10-27-2010, 06:46 PM
[quote name='PuxaVida' timestamp='1288169519' post='3811']
Do the raw converter programms (like ACR) uncompress the "lossless compressed" image data or use the produced NEF file as it is recorded by Nikon's compression algorithm? I ask this because first of all I don't know the answer; and second of all, zipping & unzipping is done by the same application, but here in NEF case the applications on the compression and uncompression side are different.
[/quote]
Of course, any software cannot use the compressed data without uncompressing it (ever tried to read a zipped text file?).
And of course, the raw converter has to know the algorithm that was used to compress. I don't know how this is managed. A NEF is essentially a TIF, so it may be that the standard TIF compression algorithm (LZW) is used, which is known by most applications. Or Nikon releases some information if they use a proprietary algorithm.
To summarize, when using lossless compression, there is no possibility that image quality is lost by using a non-optimal decompression algorithm, because there is nothing like a non-optimal algorithm.
Do the raw converter programms (like ACR) uncompress the "lossless compressed" image data or use the produced NEF file as it is recorded by Nikon's compression algorithm? I ask this because first of all I don't know the answer; and second of all, zipping & unzipping is done by the same application, but here in NEF case the applications on the compression and uncompression side are different.
[/quote]
Of course, any software cannot use the compressed data without uncompressing it (ever tried to read a zipped text file?).
And of course, the raw converter has to know the algorithm that was used to compress. I don't know how this is managed. A NEF is essentially a TIF, so it may be that the standard TIF compression algorithm (LZW) is used, which is known by most applications. Or Nikon releases some information if they use a proprietary algorithm.
To summarize, when using lossless compression, there is no possibility that image quality is lost by using a non-optimal decompression algorithm, because there is nothing like a non-optimal algorithm.