Post-Processing RAW vs Post-Processing TIFF

Discussion in 'Digital Photography' started by Mike Henley, Nov 22, 2004.

  1. Mike Henley

    JPS Guest

    In message <BAPId.1169$>,
    Oh, great; that all we need - outr cards being filled in the background.

    8-bit TIFFs lose lots of highlight precision, and usually clip some of
    the top of the dynamic range if they are made to be immediately
    viewable. They are about 50% bigger than RAW, even if they use the LZW
    compression (and have less and less-precise information).

    For Bayer-sensor cameras, RAW is it; really. If they find better ways
    of losslessly compressing RAW, great, but keep your TIFFs.
    --
     
    JPS, Jan 23, 2005
    #21
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  2. Mike Henley

    rafe bustin Guest

    No.

    The truth is that a so-called "six megapixel"
    digicam has 1.5 million red sensors, 1.5 million
    blue sensors, and 3 million green sensors.

    It's not really "six megapixels" at all, but
    it's now become standard practice to rate
    and specify digicams this way.

    [Foveon sensors are another story...]

    The RAW file needs only to encode six million
    digital values -- ie., the readings from these
    six million sensors. Reconstruction into
    RGB "pixels" is done within the RAW converter.

    If the file were in TIF format, you'd need
    18 million encoded values -- assuming you're
    calling this a "six megapixel" image.

    JPG is actually somewhat appropriate for
    encoding digicam images, but is not nearly
    as flexible as RAW. That is, with RAW,
    you can reinterpret the six million sensor
    readings at will. With JPG you must live
    with the effects of the original interpretation.


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Jan 23, 2005
    #22
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  3. Mike Henley

    Bill Hilton Guest

    Speaking of TIFF, why don't more cameras offer a TIFF option for
    Tiff is about 300% larger than low ISO RAW for 8 bit files with my Canon dSLR
    cameras. 16 bit tiffs would be about 600% larger.
     
    Bill Hilton, Jan 23, 2005
    #23
  4. Mike Henley

    rafe bustin Guest


    No. Lossless compression just doesn't work
    that well for most photographic images.

    To the extent that there's a lot of sharp
    detail in the image, the compression gets
    worse (ie., less effective.)

    Try it for yourself with WinZip. The
    compression will vary quite a bit depending
    on the nature of the image -- but typically
    isn't much more than 15-20%.

    JPG, on the other hand, is specifically
    optimized for images and to take advantage
    of the nature of human vision. So while it
    is regarded as "lossy" (and it is) the
    compression is terrific, and the actual
    losses (in practice) can be made almost
    negligible.


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Jan 23, 2005
    #24
  5. Mike Henley

    JPS Guest

    In message <>,
    It *is* six megapixels, because light levels are recorded at six million
    different 2D locations in the focal plane. A pixel does not equal R + G
    + B.
    --
     
    JPS, Jan 23, 2005
    #25
  6. Mike Henley

    Larry Guest

    You will NEVER convince him, EVER!

    You and I will sit here KNOWING that the Bayer system works really well
    (better than anything else tried for digital, so far) and that it aproximates
    the way the human eye works, but pixel peepers around wont be satisfied, EVER

    If you gave them a million dollars, they would complain that it is GREEN &
    WRINKLED.
     
    Larry, Jan 23, 2005
    #26
  7. Mike Henley

    JPS Guest

    In message <>,
    You mean 300% larger or 300% as large? The former means 4x.
    --
     
    JPS, Jan 23, 2005
    #27
  8. Mike Henley

    JPS Guest

    In message <>,
    Gather them together, and we'll see if any of them can tell the
    difference between two foveon images in Lab mode with the 'a' and 'b'
    channels pixelized to two pixels, at normal viewing magnifications.
    --
     
    JPS, Jan 23, 2005
    #28
  9. Actually on my camera (Olympus E-1), TIFF takes more space than RAW, and there
    are other cameras where RAW saves even more due to being compressed (it isn't
    compressed on the E1). However, TIFF is still subject to a lot of problems
    that JPG has (in camera processing possibly losing details, clipping of dynamic
    range from 12-ish bits to 8). All that is avoided by using TIFF instead of
    JPG, is any artifacts caused by the JPG lossy compression.
     
    Michael Meissner, Jan 23, 2005
    #29
  10. Mike Henley

    rafe bustin Guest


    Not at all, I've made the same arguments
    myself several times, right down to the
    explanation of the a and b channels in
    Lab space. I fully appreciate the cleverness
    of the Bayer sensor.

    Even so, by the time I'm screwing with
    the image in Photoshop, every pixel has
    to have a Red, Green and Blue coordinate
    (or some set of coordinates in whatever
    type of color space I'm using at the time.)

    A "pixel" in terms of my 10D's Bayer sensor
    isn't the same thing as a "pixel" in
    Photoshop. The point of my explanation
    was to explain the relative sizes of TIFF
    vs. JPG vs RAW files.

    So save your uppercase shouting for
    someone else, OK?


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Jan 23, 2005
    #30
  11. Mike Henley

    Bill Hilton Guest

    Perhaps the firmware for COMPRESSED tif files is prohibitive.

    Compressed 8 bit-channel tiff's using LZW or ZIP are generally still larger
    than RAW files. Plus you have the problem of opening them, many (maybe most)
    software apps won't open LZW compressed tiff files.

    I once tried compressing 16 bit-channel tiffs and they just don't compress well
    with LZW or ZIP, some of the "compressed" files were actually larger than the
    uncompressed ones and none had savings of even 10%. So for 16 bit files you're
    still looking at about 6x the memory space compared to RAW.

    RAW is the way to go, you can generate your tiff later, several different ways
    if need be, and it's much smaller on the cameras I've used.
     
    Bill Hilton, Jan 23, 2005
    #31
  12. Mike Henley

    Bill Hilton Guest

    Tiff is about 300% larger than low ISO RAW for 8 bit files with my
    Canon dSLR
    MB per 8 bit/channel tiff (for those easily confused by %'s).
     
    Bill Hilton, Jan 23, 2005
    #32
  13. Mike Henley

    Larry Guest

    I am chagrined, however, the common claim of 6, or 8 megapixels for a Bayer
    camera is generally accepted to mean 6 or 8 megapixels of luminance
    information, nowhere on any of the packaging, manuals, or advertising do any
    of the (Bayer) manufacurers claim that these cameras give 6 (or 8) million
    RGB pixels..Except for Fuji, where the picture size and pixel count is
    accomplished by magic dwarves living inside the camera. (but they still dont
    claim anything about RGB pixels.

    People who spend the bucks to buy a digital camera should have done enough
    research to understand this BEFORE buying the camera, not after.
     
    Larry, Jan 23, 2005
    #33
  14. Mike Henley

    rafe bustin Guest


    The "vast majority" of digicam users don't
    know or care about such subtleties, just as
    the vast majority of film camera users
    don't know or care about how film or
    cameras work.

    Of much greater concern is that many
    digicam users don't know anything at
    all about the need to archive their
    images, and will be in for a rude
    surprise somewhere down the road.

    Those who know the difference between
    RAW, TIF and JPG are already ahead of
    the game, at least they're asking the
    right questions and know what a file is.


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Jan 23, 2005
    #34
  15. Mike Henley

    Larry Guest

    Had a look at your website.. nice stuff.

    bably agree as to vast majority.. though my feelings on the subject are
    probably less helpfull than yours. I tend to feel if they dont investigate
    before spending money, then they dont qualify for free help.

    I guess Im just a grumpy old curmedgeon.
     
    Larry, Jan 23, 2005
    #35
  16. Mike Henley

    Matt Ion Guest

    Another problem is that there are so many variations on TIFF - even a
    simply freeware app like IrfanView gives you the option of saving with
    no compression, or using LZW, Packbits, JPEG, or ZIP compression...
    PMView Pro also offers the option to apply horizontal differencing for
    LZW compression, the choice of "White is zero" or "Black is zero"
    photometrics, selectable encoding strip sizes (4k, 8k, 16, 32k and
    single-strip), and the use of either Intel (LSB-first, PC-standard) or
    Motorola (MSB-first, Mac-standard) byte ordering...

    All of these have different uses and different benefits and drawbacks
    depending on specifics of the image. You can'e expect the camera to
    always choose the right one. And some software doesn't support some
    forms of compression (I tried loading a TIFF into my Avery label
    software and it complained that it didn't support LZW compression -
    resaving the file without compression allowed it to load).
     
    Matt Ion, Jan 24, 2005
    #36
  17. Mike Henley

    Ray Fischer Guest

    As long as we're wishing for features...

    What I'd really like to see is a camera that can talk to a USB storage
    device. The cameras already do FAT file systems and already do USB.
    If you could have the camera transfer pictures from the flash card to
    a USB hard disk then people wouldn't have to spend hundreds of dollars
    on devices that do the same.
     
    Ray Fischer, Jan 29, 2005
    #37
  18. Mike Henley

    rafe bustin Guest


    There's not much difference... there are portable
    devices for well under $200, including 20G or 40G
    hard drive, which will read a CF card and copy
    it to the hard drive. Several examples here:

    <http://www.mydigitaldiscount.com/>


    rafe b.
    http://www.terrapinphoto.com
     
    rafe bustin, Jan 29, 2005
    #38
  19. Mike Henley

    Lionel Guest

    Kibo informs me that (Dr. Joel M. Hoffman) stated that:
    No. TIFF is far less space efficient than RAW. Try converting a RAW file
    to 16 bit TIFF yourself, & you'll find that the TIFF file is much,
    *much* larger than the original RAW file.
     
    Lionel, Jan 29, 2005
    #39
  20. Mike Henley

    Ron Hunter Guest

    Don't understand marketing, do you? Grin.
    They have to make PROFIT, you know.
     
    Ron Hunter, Jan 29, 2005
    #40
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