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11/24/2010 08:14:28 AM · #1 |
the .CR2 raw files captured by Rebel XS are about ~9mb. If i export that to a tif its jumps to about 44mb.
were is all that extra information coming from? |
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11/24/2010 08:17:51 AM · #2 |
The file is uncompressed in TIF form.
All the other formats are compressed or filtered down. |
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11/24/2010 08:19:05 AM · #3 |
Originally posted by amsterdamman: The file is uncompressed in TIF form.
All the other formats are compressed or filtered down. |
so my camera compresses the info into a raw file? or further compresses it to a jpg? |
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11/24/2010 08:25:44 AM · #4 |
If you zip the TIF, does the size drop to ~9mb? |
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11/24/2010 08:30:18 AM · #5 |
'tiff' has 4 letters and 'raw' only 3 |
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11/24/2010 08:35:49 AM · #6 |
Originally posted by tholmir: If you zip the TIF, does the size drop to ~9mb? |
never tried.
It seems odd to me that raw would be a compressed format. granted i can see the reason, but wouldn't one expect the option to store an uncompressed file? |
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11/24/2010 08:37:11 AM · #7 |
RAW typically uses lossless compression, whereas JPG is lossy.
TIFF is typically uncompressed, although it supports both lossless (LZW) and lossy (JPG) compression.
Lossless compression is the kind used in Zip, Rar etc, where one needs to be able to extract exactly the same contents that were compressed. Lossy compression removes what is not necessary for the final output, and is typically used in pictures (gif, jpg), audio (mp3, wma) and video (mpg, avc). |
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11/24/2010 09:20:39 AM · #8 |
I've always wondered the same thing...but with the original poster....where does the extra 30+ mbs come from? |
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11/24/2010 09:25:23 AM · #9 |
Originally posted by NathanWert: I've always wondered the same thing...but with the original poster....where does the extra 30+ mbs come from? |
I guess you can say they come from "unpacking" the (lossless-)compressed data from the RAW file. Just like you can unzip a zip file and have the contents take up 4 times as much space as the compressed file did. |
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11/24/2010 09:52:27 AM · #10 |
By the way, for more information about the Nikon DEF format than you ever wanted, this blog entry is very interesting. |
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11/24/2010 10:21:45 AM · #11 |
Yes, compression is involved, but it's not the only thing.
Current Canon CR2 files are 14-bit. TIFF files are 16-bit files.
Unprocessed RAW files have no sharpening. Sharpening does increase file size. To add to that unsharpened images compress more compactly than sharpened files.
But, it's all additive causes. At the end of the day, it boils down to a simple fact - they are different file structures and TIFF wasn't designed to be space considerate.
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11/24/2010 10:28:35 AM · #12 |
9MB sounds about right for the RAW file size. Canon does use lossless compression on their RAW format, resulting in a size that's usually around 1 byte (8 bits) per pixel, a little more for high-detail images. That's a fair amount of compression, when you realize that uncompressed RAW data is 14 bits per pixel location (remember that only one color is recorded at each location).
Now, when you process the RAW data, you wind up with *three* color channels at each pixel location. So, if you export your 10 Mpx file to uncompressed 8-bit-per-channel TIFF, you get 10Mpx * 3 channels * 1 byte/channel = 30 MB. For 16-bit-per-channel TIFF,double that (use 2 bytes per channel). Now TIFF comes in three common flavors... uncompressed, LZW compression, and ZIP compression. Both of the compressed formats are lossless. FWIW, it's also possible to write a TIFF file with (lossy) JPEG compression, though why someone would want to do so is beyond me.
So down to your 44MB TIFF file. I suspect that it is a lossless-compressed 16-bit-per-channel file that would otherwise be 60MB in size. |
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11/24/2010 11:09:47 AM · #13 |
Originally posted by fotomann_forever: TIFF files are 16-bit files. |
Actually, TIFF supports a variety of formats. 16 bit per channel RGB is one of them.
I agree that sharpening could add to the filesize, although I don't recall the OP mentioning any sharpening done on his picture.
As kirbic mentions, a lossless, 16-bit representation of the 10 Megapixels that the 1000D captures would take up 60MB, a 14-bit encoding of the same data would take up around 52 MB. So the question really isn't where the "extra" 35 MB comes from but rather where the 43 MB disappeared when compressing this in the raw file :)
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11/24/2010 02:44:14 PM · #14 |
Try saving the TIF file using the LZW compression option -- the size (on disk) should drop down to around the same size as the RAW file. LZW is lossless compression (essentially the same as ZIP) which can be incorporated right into the TIF file, but not all other programs (e.g. page-layout programs) are/have been able to read it, and you may also lose the thumbnail/preview version. |
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11/24/2010 03:33:31 PM · #15 |
I think you've just answered my unasked question, General.
Conversion from RAW to TIFF used to take a minute or two. Now it can take up to 10 minutes. The difference was switching from TransferNX to TranserNX2. The default settings must be uncompressed now. |
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11/24/2010 04:40:29 PM · #16 |
Doesnt TIF also have an alpha channel associated with it? I think that might add to it as well. |
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11/24/2010 05:31:21 PM · #17 |
Thanks everyone...that finally answered the questions I had. |
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11/24/2010 05:33:56 PM · #18 |
Originally posted by Simms: Doesnt TIF also have an alpha channel associated with it? I think that might add to it as well. |
You can save alpha channels (selections) with TIFF files, but they are not there to start with. In Photoshop, when you save a PSD file as a TIFF you should have the option to retain or discard the alpha channels. |
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11/24/2010 06:57:07 PM · #19 |
Originally posted by GeneralE: Originally posted by Simms: Doesnt TIF also have an alpha channel associated with it? I think that might add to it as well. |
You can save alpha channels (selections) with TIFF files, but they are not there to start with. In Photoshop, when you save a PSD file as a TIFF you should have the option to retain or discard the alpha channels. |
To add, TIFF files even support multiple image data layers. TIFF files also support multiple pages, making them useful for things such as engineering drawings.
Message edited by author 2010-11-24 18:58:10. |
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11/24/2010 07:13:17 PM · #20 |
Originally posted by kirbic:
To add, TIFF files even support multiple image data layers. TIFF files also support multiple pages, making them useful for things such as engineering drawings. |
The only time i have ever seen tiff as engineering drawing is when they are scanned from hardcopies and rarely are they multipage. Most engineering software today will print directly to pdf, and from my experience is the deliverable of choice.
Message edited by author 2010-11-24 19:13:31. |
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11/24/2010 07:52:58 PM · #21 |
Originally posted by mike_311: The only time i have ever seen tiff as engineering drawing is when they are scanned from hardcopies and rarely are they multipage. Most engineering software today will print directly to pdf, and from my experience is the deliverable of choice. |
Someone forgot to tell my Design Engineering Dept... they have thousands of 'em. And yes it is a less efficient way to store them. You are correct that the most common reason is the scan-from-hard-copy scenario, and where an actual signature is required, that still happens. Why we require actual (unreadable, mostly) signatures is beyond me. |
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11/24/2010 08:04:45 PM · #22 |
Originally posted by kirbic: Originally posted by GeneralE: Originally posted by Simms: Doesnt TIF also have an alpha channel associated with it? I think that might add to it as well. |
You can save alpha channels (selections) with TIFF files, but they are not there to start with. In Photoshop, when you save a PSD file as a TIFF you should have the option to retain or discard the alpha channels. |
To add, TIFF files even support multiple image data layers. TIFF files also support multiple pages, making them useful for things such as engineering drawings. |
I've never figured out who to create additional pages -- how does that happen? |
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03/14/2014 12:17:33 AM · #23 |
thread old, but I\'ve met the similar issue to compress image. And now solved. When it comes to TIFF, two main image compression options are available–they’re known as LZW or ZIP. Both ZIP and LZW are lossless compression methods. |
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