RAW (NEF) to JPeg and keep quality

[Steve657]

Hi folks,

So I'm wondering if there's any real loss of quality saving a RAW file to a JPEG.

Synopsis is import a RAW (NEF) file to work on in photoshop and then I wish to share that image with someone that will want the image in JPeg format. Using 'Save As' save the orginal RAW file as a JPEG.

Thanks,

Steve

[Test Screen Name]

There's some loss of quality, but of course a RAW file is useless until it is developed, according to your choices. It isn't even in colour... A PNG or TIFF would preserve your choices exactly, after developing, but a high quality JPEG (CHOOSE the quality) should be fine for every real-world purpose for anything starting in a camera.

[Steve657]

Thank you that confirms what I thought. I was ensuroing I wasn't missing anything.

[D Fosse · Accepted solution]

There is massive loss, and there's no way you can avoid it.

First of all, processing a raw file into an RGB file will in itself throw away lots of data. You're encoding 14 stops of dynamic range into 8 or so, and part of the raw processing is deciding what data to keep and what to throw out.

Second, jpeg is the worst possible format if you want to keep high quality. Jpeg compression is always destructive, non-reversible and cumulative. Not only is it discarding original data, but it's also introducing compression artifacts. Don't be fooled by the setting sometimes called "maximum quality" jpeg, meaning least compressed - there is no such thing as maximum quality when it comes to jpeg. It will degrade the image at any setting.

The only purpose of jpeg is to reduce file size for final delivery, with the implication that the immediately visible quality loss is acceptable. The reason jpeg still survives is because that size reduction is incredibly effective, it can shrink a file down to 2-5% of native size.

Never work on a jpeg, never resave a jpeg if you can avoid it. It will degrade further with every new save.

EDIT cross post. I'm apparently more of a purist than Test Screen Name. But I stand by what I said.

[Steve657]

Brilliant reply thank you. I didn't realsise the damage is accumulative. I was wondering why things were not looking as sharp once I had worked on an image a few times.

It is a useful 'sharing' for internet file but I suppose most professional printing is done in TIFF or PNG?

[D Fosse]

Yes. Printing is usually done from TIFF. PNG is a web format, not intended for print-related work.

Jpeg is usually fine provided you only save out once, at the very end, for final delivery. Save out a jpeg copy from the original master, which should be PSD or TIFF.

While the jpeg damage is normally not immediately apparent (which is why it's still widely used) - it will soon hit you if you do further work on it. Then a jpeg rapidly falls apart.

[NB, colourmanagement net]

@Steve657 "So I'm wondering if there's any real loss of quality saving a RAW file to a JPEG."

There's a massive loss of data, my friend, Photoshop expert Martin Evening wrote that up to 83% or data is lost between RAWand JPEG

Archive a tiff or PSD, make a copy, resize, convert to JPEG. Be SURE of the size needed, JPEG is very damaging if cropped or resized and saved again.

I hope this helps
neil barstow, colourmanagement net - adobe forum volunteer - co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

[TheDigitalDog]

Ideally you want to stick with the raw data. The JPEG engine that processes the raw massively clips and compresses highlights. We often don't when editing the raw. This compression can clump midtones as much as 1 stop while compressing shadow details! People incorrectly state that raw has more highlight data but the fact is, the DR captured is an attribute of the capture system; it's all there in the raw but maybe not in a camera proceed JPEG.

A raw capture that's 10 or 11 stops of dynamic range can be compressed to 7 stops from this JPEG processing which is a significant amount of data and tonal loss! So when we hear people state that a raw has more DR than a JPEG, it's due to the poor rendering or handling of the data to create that JPEG. The rendering of this data and the reduction of dynamic range is from the JPEG engine that isn't handling the DR data that does exists as well as we can from the raw! Another reason to capture and render the raw data, assuming you care about how the image is rendered!

[D Fosse]

A raw capture that's 10 or 11 stops of dynamic range

By @TheDigitalDog

Today that's about 14 stops for the better cameras. It improves all the time. I even notice that I can squeeze a bit more out of the newer sensor in the Sony a7r mark V than I can with the mark III that I still have. It seems there is still more to go on.

That's what you get with linear data vs gamma encoded. It's like a film negative - for those old enough to remember 🙂 - very tonally compressed and not a useful image in itself, but all the information is there for retrieval.