RAW->JPEG, why do my jpeg's seem grainy?

Shima · August 9, 2007

I've been noticing a lot lately, I only started working with RAW this past week, that when I export my photos into JPEG when I'm all done, it seems that they've gotten grainier. Is this just a side effect of having to lighten / up the exposure on darker photos? Or am I saving them wrong? I export 100% jpeg, sRGB so I can upload properly... 300 dpi...

thoughts?

claudermilk · August 9, 2007

Shima wrote:

Is this just a side effect of having to lighten / up the exposure on darker photos?

As Adam from Mythbusters would say: "now there's your problem."

Yes, this is why you are seeing "grain" or rather digital noise. Exposure in digital is critical--even moreso than the famously picky slide film. This is where the whole "expose to the right" theory comes from.

You are much better off getting the exposre nailed in-camera and get your highlights right up against the right side of the histogram. Read here for a very good start in understanding why.

Shima · August 10, 2007

Isn't the point of shooting in RAW though to be able to fix your exposure with less quality loss then in JPEG though? Because I've never had issues like this when I shot in JPEG.

claudermilk wrote:

As Adam from Mythbusters would say: "now there's your problem." Yes, this is why you are seeing "grain" or rather digital noise. Exposure in digital is critical--even moreso than the famously picky slide film. This is where the whole "expose to the right" theory comes from.

You are much better off getting the exposre nailed in-camera and get your highlights right up against the right side of the histogram. Read here for a very good start in understanding why.

Richard · August 10, 2007

Shima wrote:

Isn't the point of shooting in RAW though to be able to fix your exposure with less quality loss then in JPEG though? Because I've never had issues like this when I shot in JPEG.

Yes, that's correct. Generally speaking, you can tweak exposure up to two full stops with decent results. I haven't seen noise problems except when there was a lot of noise in the RAW file. While Chris is certainly correct about getting the exposure right in the first place, I'm guessing that your shooting technique hasn't changed now that you are using RAW. If you are having noise problems that you never saw before, there may be a flaw in your work flow somewhere. It would be helpful if you posted a sample or two (100% crop would be best) with EXIF data and a step by step description of your processing.

Cheers,

arodney · August 10, 2007

Exposure is just as critical with Raw as JPEG but you're feedback to correct exposure is way off thanks to how the manufacturers treat their LCD/Exposure systems (based on film, not Raw). If you truly underexpose the image, you get more noise. Raw is linearly encoded data (JPEG isn't). If you have a 12 bit image with 6 stops of range from shadow to highlight, the first stop of highlight data contains HALF of all the levels (2048 out of 4096). Then next stop half that remaning levels and so on. That's how linear encoded data behaves. Not film or our visual system. Net result is, the LAST stop of shadows in best exposure situations only have 128 levels. Under expose, less than 129 and more noise. And best exposure means placing the data such that you put as much levels as possible in the shadows which means exposing for the Raw highlights so that everything is shifted to the right (also known as Expose to the Right):

http://www.luminous-landscape.com/tutorials/expose-right.shtml

The two stops of exposure 'compensation' is really going to show up when you expose for the highlights, move the exposure slider of CR or LR down 1 or 2 stops (for my 5D, it's 1 ½ stops) to neutralize the rendering for expose to the right. Results, less noise in shadows.

Art Scott · August 10, 2007

Do you "Save as" or "Save for the web" ...this also makes a big difference....do yoiu save as a # 12 jpeg(jpg) in photoshop.

It should be "Save As" and from my printers suggestion a #12 jpg.....also do your sharpening very last.....this was simply a suggestion from my printer and it has helpped me a lot...............

claudermilk · August 10, 2007

Shima wrote:

Isn't the point of shooting in RAW though to be able to fix your exposure with less quality loss then in JPEG though? Because I've never had issues like this when I shot in JPEG.

Yep, and in reality it does. But, to steal another cliche: there's no such thing as a free lunch.

Andrew outlines why you're still seeing noise when bringing exposure up--and gave the exact same link.

The benefit is you have a wider range of adjustment available, the downside is most ofhte time you don't wnat to make use of it unless there is no other choice.

ChrisJ · August 10, 2007

Hi Shima, I had a similar problem and the fix for me was to turn down the default Sharpness in the RAW converter (for me, Photoshop CS2). Just another possibility....

pathfinder · August 10, 2007

Shima wrote:

I've been noticing a lot lately, I only started working with RAW this past week, that when I export my photos into JPEG when I'm all done, it seems that they've gotten grainier. Is this just a side effect of having to lighten / up the exposure on darker photos? Or am I saving them wrong? I export 100% jpeg, sRGB so I can upload properly... 300 dpi...

thoughts?

What ISO are your images shot at?

Are you, or the camera, choosing the ISO?

Sharpening settings in ARC, vs in camera?

Ann McRae · August 10, 2007

ChrisJ wrote:

Hi Shima, I had a similar problem and the fix for me was to turn down the default Sharpness in the RAW converter (for me, Photoshop CS2). Just another possibility....

Yep - that is a good suggestion. I leave sharpening completely out of the RAW conversion process. I am using RSE, and noise reduction isn't available.

I get lots of grain introduced only when developing a very severely underexposed photo.

ann

RAW->JPEG, why do my jpeg's seem grainy?

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