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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

NEF files (1 Viewer)

Leif

Well-known member
I've noticed that when I edit a NEF file in Nikon Capture by for example changing the white balance, the size of the saved file changes. Does this mean that a) information is being lost by the editing, thus editing in NC is not like using layers in Photoshop or b) that the information is all there, but changes in the file size are due to the compression algorithm being less or more efficient changes are made?

My guess is that NC is making the changes to the underlying data, therefore it makes sense to retain an unedited copy.

Also, is NEF lossless? I heard rumours that it uses a lossy compression algorithm.

Leif
 
Leif said:
Also, is NEF lossless? I heard rumours that it uses a lossy compression algorithm.
Those rumors are more than likely Nikon bashing malarkey put out by people who feel that because they are not Nikon users they should try to make Nikon products look bad. If it has any loss do you think it would be possible for anyone to tell the difference? I can barely tell the difference between a NEF and a JPG large, Fine with my D70 on the computer monitor and absolutely cannot in an 8x10. Which is to say that the JPEG is good, not that the NEF is bad!

As for the file size changes:
I would conclude from my knowledge of how any image file works that changing the white balance or compensation alters the raw data of the image(it has to to change brightness and/or colour), thus changing size. The same way a darker or lighter scene or one that is monotone as opposed to one that is colourful affects image file size.
 
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Tyler Vargo said:
Those rumors are more than likely Nikon bashing malarkey put out by people who feel that because they are not Nikon users they should try to make Nikon products look bad. If it has any loss do you think it would be possible for anyone to tell the difference? I can barely tell the difference between a NEF and a JPG large, Fine with my D70 on the computer monitor and absolutely cannot in an 8x10. Which is to say that the JPEG is good, not that the NEF is bad!

As for the file size changes:
I would conclude from my knowledge of how any image file works that changing the white balance or compensation alters the raw data of the image(it has to to change brightness and/or colour), thus changing size. The same way a darker or lighter scene or one that is monotone as opposed to one that is colourful affects image file size.

Tyler: It isn't Nikon bashing as you put it but merely a desire to understand, and I don't think Nikon are perfect. I'm sure Canon et al also have some 'issues'. I keep reading about Canon cameras such as the 20D 'crashing' and requiring a reset. I guess that Bill Gates is the Canon role model.

I can tell the difference between JPG and NEF if and when I make lots of adjustments. That is when it matters. For example I tend to adjust the highlights using curves, and/or contrast masking. Leif
 
There IS some compression of RAW data - see p.75 of "Nikon D70 - by Simon Stafford" Magic Lantern Guides ISBN - 1 -57990-618-4

Sorry, I have to go off line and work right now ! Will pop back later and type the relevant paragraph, but there is some loss of data according to Mr Stafford.


Later,


Linz
 
Leif said:
Tyler: It isn't Nikon bashing as you put it but merely a desire to understand, and I don't think Nikon are perfect. I'm sure Canon et al also have some 'issues'. I keep reading about Canon cameras such as the 20D 'crashing' and requiring a reset. I guess that Bill Gates is the Canon role model.

I can tell the difference between JPG and NEF if and when I make lots of adjustments. That is when it matters. For example I tend to adjust the highlights using curves, and/or contrast masking. Leif

There's stacks of D70s and 20Ds around so there's always going to be some that fail.

I was checking the file sizes on some very similar RAW files from my 20D and they range from 6.84Mb to 7.5Mb so there's obviously some sort of compression involved there, as well. I would imagine that Canon and Nikon would both use some form of lossless compression.
 
Re: the D70 compressed NEF issue.

It's absolutely the case that there's some "loss" - though whether it's a loss you'll actually miss is another issue (and based on the following quote from this discussion http://groups.google.com/group/rec....854c43e736c0610?sa=X&oi=groupsr&start=2&num=3 I don't think it would worry me...)

The D70's NEF storage does involve some loss compared to the
ultra-raw sensor readings, though according to Nikon, none that you would
see. Roughly (according to Thom Hogan), all 12 bits are saved for shadow
and low mid-tones; high mid-tones and highlight values are split into a
number of different sized groups (i.e. a certain amount of rounding takes
places within a number of intensity bands). This is (supposedly) done in a
non-linear way that mimics the way our eyes work.
 
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