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#31
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raw files are HUGE
On Wed, 11 Apr 2007 23:14:45 +0100, John Bean wrote:
You may be right, but couldn't thumbnails be available in uncompressed form even though the main image has been compressed? The thumnail (and bigger preview) in most raw files is a JPEG anyhow, so it's even more compressed than the raw data ;-) Note that I'm didn't state how thumbnails are or aren't stored. I just suggested that there shouldn't be a good reason why thumbnails *must* be compressed. I'd think that the cameras that store a normal jpeg image along with the raw files (some cameras using a single file to store both, others saving two separate files) might well want to compress the jpegs, but there wouldn't be as good a reason to force the compression of the much smaller thumbnails. Many raw files are a variant of TIFF, so the compression of the image data is independent of the thumbnail(s) stored elsewhere in the file. That's why a simple registry patch for Windows to tell it that a NEF or a DNG is just a TIFF in disguise results in Explorer showing thumbs for those files despite having no idea what the raw data inside the file actually represents, compressed or not. Correct, Explorer doesn't have a "preview" option for NEF files, but does when they're renamed to .TIFF, and then it shows a very small thumbnail. That doesn't necessarily indicate that TIFF is in any way similar to NEF, ORF or other raw files, just that other non-raw components may be stored similarly in TIFF and raw files. Don't some cameras create much larger TIFF files than raw files? That would indicate that one isn't quite the other in disguise. |
#32
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raw files are HUGE
In article , John Bean
wrote: On Wed, 11 Apr 2007 17:38:08 -0400, ASAAR wrote: On Wed, 11 Apr 2007 13:55:34 -0700, Ken Lucke wrote: It's just not worth it - IMO, if you're going to be shooting (AND keeping, including /keeping/ /track/ /of/) that many files, the slight savings in disk space is not really *even* going to be a factor. Besides, if they're compressed, you're not going to have a thumbnail preview available to quickly look at them in the Finder or the Windows browser (all you're going to have is the icon for whatever file type they are), so you're going to have to decommpress them /just/ to see what they are when trying to find one, if you don't use management tools like Aperture or Lightroom - and you /can't/ use them if you are using compressed files. You may be right, but couldn't thumbnails be available in uncompressed form even though the main image has been compressed? The thumnail (and bigger preview) in most raw files is a JPEG anyhow, so it's even more compressed than the raw data ;-) Many raw files are a variant of TIFF, so the compression of the image data is independent of the thumbnail(s) stored elsewhere in the file. That's why a simple registry patch for Windows to tell it that a NEF or a DNG is just a TIFF in disguise results in Explorer showing thumbs for those files despite having no idea what the raw data inside the file actually represents, compressed or not. I don't think you understand. If you compress ANY file into a .zip, ..sit, .rar, .sitx, or whatever, the file then becomes that file type, until uncompressed again. Any emmbedded preview, thumbail, or other data is all compressed right along with the rest of the data, and thus is not accessible to the OS to display. Unless you specifically generate (taking the extra time, CPU cycles, and knowledge to do so) a custom icon/thumbnail for each and every file, it shows up in the operating system as the generic icon for that type of compressed file. -- You need only reflect that one of the best ways to get yourself a reputation as a dangerous citizen these days is to go about repeating the very phrases which our founding fathers used in the struggle for independence. -- Charles A. Beard |
#33
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raw files are HUGE
On 2007-04-11, ASAAR wrote:
Correct, Explorer doesn't have a "preview" option for NEF files, but does when they're renamed to .TIFF, and then it shows a very small thumbnail. That doesn't necessarily indicate that TIFF is in any way similar to NEF, ORF or other raw files, just that other non-raw components may be stored similarly in TIFF and raw files. DNG files use the TIFF structure to encode the information. If NEF files can be seen as previews when renamed to .TIFF, then they likely follow the same kind of structure. When converting MRW files to DNG files, the Adobe DNG converter (with the default settings) produces TIFF files containing a uncompressed thumbnail image, a small JPEG sub-file, along with the actual RAW data as another sub-file. A program that knows how to handle JPEG-in-TIFF files may even be able to view the embeded picture in addition to the thumbnail, but a raw converter would be needed to access the full data. Don't some cameras create much larger TIFF files than raw files? That would indicate that one isn't quite the other in disguise. A TIFF image file contains red+green+blue components for each pixel, totalling 3 or 6 bytes per pixel (depending on if the data is stored as 8 or 16 bit data). This data may be compressed with LZW, but that wouldn't likely produce more than a 25% reduction in size. On the other hand, raw files contain only one of the red, green, or blue components per pixel, and is usually packed as 2 values in 3 bytes for 12-bit sensor data. Adobe DNG files may be further compressed losslessly internally with JPEG-LS, which achieves about a further 40% size reduction compared to the packed data size. FWIW, the compression used internally in DNG files is significnatly more effective than any other external compressor I've tried on either my original MRW files or uncompressed DNG files, and I've tried a quite few (zip, 7zip, rar, rzip, and bzip2). -- Bruce Guenter http://untroubled.org/ |
#34
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raw files are HUGE
On Wed, 11 Apr 2007 16:01:06 -0700, Ken Lucke
wrote: I don't think you understand. If you compress ANY file into a .zip, .sit, .rar, .sitx, or whatever, [snip] Sorry, cross purposes. I thought you were referring to compression of the raw image in the file rather than external compression of the file itself. I agree with your point. -- John Bean |
#35
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raw files are HUGE
On Apr 12, 1:08 am, Bruce Guenter wrote:
[snip] DNG files use the TIFF structure to encode the information. If NEF files can be seen as previews when renamed to .TIFF, then they likely follow the same kind of structure. [snip] Correct. In fact, NEFs and DNGs are so similar that you can do a lot of examination of NEFs using the dng_validate.exe tool from the DNG SDK. -- Barry Pearson http://www.barrypearson.co.uk/photography/ |
#36
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raw files are HUGE
On Wed, 11 Apr 2007 14:06:31 -0700, Ken Lucke
wrote: In article , Ken Lucke wrote: within minutes of walking in the door, thus giving me the ability to store 300,000 MORE raw files than I was capable of doing a few minutes Oops, sorry, I think I slipped a couple of decimal points there. Try 30,000,000 more. You slipped again, and in the wrong direction. 322,122,547,200 bytes storage (300 GB - [yes I know there's some slight overhead lost]) / 10240 byte files (average) == 31,457,280 files 1024 bytes is 1 KB (Kilobyte) so that calculation is for 10 KB files, not 10 MB files. A 300 GB disk holds approximately (allowing for overhead etc.): 300 1 GB files (duh? :-) 3,000 100 MB files 30,000 10 MB files jc -- "The nice thing about a mare is you get to ride a lot of different horses without having to own that many." ~ Eileen Morgan of The Mare's Nest, PA |
#37
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raw files are HUGE
In article , JC Dill
wrote: On Wed, 11 Apr 2007 14:06:31 -0700, Ken Lucke wrote: In article , Ken Lucke wrote: within minutes of walking in the door, thus giving me the ability to store 300,000 MORE raw files than I was capable of doing a few minutes Oops, sorry, I think I slipped a couple of decimal points there. Try 30,000,000 more. You slipped again, and in the wrong direction. 322,122,547,200 bytes storage (300 GB - [yes I know there's some slight overhead lost]) / 10240 byte files (average) == 31,457,280 files 1024 bytes is 1 KB (Kilobyte) so that calculation is for 10 KB files, not 10 MB files. A 300 GB disk holds approximately (allowing for overhead etc.): 300 1 GB files (duh? :-) 3,000 100 MB files 30,000 10 MB files Yeah, you're right. I've been having a bad week, my brain is not functioning properly (that's what happens when virtually your entire life gets wiped out by identity theft). -- You need only reflect that one of the best ways to get yourself a reputation as a dangerous citizen these days is to go about repeating the very phrases which our founding fathers used in the struggle for independence. -- Charles A. Beard |
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