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Question on jpeg editing
(I have asked this within another long thread, but this is a slightly different issue...).

People keep saying things to the effect of: if you need to change WB or exposure a lot with a jpeg, you're stuck, so you should have used RAW..

But I change the WB and bring up the exposure on my jpegs all the time... what is this supposed degradation that happens to jpegs that I keep being warned about?.

Seriously, I'm not asking rhetorically... what happens to a jpg if you mess with it too much? Does anyone have an example?.

I keep hearing that RAW will give me the flexibility to pull & tug on the image without worrying about affecting quality... can someone show me a "broken" jpeg so I know what to look out for?.

If I save a new version of the jpeg after I "mess" with it, isn't that "safe" enough, or no?!..

Comments (10)

JChristian wrote:.

(I have asked this within another long thread, but this is a slightlydifferent issue...).

People keep saying things to the effect of: if you need to change WBor exposure a lot with a jpeg, you're stuck, so you should have usedRAW..

But I change the WB and bring up the exposure on my jpegs all thetime... what is this supposed degradation that happens to jpegs thatI keep being warned about?.

Seriously, I'm not asking rhetorically... what happens to a jpg ifyou mess with it too much? Does anyone have an example?.

I keep hearing that RAW will give me the flexibility to pull & tug onthe image without worrying about affecting quality... can someoneshow me a "broken" jpeg so I know what to look out for?.

If I save a new version of the jpeg after I "mess" with it, isn'tthat "safe" enough, or no?!.

You can do wondrous things with your jpegs. yes, you must save it as a new version and you must keep your original just as it came out of the camera. avoid applying jpeg compression over and over on the same file. because each time you save your image, it will apply more jpeg compression..

You keep your original because even tho you can "improve" you original, your original is the best version you have. even tho it might not look it..

Open up an underexposed image and use your levels to improve the contrast and exposure. that is move the white point so it touches the lighter areas and the black point so it touches the darkest areas... look at what happens to your histograms while you make this adjustment. it will start to "comb". that is, your 8 bits starts to get spread out thinly. working on an 8 bit image is like having so much butter for your bread.



The advantage of raw is you have 12 bits to work with. so you have more butter for your bread. you have that extra butter to play with without having to resort to spreading things thinly..

Some things can't be done your raw conversion. you can fix white balance but you can't fix, for example, a mixed colour cast. that is, two colour casts in the one photo caused by,for example, using flash in the foreground and incandescent lighting in the background..

It's certainly worth learning what can be done after your raw conversion. or with your jpeg straight from the camera. a lot of books and on-line resources assume your starting with an 8 bit image whether it's from a raw conversion or from a jpeg..

With jpeg, remember don't save over your original, or resave the same file as jpeg over and over again. some people don't like jpeg because it is compressed. but use your camera's finest quality setting and you shouldn't see any jpeg artefacts at all. part of managing jpeg compression is simple file management and workflow. that is, always keep your original, save a master copy of your edited version in a non-lossy format, don't save the same file as jpeg over and over again...

Comment #1

I touched on the subject in this post:.

Http://forums.dpreview.com/...forums/read.asp?forum=1002&message=24890022..

Comment #2

Saying, correct me if I'm wrong, that the 3rd picture is the best that can be done by editing the 1st picture jpg, because jpg editing means the adjustments you can make are not as extensive since the original file does not have all of the potential data as if it were a RAW file....

I mean, I care about the "look" certainly, and I agree that the RAW edit (2nd pic) looks much better..

If I'm using Lightroom & occasional PSE, is it easier/quicker to achieve the look in that 2nd pic because I'm using RAW vs using jpeg?.

Thanks,jchristian..

Comment #3

That is correct..

If no editing is done, there is no real advantage to raw..

If editing is done, an advantage is there. Whether or not it will be noticeable depends on the edit and the picture. Slight edits with saturation, contrast, and sharpening usually won't show a visible difference..

More extreme edits (perhaps curve adjustments) tend to show the difference more - especially in the highlight areas. The reason the highlight areas are affected more is because of how the data is stored in the RAW file. It holds a lot more information about the highlights than the JPEG..

The other thing besides highlights that the RAW data handles better, is resisting banding or posterization. Depending on your editor, the changes you make while editing will accumulate rounding errors, which can cause posterization. Levels and curves adjustments can cause it too. http://en.wikipedia.org/wiki/Posterization This problem is usually only noticeable in the sky, with it's slight gradients..

I hope that helps...

Comment #4

Clint Sanders wrote:.

That is correct..

If no editing is done, there is no real advantage to raw..

If editing is done, an advantage is there. Whether or not it will benoticeable depends on the edit and the picture. Slight edits withsaturation, contrast, and sharpening usually won't show a visibledifference..

More extreme edits (perhaps curve adjustments) tend to show thedifference more - especially in the highlight areas. The reason thehighlight areas are affected more is because of how the data isstored in the RAW file. It holds a lot more information about thehighlights than the JPEG..

....

I hope that helps..

It does, thanks. My "issue" is that 1. I wouldn't know how to do more advanced editing anyway and 2. I like the way my jpegs look from my K100d (with DA40), so the editing I'm doing is WB, contrast, occasionally bringing up brightness to bring out shadow-detail....

Question: If I'm using Lightroom & occasional PSE, is it easier/quicker to achieve the look in that 2nd pic because I'm using RAW vs using jpeg?..

Comment #5

I can't answer for lightroom. I'm not familiar with editing RAW straight from PSE, but if you exported the raw data as a 16bit TIFF, opened it with PSE, it is easier to get the look of the second pic than if you were just editing the JPG..

The particular changes I made was basically a curve adjustment that made the shadows a bit brighter, and the highlights darker. I believe the following tool can do the same in PSE:.

Http://news.vertustech.com/...by-easy-Filterplugin-for-Adobe-Photoshop.aspx.

I used my own program though. http://www.growlersoftware.com/downloads/VDR.zip..

Comment #6

Much appreciated. I'll have a look at both of those...

Comment #7

You are talking about editing and saving a jpeg. do not do it. use save as and save as a tiff and do not edit or touch the original jpeg in any way..

Bring the jpeg into the pc, put it into say pe5 and make your adjustments, then use save as and save as a tiff..

I have a folder that is labeled jpegs and all my original jpegs go in it. that way if I need the original it is available. any future editing or anything else are done on the tiffs. tiffs cn be resaved forever and there is no degradation to the file..

You mentioned pp the jpegs and how much. the answer of what you can get away with is how far you have to fix/adjust the jpeg. if the exposure or wb is a long way from normal and being right then you should really start with a raw image. raw allow more massive fixes. if you re simply tweaking the image then use the jpeg, but you should have the jpeg fairly close to being right as it comes from the camera. this requires more care and thought when you shoot the jpegs...

Comment #8

GaryDeM wrote:.

You are talking about editing and saving a jpeg. do not do it. usesave as and save as a tiff and do not edit or touch the original jpegin any way.bring the jpeg into the pc, put it into say pe5 and make youradjustments, then use save as and save as a tiff..

I have a folder that is labeled jpegs and all my original jpegs go init. that way if I need the original it is available. any futureediting or anything else are done on the tiffs. tiffs cn be resavedforever and there is no degradation to the file..

You mentioned pp the jpegs and how much. the answer of what you canget away with is how far you have to fix/adjust the jpeg. if theexposure or wb is a long way from normal and being right then youshould really start with a raw image. raw allow more massive fixes.if you re simply tweaking the image then use the jpeg, but you shouldhave the jpeg fairly close to being right as it comes from thecamera. this requires more care and thought when you shoot the jpegs..

OK, so unless I "go RAW", the way to do things is to save any jpegs that I feel needs editing into a Tiff, then edit the Tiff as much as I can (and of course then re-save the Tiff as a new, separate jpg version for easier sharing). Thanks for the info...

Comment #9

The way I do it is to bring the jpeg to pe5 or cs2, make adjustments if any, then save as a tiff. the tiffs I keep into assorted folders on a ext hdr drv with a backup ext hdr drv. any future needs of the image is met from the corrected tiff. I make jpegs from it for the web, send a jpeg to kodakgallery.com and jumbogiant.com for large prints, or anything else comes from the corrected tiff. 8x10 or smaller printing I do myself..

In any event the original jpeg stays in the jpeg folder while the corrected tiff stays in whatever folder it ends up in. I donot delete either one ever. I currently have 97gb of images in my ext hdr drv. this includes some that were scanned in from slides. I have been shooting slr/dslr since 1970...

Comment #10

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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