Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

If this is repetitious my apologies.

Jpegs are an output format. They are limited to 8 bit depth - or 24 bit color - each of the 3 channels have only 256 tonal steps. Due to this limitation, a jpeg can only support the smallest color space - sRGB.

Compression on save is the least of the issues, and unless you heavily compress an image and try to make a billboard from it, you won't see any issues.

A jpeg image, either out of camera or the final output from a raw workflow, represents only the data that is needed to show the image, and discards all the rest (8 bit vs 14 or 16 bit), and shows only the colors that it can show that were present in the original scene. Most of the time this works fine.

There are times when it doesn't. Particularly when you have colors that are beyond the tiny gamut of sRGB - flowers, birds and insects (iridescence), and scenes with wide contrast ranges - that are breathtaking to see, but are beyond the capabilities of 8 bit sRGB.

Luckily, most DSLRs and other cameras can record 12 bit color, pro cameras can record 14 bit, and a few, like Leica, Hasselblad and PhaseOne can record 16 color files. The difference is color accuracy and editing headroom in shadow and highlight areas. There is more, cleaner image information in shadows, and greater information in the brightest areas that can contribute to a more dynamic and dramatic image. Not to mention that you have much more control over things like sharpening, color and tonal shifts, etc that would make a jpg look like crap if you do too much of it, even if you follow a non-destructive workflow and do all of your editing in one save.

This is all possible because a 12 bit raw file can capture 4,096 tonal steps per color, and a 14 bit raw file can do 16,384 steps.

Given the higher bit depth and the potentially better quality possible with a raw workflow that is both nondestructive and faster/more flexible - there is no reasonable rationale to defend anyone owning a camera with raw capability and not utilizing it. This is aside from a few narrowly defined specialties like reportage - where it is verboten to alter an image in any way beyond cropping, forensics, and portraiture where you have total control over the lighting and the subjects typically have color gamut that can easily be covered by sRGB.

This may help:

http://laurashoe.com/2011/08/09/8-versus-16-bit-what-does-it-really-mean/

blackest Loc: Ireland

It's worth considering that there are raw presets (for many camera's) that will process a RAW file to the same visual state as the out of camera jpeg.
However they stop just before converting to a jpeg leaving all that RAW data available to let you customize your image or just save as is. You don't have to spend a lot of time to get back to where the camera would have taken you anyway.

mostly we just want small adjustments from the standard jpeg and that is achieved very easily using a camera preset as a starting point.

DirtFarmer Loc: Escaped from the NYC area, back to MA

I understand that due to time constraints, jpg can be the way to go, but I've never really understood why it would be necessary to shoot jpg instead of RAW just because "modification" of the image is prohibited.

After all, you can change the camera settings to produce fairly "wild" results in the SOOC jpg.

bull drink water Loc: pontiac mi.

lets say for a moment that you limit opening and editing to 5 times per file. will deterioration be noticeable???? how many people open and edit the same file over 5 times????????????

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

True - time constraints in reportage along with the rule of no alterations means that the photographer must "nail" the exposure, since the best images are often passing glimpses of the world around them. Another setting is when you are doing a commercial shoot, and you have the creative director breathing down your neck - these are often done tethered, and once they approve the shot it is committed - no need or reason to do anything else to the image other than a little "sprucing up" But white and color balance, tonal balance, hue saturation and luminance, contrast etc are all either on the money or very close.

DirtFarmer Loc: Escaped from the NYC area, back to MA

I'm happy to say I've never been in that position.

oldtigger Loc: Roanoke Virginia-USA

creative directors are just like new mothers in law, just more polite.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Those of us who are OCD. :)

Seriously - I have been going through files that I initially edited in 2006 - and found some very nice surprises - reinterpreting them with newer better software. I am so happy I had the original raw files.

Kuzano

Not quite sure what you are saying. But this about JPEG compression.

EVERY TIME you do a file-save or file-save as command, the compression algorythm kicks in (at the level or percentage of the quality slider) whether you make edit changes or not.

Therefore, when you make the copy of the original, if you save it (rename to new file for edit purposes) you kick in a compression.

You should only create the copy after you do the rename AND the edits, because each and every save runs the compression algorythm.

If your procedure is to:

Do a file save as, and rename to create a copy and YOU SAVE IT.

And then you do your edits, and SAVE the Edits.

You just made two compression runs at the percentage of the quality slider.

Minimal compression would be to pull up an original, DO YOUR EDITS, then file save as, then rename it. Then when you activate the Save As with a new name, you are not affecting the original, but editing and creating the new-name file, with only one compression.

I think that what I heard you say was rename and save the copy, then edit and save again..... Nope... two compressions.

Just be careful not to save your edits back to the original... make the copy as you save the edits with the new name.

bigwolf40 Loc: Effort, Pa.

Minimal compression would be to pull up an original, DO YOUR EDITS, then file save as, then rename it. Then when you activate the Save As with a new name, you are not affecting the original, but editing and creating the new-name file, with only one Just be careful not to save your edits back to the original... make the copy as you save the edits with the new name..... Kuzano> Finely I have someone that what I was saying understands exactly what I was trying to explain and this is the way I do my PP. And you can do this over without effecting the original.....Rich

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

That is not completely correct. Opening a compressed file and saving it, even as a new file, still recompresses the image data, causing degradation.

The only way you can circumvent generational loss of data and quality is to save it to an UNCOMPRESSED format, like psd or uncompressed tiff. Saving it to jpeg will just recompress and cause data loss.

Apaflo Loc: Anchorage, Alaska

It can be saved in any lossless compressed format and need not be uncompressed. TIFF using either Adobe Deflate or LZW compression is very portable. PSD or whatever the proprietary format your editor uses is better in the sense that it can no doubt save more information, and not as good in being less portable to other programs.

DirtFarmer Loc: Escaped from the NYC area, back to MA

That's true if you overwrite the original file. I think the poster was saying that opening the file, editing it, and writing it to a new file with a different name would preserve the original file. True, the new file with a different name is slightly degraded by the write operation, but the original file has not been rewritten.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Correct!