Raw noise reduction

Southdowns

Southdowns

Messages
2,820
Name
Mark
Edit My Images
Yes
I know many of my camera settings (eg white balance), make no difference when shooting in raw, but there are two I'm not sure about; high ISO noise reduction, and long exposure noise reduction.

Both appear to operate if I turn them on (eg if I expose for 10 seconds, there's 10 seconds of NR applied), but do these only actually have an effect if I'm shooting jpegs? Logic says yes, but I'm not sure.

Thanks,

Mark
 
long exposure takes another picture with shutter closed and then uses it to remove noise in the original, then the result is processed to jpeg. The warmer the day the more pixel noise you will get ( and the longer the camera has been switched on ), so for very long exposures it can make some difference if you enlarge the picture or print cropped portions.
High ISO NR removes noise generated by the sensor itself when the gain is turned up, I think it does a noise reduction by resampling the original image.

The best way to test this is shoot a fairly even coloured shot, say a close up of a green plant, and try your highest ISO with and without the NR.

In my experience if I go over 1600 ( Nikon D5000) I always start to see speckling with or without NR applied, but then again I always shoot raw so I don't know what the jpeg conversion will do )
 
Thanks John. I get what they do (though I didn't know some of the detail you gave), but the question really is; is there any point in having NR turned on when shooting in raw? After all, raw is raw isn't it; i.e. exactly what the sensor saw?

I'd say I've answered my own question, except that the camera goes through the process if I turn NR on, even though I've set it to shoot in raw only, so I'm wondering if it is in fact doing something to the raw file?
 
I was about to post exactly the same question.

With my EOS, does the high ISO and long exposure NR only do it on the processed jpg OR does it actually resample and alter a RAW image. (i shoot RAW only). Again logic would dictate it only affects a generated JPG but i havent seen that written conclusively anywhere.
 
Last edited:
Southdowns said:
I know many of my camera settings (eg white balance), make no difference when shooting in raw, but there are two I'm not sure about; high ISO noise reduction, and long exposure noise reduction.

Both appear to operate if I turn them on (eg if I expose for 10 seconds, there's 10 seconds of NR applied), but do these only actually have an effect if I'm shooting jpegs? Logic says yes, but I'm not sure.

Thanks,

Mark
Click to expand...

It's a good question and I don't know the answer :) But if you wanted to use noise reduction wiith a raw file you could always take the raw and then take your own dark image and process it in photoshop :thinking:

Edit to add..... I reckon the NR works okay with raw files for one simple reason.... It would be just as easy to subtract a dark frame from a raw file as it would be from a jpeg.
 
Last edited:
Perfect, that answers it, thanks. Shame I now have to go back to waiting for the long exposure NR to be applied (I thought I'd got away with that!), but at least now I know.
 
You must log in or register to reply here.
Back
Top