Saving RAW as TIF

Discussion in 'Digital Photography' started by mike regish, Mar 31, 2005.

  1. mike regish

    mike regish Guest

    I tried saving a RAW image as a tiff so I could play with it in PS5.5. I was
    surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    the straight data from the ccd and that tif at least wouldn't compress it,
    but why is it so much bigger?

    Also, is there any advantage to working with the raw file as opposed to tif?

    mike regish
     
    mike regish, Mar 31, 2005
    #1
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  2. mike regish

    Jim Townsend Guest

    mike regish wrote:

    > I tried saving a RAW image as a tiff so I could play with it in PS5.5. I was
    > surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    > the straight data from the ccd and that tif at least wouldn't compress it,
    > but why is it so much bigger?
    >
    > Also, is there any advantage to working with the raw file as opposed to tif?


    You don't mention what camera you're using, but most use some
    level of lossless compression when creating RAW files. This
    is to save memory card space.

    It sounds like you might be saving as 16 Bit TIFF.. I think
    PS 5.5 can only handle 8 bit images so you're not gaining anything
    by saving as 16 bit TIFF for editing.

    You'll need Photoshop CS or Photoshop Elements 3.0 to do
    proper 16 bit editing.
     
    Jim Townsend, Mar 31, 2005
    #2
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  3. mike regish

    mike regish Guest

    I'm using the Dimage Viewer software that came with the Minolta 7D. It has 2
    choices for saving as tif-24 and 48 bit. The 48 bit was clicked when I
    opened it. Is this the same thing you're referring to?

    mike

    "Jim Townsend" <> wrote in message
    news:...

    > You don't mention what camera you're using, but most use some
    > level of lossless compression when creating RAW files. This
    > is to save memory card space.
    >
    > It sounds like you might be saving as 16 Bit TIFF.. I think
    > PS 5.5 can only handle 8 bit images so you're not gaining anything
    > by saving as 16 bit TIFF for editing.
    >
    > You'll need Photoshop CS or Photoshop Elements 3.0 to do
    > proper 16 bit editing.
    >
    >
    >
    >
    >
     
    mike regish, Mar 31, 2005
    #3
  4. mike regish

    Ken Weitzel Guest

    mike regish wrote:
    > I'm using the Dimage Viewer software that came with the Minolta 7D. It has 2
    > choices for saving as tif-24 and 48 bit. The 48 bit was clicked when I
    > opened it. Is this the same thing you're referring to?
    >
    > mike


    Hi Mike...

    If it helps any, saying 8 or 24 in this context is the same thing :)

    8 bits times 3 colours = 24 bits total

    and of course 16 bits times 3 colours = 48 bits.

    Ken
     
    Ken Weitzel, Mar 31, 2005
    #4
  5. mike regish

    Jim Townsend Guest

    mike regish wrote:

    > I'm using the Dimage Viewer software that came with the Minolta 7D. It has 2
    > choices for saving as tif-24 and 48 bit. The 48 bit was clicked when I
    > opened it. Is this the same thing you're referring to?


    Yes..

    8 bit refers to how many bits in a single color. There are
    three primary colors so the total is 8 x 3 = 24 bits.

    With 48 bit you have 48 / 3 = 16 bits per color.

    (Just another confusing thing :)
     
    Jim Townsend, Mar 31, 2005
    #5
  6. mike regish

    mike regish Guest

    OK. I was wondering why the big difference.

    Thanks.

    mike

    "Ken Weitzel" <> wrote in message
    news:p2K2e.858732$8l.748846@pd7tw1no...
    >
    > Hi Mike...
    >
    > If it helps any, saying 8 or 24 in this context is the same thing :)
    >
    > 8 bits times 3 colours = 24 bits total
    >
    > and of course 16 bits times 3 colours = 48 bits.
    >
    > Ken
    >
     
    mike regish, Mar 31, 2005
    #6
  7. mike regish

    Scott W Guest

    I did not see this mentioned yet, in raw data there is only one 12 bit
    value for each pixel, when this is converted into color data there now
    needs to be three values for each pixel, even if these values are only
    8 bits you now are storing 24 bits for each pixel where you were
    storing 12 before, now it you are using 16 bits / color, this jumps to
    48 bits per/pixel or 4 time the space for the raw data, add to that
    some losselss compression in the raw file and you have a large increase
    when saving to tiff.

    Scott
     
    Scott W, Mar 31, 2005
    #7
  8. mike regish

    Sheldon Guest

    "Scott W" <> wrote in message
    news:...
    >I did not see this mentioned yet, in raw data there is only one 12 bit
    > value for each pixel, when this is converted into color data there now
    > needs to be three values for each pixel, even if these values are only
    > 8 bits you now are storing 24 bits for each pixel where you were
    > storing 12 before, now it you are using 16 bits / color, this jumps to
    > 48 bits per/pixel or 4 time the space for the raw data, add to that
    > some losselss compression in the raw file and you have a large increase
    > when saving to tiff.
    >
    > Scott


    Okay, now I don't get it. Compression is compression. If you compress a
    file it has to come back to it's original size so you can see it. How does
    a RAW file act as a lossless compression without changing anything when you
    open and close it? I thought a tiff file was "no" compression at all. Does
    RAW have more to do with the file coming straight from the camera with
    little or no changing of the file in the camera, regardless of settings?
     
    Sheldon, Mar 31, 2005
    #8
  9. mike regish

    C Wright Guest

    On 3/30/05 10:31 PM, in article ,
    "Sheldon" <> wrote:

    >
    > "Scott W" <> wrote in message
    > news:...
    >> I did not see this mentioned yet, in raw data there is only one 12 bit
    >> value for each pixel, when this is converted into color data there now
    >> needs to be three values for each pixel, even if these values are only
    >> 8 bits you now are storing 24 bits for each pixel where you were
    >> storing 12 before, now it you are using 16 bits / color, this jumps to
    >> 48 bits per/pixel or 4 time the space for the raw data, add to that
    >> some losselss compression in the raw file and you have a large increase
    >> when saving to tiff.
    >>
    >> Scott

    >
    > Okay, now I don't get it. Compression is compression. If you compress a
    > file it has to come back to it's original size so you can see it. How does
    > a RAW file act as a lossless compression without changing anything when you
    > open and close it? I thought a tiff file was "no" compression at all. Does
    > RAW have more to do with the file coming straight from the camera with
    > little or no changing of the file in the camera, regardless of settings?
    >
    >

    It is possible to compress a file on a lossless (no-loss) basis. An example
    of this is in Photoshop when you save as a Tiff you are presented with a
    second dialog box that lets you select, among others, LZW compression. If
    you choose LZW the file compresses without loss. A similar thing happens
    with raw files. When these files are opened they open back to their true
    size.
     
    C Wright, Mar 31, 2005
    #9
  10. mike regish

    Ron Hunter Guest

    mike regish wrote:
    > I tried saving a RAW image as a tiff so I could play with it in PS5.5. I was
    > surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    > the straight data from the ccd and that tif at least wouldn't compress it,
    > but why is it so much bigger?
    >
    > Also, is there any advantage to working with the raw file as opposed to tif?
    >
    > mike regish
    >
    >

    In spite of its name, a RAW file has been processed to some degree. A
    TIFF file just stores 24 bits of information for each pixel, making very
    large files.


    --
    Ron Hunter
     
    Ron Hunter, Mar 31, 2005
    #10
  11. mike regish <> wrote:
    > I tried saving a RAW image as a tiff so I could play with it in PS5.5. I was
    > surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    > the straight data from the ccd and that tif at least wouldn't compress it,
    > but why is it so much bigger?
    >
    > Also, is there any advantage to working with the raw file as opposed to tif?
    >
    > mike regish
    >


    You should be able to save the TIFF file with LZW or ZIP (the latter is
    not supported in all software) compression. Doing so will greatly
    reduce the file size. If you save as a PSD file, you will see the same
    expansion in file size. Do your work in a format that doesn't suffer
    data loss with each save [i.e. .psd or .tiff] and then when you are
    done, export the JPEG at quality level 10 and 300 dpi cropped to your
    print size (i.e. 8x10"). If you don't perform the cropping yourself,
    the printers software [or the human operator] will crop it for you and
    you may not get what you actually wanted. Also, if you print to mass
    printers like Walmart, Target, Walgreen's and Shutterfly or Ofoto, then
    it would be wise to save the JPEG in their colorspace of sRGB as well.
    If you use the better retailers like MPIX.com, you can leave the JPEG in
    Adobe RGB (1998).


    --
    Thomas T. Veldhouse
    Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1
    Spammers please contact me at .
     
    Thomas T. Veldhouse, Mar 31, 2005
    #11
  12. mike regish

    Eric Gill Guest

    "Sheldon" <> wrote in
    news::

    > Okay, now I don't get it. Compression is compression. If you
    > compress a file it has to come back to it's original size so you can
    > see it.


    Good so far.

    > How does a RAW file act as a lossless compression without
    > changing anything when you open and close it?


    You don't "open and close" a RAW file. The act of "opening" a RAW file
    creates a copy in an intermediate format which must be saved in something
    besides RAW. Think of it as "reading" and not "opening."

    > I thought a tiff file
    > was "no" compression at all.


    No, there are a number of compressions available for Tiff, some lossless,
    some not. Generally, though, the idea is to use something that is
    lossless for a working file.

    > Does RAW have more to do with the file
    > coming straight from the camera with little or no changing of the file
    > in the camera, regardless of settings?


    NOTHING changes in the camera in a RAW file. It is the RAW data right off
    the sensor, no post processing. RAW processor software such as C1 or ACR
    does the job.

    There are, unfortunately, some RAW formats (i.e., particular camera
    bodies) that actually use lossy compression, which are the sole exception
    to the above statement. I believe either the marketing department or R &
    D for those companies are smoking crack.
     
    Eric Gill, Mar 31, 2005
    #12
  13. mike regish

    paul Guest

    mike regish wrote:

    > I tried saving a RAW image as a tiff so I could play with it in PS5.5. I was
    > surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    > the straight data from the ccd and that tif at least wouldn't compress it,
    > but why is it so much bigger?
    >
    > Also, is there any advantage to working with the raw file as opposed to tif?



    There is an advantage to working with the raw file with the newer raw
    converter plugin for PS CS and other raw converters like Nikon Capture
    that allow adjusting curves in the raw image before it's converted. See
    what your raw converter can do & use that as the first step. I find I
    don't use photoshop for much using the tools in the raw converter to
    adjust brightness and contrast most of the time. Once it's adjusted,
    it's OK to save in 8-bit (jpeg even) but if you are going to do curves &
    levels, it's best to start with 16 bit, then crunch it down to 8 before
    saving. Another alternative is to do a linear conversion with DCRAW
    command line freeware converter. You'll need to use the correct wide
    gamut color profile but I think this comes close to preserving the most
    information if you plan to make adjustments.
     
    paul, Mar 31, 2005
    #13
  14. mike regish

    Ron Krebs Guest

    "Jim Townsend" <> wrote in message
    news:...
    > mike regish wrote:
    >
    > > I'm using the Dimage Viewer software that came with the Minolta 7D. It

    has 2
    > > choices for saving as tif-24 and 48 bit. The 48 bit was clicked when I
    > > opened it. Is this the same thing you're referring to?

    >
    > Yes..
    >
    > 8 bit refers to how many bits in a single color. There are
    > three primary colors so the total is 8 x 3 = 24 bits.
    >
    > With 48 bit you have 48 / 3 = 16 bits per color.
    >
    > (Just another confusing thing :)
    >
    >


    Let's go the extra mile here and mention that 24-bit then equates to 2^24
    power or 16,777,216 color combinations whereas the 48-bit gives you a
    whopping 281,474,976,710,656 shades of color!!! Nearly 300 trillion colors.
    Hmmm, I wonder what kind of monitor I should get for that? : )

    Ron
     
    Ron Krebs, Mar 31, 2005
    #14
  15. mike regish

    Guest

    An 8 MegaPixel camera with a 12-bit A/D creates 12 MBytes of data.
    This gets losslessly compressed to 8 MBytes (huffman coding) as RAW

    The RAW file contains only one color pixel for each sensor location. A
    process known as demosaicing (or deBayering) creates RGB from the
    singel location by interpolating surrounding pixels. There are about 22
    different algorithms, each with advantages and disadvantages.

    When you convert a RAW to 16-bit TIFF, the 8 MByte file expands to
    12MBytes, is demosaiced into 36 MBytes and then each 12-bit pixel
    is stored in a 16-bit container for a total of 48MBytes of size.

    Mitch
     
    , Mar 31, 2005
    #15
  16. mike regish

    Paul Revere Guest

    On Thu, 31 Mar 2005 06:13:32 -0800, Thomas T. Veldhouse wrote
    (in article <424c058c$0$193$>):

    > mike regish <> wrote:
    >> I tried saving a RAW image as a tiff so I could play with it in PS5.5. I
    >> was
    >> surprised to see the file size jump from 8 meg to 35 meg. I figured raw was
    >> the straight data from the ccd and that tif at least wouldn't compress it,
    >> but why is it so much bigger?
    >>
    >> Also, is there any advantage to working with the raw file as opposed to tif?
    >>
    >> mike regish
    >>

    >
    > You should be able to save the TIFF file with LZW or ZIP (the latter is
    > not supported in all software) compression. Doing so will greatly
    > reduce the file size. If you save as a PSD file, you will see the same
    > expansion in file size. Do your work in a format that doesn't suffer
    > data loss with each save [i.e. .psd or .tiff] and then when you are
    > done, export the JPEG at quality level 10 and 300 dpi cropped to your
    > print size (i.e. 8x10"). If you don't perform the cropping yourself,
    > the printers software [or the human operator] will crop it for you and
    > you may not get what you actually wanted. Also, if you print to mass
    > printers like Walmart, Target, Walgreen's and Shutterfly or Ofoto, then
    > it would be wise to save the JPEG in their colorspace of sRGB as well.
    > If you use the better retailers like MPIX.com, you can leave the JPEG in
    > Adobe RGB (1998).
    >
    >
    >


    According to Mpix website: "Mpix printers output in sRGB color space"

    http://www.mpix.com/help.aspx?

    Click FAQs

    Click What Color Space Does Mpix Accept
     
    Paul Revere, Apr 1, 2005
    #16
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