i.e. a 90 degree rotation), is the image resampled or are the pixels transformed with no loss of data? (e.g. if I repeatedly rotated a jpeg by 90 degrees and then saved, would the final image still be identical to the original other than perhaps an orientation change?).
... I fear loosing quality from my master files if I rotate them; and hence browsing my photos can be rather tedious!

Q2a) What image file formats do you guys use when editing, or do you tend to just use whatever format is native to the program your using?

Q2b) I don't have Photoshop but sometimes I want to do basic editing without loosing image quality through jpeg resampling, and I read somewhere that some people convert their jpegs to tiff. Does anyone here use tiff?

Q3a) What software do people use to edit or remove EXIF data?

Q3b) I can't think why I would want to do this but... is it possible to append EXIF data, that may or may not be the original EXIF, to an image file that's had it's EXIF previously removed?

Q3c) Why do many people remove the EXIF from photos they put online?

Q4) If anyone here use the GIMP (http://www.gimp.org/) image editing program what are your thoughts about it?



LayZrHed

[the boss]

Welcome,

Your workflow should be burn first, then fart around. As soon as you rotate a photo, you destroy the image, you lose pixels, hence you have less to work with. If you rotate even once, it won't be the same quality as original.

I shoot RAW for everything, from candids to screaming babies. If you shoot jpg, YES! convert to TIFF and work on that. When I don't shoot raw, I always convert to 16mb tiff

I use Arles Image creator, or you can chose not to in photoshop.

Yes you can append data in photoshop. Many professional photograpehrs do that.

most don't knwo they're doing it but once you save for web, its gone or by using something to create webpages or auto resize, it usually wipes that info out.



Last two I didn't answer cause I dont know anything about them.

[Rogue Trooper]

A3c.) It's like a fingerprint with cam serial number and such. Depends if you fear to get identified or not. I don't.


P³

I just tried this out, even the normal save as jpeg in PS after editing removes the Camera maker notes part of EXIF info, including serial number.

Save for web removes everything just as Boss told us.

[toBot]

Boss, regarding rotation, I like your conservative approach to preserving the original images, and for pro shooting it's probably the best approach because it's foolproof. A friend of mine who is a wedding photographer likes to use 512MB compact flash memory just because the first thing he does after the job is to copy each card to its own CD first thing.

But from what I understand this problem depends on the software used; sw such as ACDsee provide lossless rotation. (I assume Photoshop does too). As a user of ACDsee for routine browsing/file management, I can report it even has a checkbox in the rotation tool box for "force lossless rotation".

Using this, I've carefully inspected the before/after rotation images and the file sizes are almost identical, and even at 100% I see no degredation in the image quality. EXIF data is also preserved. So now I routinely rotate as necessary and then save, it's made archiving and browsing a lot more streamlined for me and saves a lot of disk space.


This link has a bunch of jpg info, the loss has to do with the pixel block size and jpg dimensions:
http://graphicssoft.about.com/cs/digitalimaging/f/rotatequality.htm

and it has a link to a pile of editors claiming lossless rotation too:

http://graphicssoft.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=graphicssoft&zu=http%3A%2F%2Fsylvana.net%2Fjpegcrop%2Flosslessa pps.html

[LayzrHed]

Thanks everyone for your replies.

A2.) I personally use 1200 x 1600 px - but that's not 2:3 which would be 1200 x 1800 px
I'd be interested to know why you use that dimension?

In fact I've been wondering if I might find particular dimensions that would feel "intuitive" for particular types of shots. I don't think I'm experienced enough to decide upon this, but I suppose factors will include the type of composition (e.g. is the focus on her ass ;) or her face!) and my feelings about the subject. So when I something isn't screwed up and I'm cropping out of choice, I thought it might be useful to have some kind of "logical basis" :wacko: for deciding the dimension. I'm thinking either:
1) Crop to match a common desktop size, most likely 1280X960 (or half sizes if it's a portrait orientation);
2) Crop to match a common picture frame size that I feel would be suitable (perhaps useful if sending the photo to the subject);
3) Just crop to what feels right :cool: .

YES! convert to TIFF and work on that.
Phew! I'm glad I decided to leave my master jpeg's alone... boss, I have a couple more questions:

Qa) I thought there was *always* some loss when converting anything to jpeg, so if I convert jpeg1 -> tiff -> jpeg2 will the file jpeg2 have a loss in quality compared to file jpeg1?

Qb) When your shooting RAW what format do you save the master file as (if your using Photoshop do you use psd?) and what format do you use for editing? (My camera can't shoot RAW, I'm just interested).



LayZrHed

[BelyakoV]

why dont you just share some of your work? Dont be afraid to make mistakes.

[Rogue Trooper]

Picture dimensions depend on lots of variables. First, your camera might produce either 2:3 or 3:4 pictures. And most common screen sizes are 4:5.

You crop and resize how it feels best. I crop the picture to get the framing I want, if it isn't right in the original. Then I resize to fit it to screen. All shots doesn't have to be the same size. The more you downsize, the more you can compensate unsharpness in picture. Always quality over size.

You always have loss when you save jpeg. That's why I save my edited psd files too.