Topic: RAW photo file....

[johnw]

I have experienced degradation of jpeg images over time. I have also read that this can happen. My impression was that it is similar to opening a cd in windows explorer and copying the wav file using the copy/paste command. A copy of the data is made, but it is not an accurate copy. Do this many times and eventually the wav files become noticeably different, and that is why people should use Exact Audio Copy. Same thing with an mp3, make copies of copies of copies and the final file is different than the original.

Here's a link that came up when I googled "jpeg degradation". The 2 images shown are similar to what I have seen with my own images. Unfortunately, I don't think I have a non-degraded jpeg or I'd provide an example also.

http://www.patricktaylor.com/1940

At this point, I archive everything as raw and occasionally tiff in addition to jpeg.

EDIT: After further reading, there appears to be lots of conflicting information about this. I am definitely not an expert on this, but feel I have experienced what I would call jpeg degradation. With data storage and memory so cheap, it makes sense to me to just shoot raw+jpeg or at least in raw. If I'm wrong and jpeg degradation doesn't really exist, then I've wasted only a small amount of money/time on paranoia/bad information.

[johnw]

That said, a shot that is at the wrong ISO, shutter speed or aperature setting can't be saved even if taken in raw.

I don't find that to be true at all, with the possible exception case of the wrong setting dropping the shutter speed so it's too slow to freeze action -- though I suppose it depends on how one defines "wrong".

While having an aperture, shutter speed, or ISO setting different than one intends -- not "wrong", necessarily, because there are a variety of configurations and exposures one might use to achieve a desired artistic effect -- may result in results different that one expected, I've found shooting RAW provides substantial opportunity for post-processing -- both "corrective" and editorial.  With unintended settings, can one produce precisely the image one intended in the first place?  Maybe, maybe not.  But can one salvage a quality image close to what one intends?  Absolutely.

For example, one might underexpose by 1 stop (or 2 stops, or some other reasonable value, etc.) due to a narrower aperture than one intended, on a shot in which a specifically shallow depth of field isn't critical and one maintains a sufficiently fast shutter speed to stop the action as desired.  The exposure in this instance might be "wrong", i.e. different than one intended, but I've found RAW provides sufficient opportunity to correct the exposure and still yield excellent results.  Just as RAW provides opportunity to correct "wrong" exposures (under easier than over), it also enables better white balancing, noise reduction, etc., all of which may contribute to high quality final images, even if one doesn't nail the exposure configurations as desired.

Of course, there's a point beyond which one can't recover even a RAW file, but RAW provides far more latitude for editing, and recovery, editing than JPG.

Perhaps "wrong" was a poor word choice. A real life example would be setting the ISO at 1600 for shooting a concert, waking up the next morning and forgetting to drop the ISO back to 100 for shooting in bright sunlight. You can work on the noise with some software after the fact, but if you open the raw image, you can't change the ISO to 100 after the fact. Another example is grabbing your camera to shoot something quickly and just plain blanking on looking at the settings. If its night time and your settings were ISO 100, speed 1000, aperature 8, that image is going to be straight black on black even if shot in raw.
Edit: Also shooting in raw can not salvage a shot that is out of focus

[Brian Skalinder]

Points on "wrong" settings, johnw.  Regarding JPG copying and the link...

http://www.patricktaylor.com/1940

...here's the key:

The second is the same image after it was saved and closed, then opened again, 50 times.

The changes seen aren't due to simple digital copying of a digital file, e.g. from one HDD location to another.  They're due to the opening and re-saving of the JPG multiple times.  As someone else noted, opening and saving a JPG isn't the same as a digital copy.  With a digital copy, the 0s and 1s that make up the JPG are simply duplicated elsewhere.  With an open/save, the 0s and 1s are fundamentally changed by the application of the compression algorithm during every save.

[dmonkey]

I think it's not uncommon to get about 2 stops of exposure latitude from a RAW file, whereas JPG pretty much locks you in. Maybe that's a poor way to say it, but I've been able to pull detail out of shadows and bring highlights down in RAW that I wouldn't have had much luck on with JPG images. I really like the flexibility of RAW. Sure, you still need to get the exposure right for best results, but RAW gives quite a bit of exposure latitude after-the-fact if you were only "close" and not "perfect" with exposure.

I print by developing my RAW files into TIFF.

[sabre]

I have experienced degradation of jpeg images over time. I have also read that this can happen. My impression was that it is similar to opening a cd in windows explorer and copying the wav file using the copy/paste command. A copy of the data is made, but it is not an accurate copy. Do this many times and eventually the wav files become noticeably different, and that is why people should use Exact Audio Copy. Same thing with an mp3, make copies of copies of copies and the final file is different than the original.

Here's a link that came up when I googled "jpeg degradation". The 2 images shown are similar to what I have seen with my own images. Unfortunately, I don't think I have a non-degraded jpeg or I'd provide an example also.

http://www.patricktaylor.com/1940

At this point, I archive everything as raw and occasionally tiff in addition to jpeg.

EDIT: After further reading, there appears to be lots of conflicting information about this. I am definitely not an expert on this, but feel I have experienced what I would call jpeg degradation. With data storage and memory so cheap, it makes sense to me to just shoot raw+jpeg or at least in raw. If I'm wrong and jpeg degradation doesn't really exist, then I've wasted only a small amount of money/time on paranoia/bad information.

To be frank, you're just perpetuating misinformation. JPG degradation only occurs when you save a JPG.
If you simply copy the file (using Window Explorer) from one location to another there is no loss involved. This is a fact.

[gearscout]

OK, it's true -- jpeg only degrades when it's saved.  Copy it first, then edit that one.  (Because you NEVER forget, do you?)

But RAW (NEF in Nikon) is much more than that.  Why do you think there are 20MB in a full frame file instead of 5?

Using a non-destructive editor/manager like Lightroom, you have unlimited possibilities with RAW/NEF.  Edit the B&W version, the color version, the infrared version, no problem.

You can't white balance a jpeg.  You CAN White balance a RAW file.

The full dynamic range of your camera, the possibilities of the lighting, all captured in a single file called RAW.

vs.

The rendering of aforementioned data by your in-camera processor adding varying degrees of sharpening, vivacity and color balance.

It's simple.

Just take your pick!

;-)