Results 1 to 15 of 15

Thread: D70/s RAW files (NEFs) are not lossless!

  1. #1
    Senior Member
    Join Date
    Dec 2004
    Location
    NTU and Wdls
    Posts
    2,622

    Default D70/s RAW files (NEFs) are not lossless!

    Hmmm I've always been told that RAW files are lossless...
    Seems like I'm wrong. Stumbled across this about compressed NEFs

    http://www.majid.info/mylos/weblog/2004/05/02-1.html
    brief summary - loss of data in the shadow region due to lower resolution in quantizing data. Compresed NEFs are only capturing 9.4 bits of data as opposed to 12 bits of data.
    Means: Loss of shadow detail.
    The maths and the mechanical and technical details all works out, though I've not gotten my hands on any coding to verify, but this guy seems solid enough.

    subsequently did a few searches.. and this:
    http://www.robgalbraith.com/bins/mul...6269-6285-6288
    As with previous Nikon digital SLR models, Nikon describes the compressed RAW setting as numerically lossy but visually lossless. Translated, that means the RAW data after compression is not numerically identical to the RAW data before compression: some picture information has changed. Like a low-compression, high-quality JPEG setting, however, Nikon is promising that it will not be possible to see the data loss.
    OK I know this may not be news to some of you, but hey it's definitely news to me. I've always been brainwashed to accept that RAW files are not lossy. I know most of you will say that you never had problems with compressed NEFs, but I think should stop with the "all RAW files are lossless" thing.

  2. #2

    Default Re: D70/s RAW files (NEFs) are not lossless!

    How about this (about halfway down the page)?

    http://www.kenrockwell.com/nikon/d70lens.htm

  3. #3
    Senior Member
    Join Date
    Dec 2004
    Location
    NTU and Wdls
    Posts
    2,622

    Default Re: D70/s RAW files (NEFs) are not lossless!

    ya. I read that. Apparently he's the only one going around saying that.
    Ken Rockwell has said himself to be non technical, more of a artist than anything else.

    I'm just pointing out something that someone has shown in actual fact rather than stating it based on general knowledge.

    I rem there was one article stating that uncompressed NEFs preserve highlights much better than uncompressed NEFs for a D200, I just gave it a pass. Now I sorta link back to it.. it does makes sense..

    Perhaps one day we find someone with a D200 and we take some photos with extreme dynamic ranges and we can compare.

    but regardless, haha we should just shoot shoot shoot..

  4. #4

    Default Re: D70/s RAW files (NEFs) are not lossless!

    eh shoot in tiff then...

  5. #5
    Senior Member
    Join Date
    Dec 2004
    Location
    NTU and Wdls
    Posts
    2,622

    Default Re: D70/s RAW files (NEFs) are not lossless!

    LOL nothing wrong with shooting in compressed NEFs. For me RAWs are great fun to work with, though not if there's like tons of them..
    I just want to point out that shouldn't say RAWs are lossless..

  6. #6
    Member
    Join Date
    Jul 2005
    Location
    Bt Batok
    Posts
    768

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by unseen
    LOL nothing wrong with shooting in compressed NEFs. For me RAWs are great fun to work with, though not if there's like tons of them..
    I just want to point out that shouldn't say RAWs are lossless..
    did nikon ever claim tt nef is lossless?

  7. #7
    Senior Member
    Join Date
    Feb 2003
    Location
    The heart of the Abyss
    Posts
    2,307

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Thom Hogan had said it all the way back to D100 IIRC. It is "virtually lossless" meaning that there is still some loss...

  8. #8
    Senior Member
    Join Date
    Feb 2003
    Location
    The heart of the Abyss
    Posts
    2,307

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by roti_prata
    did nikon ever claim tt nef is lossless?
    The exact word from the manual, IIRC, is "virtually lossless". Others had already experimented and found that it chops off about 2-3 bits at the highlight ends as the eye is not uniformly sensitive to brightness.

  9. #9
    Senior Member
    Join Date
    Dec 2004
    Location
    NTU and Wdls
    Posts
    2,622

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by roti_prata
    did nikon ever claim tt nef is lossless?
    ???
    Why is Nikon in the picture? I'm clearing up the misconception that RAW files (as in, a generalization) are NOT lossless, and that raw files do NOT automatically provide you with 12 bits of data.

    it's more like MOST RAW files are lossless and provide you with 12 bits of data.

    LOL moral of the story: Get the D200 and shoot uncompressed NEF!

  10. #10
    Member
    Join Date
    Jul 2005
    Location
    Bt Batok
    Posts
    768

    Default Re: D70/s RAW files (NEFs) are not lossless!

    u said:
    Quote Originally Posted by unseen
    Compresed NEFs are only capturing 9.4 bits of data as opposed to 12 bits of data.
    Means: Loss of shadow detail.
    tts y i ask if nikon ever claimed its lossless

  11. #11

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by unseen
    http://www.majid.info/mylos/weblog/2004/05/02-1.html
    brief summary - loss of data in the shadow region due to lower resolution in quantizing data. Compresed NEFs are only capturing 9.4 bits of data as opposed to 12 bits of data.
    Means: Loss of shadow detail.
    The maths and the mechanical and technical details all works out, though I've not gotten my hands on any coding to verify, but this guy seems solid enough.
    What have you been reading?

    The loss is in the highlights, not in the shadows.

  12. #12
    Senior Member
    Join Date
    Nov 2004
    Location
    Northern California
    Posts
    666

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by reflecx
    What have you been reading?

    The loss is in the highlights, not in the shadows.
    just wondering..... is there any details in highlights to begin with?

  13. #13
    Member
    Join Date
    Jul 2005
    Location
    Bt Batok
    Posts
    768

    Default Re: D70/s RAW files (NEFs) are not lossless!

    Quote Originally Posted by idor
    just wondering..... is there any details in highlights to begin with?
    good point

    is it possible to darken highlights the way we brighten shadows?

  14. #14
    Senior Member
    Join Date
    Dec 2004
    Location
    NTU and Wdls
    Posts
    2,622

    Default Re: D70/s RAW files (NEFs) are not lossless!

    oops, heh ya it's the highlights. Sorry, guess I was sleeping..

    Of course there are details in the highlights. Highlights simply refers to the lightest portions of a photograph or halftone, as compared to midtones and shadows. It's a mistake to take it as the absolute region where total loss of details are lost.

    If you care to read more about it:
    http://www.adobe.com/digitalimag/pdf...kflow_sec2.pdf

    This simply shows the amt of data loss from 12 bits to 10 bits in the highlight region.
    http://www.normankoren.com/digital_tonality.html

    From 2048 levels (12 bits) in zone 1 to 512 levels (10 bits).

    You can get more details back from highlights than from shadows. As long as they're not washed-out.

    Well, don't take my word for it. In RAW, go over-expose a photo by 2 stops, and take the same by under exposing by 2 stops.
    Whatever it is, you will get comparatively more details back rather than the under exposed one (across the entire image).
    Last edited by unseen; 18th February 2006 at 01:39 AM.

  15. #15
    Senior Member
    Join Date
    Jul 2003
    Location
    Tampines, Singapore.
    Posts
    1,899

    Default Re: D70/s RAW files (NEFs) are not lossless!

    the main practical difference between lossy JPEG and lossy RAW, is that you operate and save JPEG files, each time incurring more and more quantisation and compression errors, while you never operate on and save your RAW files.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •