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Author Topic: Uncompressed NEF or Compressed or Lossless Comp?  (Read 9471 times)
Anthony Mann
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« on: January 30, 2009, 04:58:35 PM »
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I have been using uncompressed NEF with a D300 for all of my shots, however was curious if anyone has found a difference in terms of image quality and the workable range of exposure in uncompressed, compressed and lossless compressed NEF modes.  I shoot pics that I don't crop much, and my maximum print size is no more than 13" wide and up to 44" long (stitched panoramics), however I do take photos of outdoor scenes that often have exposure extremes...  Thanks for your input!  -AM
« Last Edit: January 30, 2009, 05:23:07 PM by Anthony Mann » Logged
Philip Weber
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« Reply #1 on: January 30, 2009, 06:27:57 PM »
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Quote from: Anthony Mann
I have been using uncompressed NEF with a D300 for all of my shots, however was curious if anyone has found a difference in terms of image quality and the workable range of exposure in uncompressed, compressed and lossless compressed NEF modes.  I shoot pics that I don't crop much, and my maximum print size is no more than 13" wide and up to 44" long (stitched panoramics), however I do take photos of outdoor scenes that often have exposure extremes...  Thanks for your input!  -AM


I use lossless compression NEF on my D700 & D300 and have found no IQ issues vs. uncompressed NEF, nor have I read of any. You might want to do a query in the Nikonians.org forum, which I've found to be an excellent Nikon specific resource, along with LL of course. Additionally, your manual might have some info on it (don't know where mine is to check) but in my D300 & D700 manuals by Thom Hogan, I don't see anything one way or the other on it. I only print up to 13 x 19, so I do not have any personal experience beyond that.  

All the best,
Phil
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Panopeeper
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« Reply #2 on: January 30, 2009, 06:46:52 PM »
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Quote from: Anthony Mann
if anyone has found a difference in terms of image quality and the workable range of exposure in uncompressed, compressed and lossless compressed NEF modes

1. The difference between uncompressed and losslessly compressed is exactly what it says. After decompression of the raw data there is no difference whatsoever. It affects the file size and the processing time: uncompressed files are processed faster.

2. The lossy compression is designed as a Darwinian selection: go that way and you get what you deserve.
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Gabor
Tony Beach
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« Reply #3 on: January 31, 2009, 12:55:58 AM »
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Practically everybody I'm aware of uses Lossless Compressed.; 12 bit versus 14 bits, now that starts a debate.
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Slough
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« Reply #4 on: January 31, 2009, 04:17:54 AM »
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Quote from: Panopeeper
1. The difference between uncompressed and losslessly compressed is exactly what it says. After decompression of the raw data there is no difference whatsoever. It affects the file size and the processing time: uncompressed files are processed faster.

Are you sure? A compressed file will require more time to process i.e. compress, but it will write more quickly to the flash card, as the file size will be smaller. I do not know the answer to this question as I have not performed tests.
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Anthony Mann
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« Reply #5 on: January 31, 2009, 07:53:28 AM »
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Ok, I'd like to add two additional  questions - How much, in terms of % of space savings, have you received by using lossless compressed over standard compresed, and has the time lag writing to cards been an issue for anyone shooting slower than 8fps mode?

I'll have to run some tests on some color gradients (e.g., the sunset) this weekend to see if there is a big enough difference between these modes!


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Panopeeper
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« Reply #6 on: January 31, 2009, 10:36:01 AM »
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Quote from: Slough
Are you sure? A compressed file will require more time to process i.e. compress, but it will write more quickly to the flash card, as the file size will be smaller
1. The specialized processor of the camera can compress many times faster than a PC; this should not be an issue.

2. Whether writing on the card lags behind the shooting depends on many factors. A camera with 7fps, 20Mpix will run sooner in buffer shortage than one with 3fps, 12Mpix. Of course the card's speed is a big factor as well.

3. Reading and decompressing of compressed images on a PC is usually much slower than reading the larger, uncompressed file.

Quote from: Anthony Mann
Ok, I'd like to add two additional  questions - How much, in terms of % of space savings, have you received by using lossless compressed over standard compresed
See the link below; what you don't find there: the 14bit lossless is 16-20MB, the 14bit lossy is 12-14 MB.

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has the time lag writing to cards been an issue for anyone shooting slower than 8fps mode?
http://www.dpreview.com/reviews/nikond300/page13.asp

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I'll have to run some tests on some color gradients (e.g., the sunset) this weekend to see if there is a big enough difference between these modes!
This is a bit naive; it is not under your control. Banding may occur is particular situations. You may have luck and experience banding with your trials, but you may not see any problem, decide for the lossy compression, shoot months long and suddenly realize, that a few images are ruined.

Btw, "standard compression" is a misnomer. It was a mistake by Nikon (in fact, they are misleading the customers) to name them "compression and lossless compression". Nikon had difficulty with this issue for years; their description of the lossiness changed with each model. The proper terminology would be "lossless compression vs. lossy compression", or even better "compressed vs. garbled".
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Gabor
ejmartin
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« Reply #7 on: January 31, 2009, 09:46:42 PM »
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There is indeed zero difference in the data between uncompressed and losslessly compressed NEFs.  Gabor has an agenda wrt lossy compression however.  If you are interested in an unbiased investigation of lossy compression, a good starting point is Jeffrey Friedl's blog post

http://regex.info/blog/photo-tech/nef-compression

and a possible reasoning behind the Nikon's compression algorithm is put forth at

http://theory.uchicago.edu/~ejm/pix/20d/te...#NEFcompression
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emil
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« Reply #8 on: February 01, 2009, 03:16:59 AM »
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Quote from: Panopeeper
1. The specialized processor of the camera can compress many times faster than a PC; this should not be an issue.

2. Whether writing on the card lags behind the shooting depends on many factors. A camera with 7fps, 20Mpix will run sooner in buffer shortage than one with 3fps, 12Mpix. Of course the card's speed is a big factor as well.

3. Reading and decompressing of compressed images on a PC is usually much slower than reading the larger, uncompressed file.

Without meaning to be rude, the above is rather obvious. I was wondering about real data, and whether or not in practice compression time is significant, and if so, when.
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Panopeeper
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« Reply #9 on: February 01, 2009, 10:51:01 AM »
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Quote from: Slough
I was wondering about real data, and whether or not in practice compression time is significant, and if so, when.
I am wondering, what real data means for you. I was writing about the raw file, which mainly consist of the raw image data; that is, which may be compressed (losslessly or lossily), or uncompressed. There are other images in the file as well, but they are always compressed lossily (JPEG thumbnail and preview).
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Gabor
NikosR
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« Reply #10 on: February 03, 2009, 03:07:53 AM »
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Lossless compressed is what the word says: Lossless. If lossless compression were loosing data you wouldn't be able to be using much of the Internet not much of many computer applications around. Trivial example of lossless compression: aaaabbbcddddd can be encoded as 4a3bc5d saving 6 characters in the process while retaining all data since the original string can be accurately decoded from the encoded one given the encoding algorithm.

In the case of higher end Nikon cameras there's always an advantage (in terms of performance and card storage capacity) in shooting lossless compressed vs uncompressed. That means that the penalty you are paying in terms of CPU cycles in compressing the data in camera is offset by increased buffer performance, camera to card write performance and card storage capacity savings.

However, Panokeeper has a point that in post-processing opening compressed files is somewhat slower than opening uncompressed files, an issue only if you are processing large batches of images with inefficient apps on underpowered hardware. This is the only reason why one might want to choose uncompressed vs. losslessly compressed on a Nikon camera.
« Last Edit: February 03, 2009, 03:13:54 AM by NikosR » Logged

Nikos
madmanchan
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« Reply #11 on: February 03, 2009, 09:26:13 PM »
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You are unlikely to see visual differences, due to the encoding scheme of the lossy NEF compression which is based on a roughly perceptually-linear curve. You are technically losing the most data in the highlights, but that is precisely the area that we are least sensitive to.

(For a similar reason, we tend to observe shadow noise even though in reality the most noise exists in the highlights. In other words, the absolute noise levels are highest in the highlights, but the visual noise levels are greatest in the shadows.)
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Panopeeper
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« Reply #12 on: February 03, 2009, 10:27:38 PM »
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Quote from: madmanchan
You are unlikely to see visual differences, due to the encoding scheme of the lossy NEF compression which is based on a roughly perceptually-linear curve. You are technically losing the most data in the highlights, but that is precisely the area that we are least sensitive to

http://www.adobeforums.com/webx?14@862.PbTtixVT48L@.59b77d0e
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Gabor
madmanchan
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« Reply #13 on: February 04, 2009, 08:04:57 AM »
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I do not see anything in that thread that suggests the artifacts are due to the lossy NEF compression scheme.
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inissila
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« Reply #14 on: February 04, 2009, 09:19:25 AM »
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Quote from: Anthony Mann
I have been using uncompressed NEF with a D300 for all of my shots, however was curious if anyone has found a difference in terms of image quality and the workable range of exposure in uncompressed, compressed and lossless compressed NEF modes.  I shoot pics that I don't crop much, and my maximum print size is no more than 13" wide and up to 44" long (stitched panoramics), however I do take photos of outdoor scenes that often have exposure extremes...  Thanks for your input!  -AM

It's almost impossible to see any difference in image quality between compressed, lossless compressed, and uncompressed NEF in my experience. The compression seems to be visually lossless in practice.

However, whenever space permits I use uncompressed NEF as it allows faster processing of NEF files, and the difference on my current and previous computers has been quite significant. Batch conversion of D3 NEFs to TIFF might take 4.5 or 7 seconds per file, depending on whether the files are uncompressed or compressed. My time is far more valuable to me than storage space, so I select uncompressed unless I am totally running out of card space, which happens about twice per year.
« Last Edit: February 04, 2009, 09:25:22 AM by inissila » Logged
Panopeeper
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« Reply #15 on: February 04, 2009, 10:28:53 AM »
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Quote from: madmanchan
I do not see anything in that thread that suggests the artifacts are due to the lossy NEF compression scheme.
Well, I do. In fact I was pretty sure of that immediately, for I have analyzed such cases already, like this; the first one is lossy, the second is lossless, by a Nikon D300:



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Gabor
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