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Thread: What is a Tiff file?

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    arith's Avatar
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    What is a Tiff file?

    I thought Tiff was 16 bit; but after HDR processing both Raw and Tiff of the same image I got true ev span from Raw of 9.6 and only 8.6 from Tiff.

    What is Tiff LZW? In fact what is Tiff since it is an extraordinarily big file compared to Raw?

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    Re: What is Tiff

    TIFF stands for Tagged Image File Format, and uses 2 bytes (ie 16 bits) to describe each red, green, or blue element (ie 6 bytes per colour). LZW is a compression algorithm to held reduce the size of the file (losslessly).

    A RAW file isn't demosaiced, and is compressed - the RAW converter looks at adjacent pixels to determine correct colour information - in other words an 8MP sensor has 2 Million Red, 2 Million Blue and 4 Million Green photo receptors - additional colour info is added during demosaicing to turn that lot into 8 million RGB pixels (ie they extrapolate twice as much data as is actually captured).

    A RAW file will probably be processed into an HDR in a linear gamut space whereas if you work from a TIFF file then the gamut will already have been converted, and some DR lost.

    Does this help?

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    arith's Avatar
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    Re: What is Tiff

    Well it probably will when I look up a few things you said. Cheers Colin :0

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    Re: What is Tiff

    Quote Originally Posted by arith View Post
    Well it probably will when I look up a few things you said. Cheers Colin :0
    Oops - sorry Unfortunately it's a bit of a technical topic.

    In summary ...

    JPEGS are good for small file sizes, but suck if you need to do heavy editing on them.

    TIFFs are good for preserving all the detail and have good support from most packages.

    RAWs give you the most flexability, but they need to be "decoded" before anything can be done with them.

    Personally I don't ever use TIFFs as PSD (Photoshop's native format) does the same thing and is generally smaller.

    With regard to your dynamic range issue - I wouldn't worry too much - as you're going to cut it down to around 6 stops (or less anyway) (or "compress it into" might be better a choice of words).

    Also - for what it's worth - you could get 9.6 out of a properly exposed single capture on most cameras, without needing HDR.

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    arith's Avatar
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    Re: What is Tiff

    Quote Originally Posted by Colin Southern View Post
    Oops - sorry Unfortunately it's a bit of a technical topic.

    In summary ...

    JPEGS are good for small file sizes, but suck if you need to do heavy editing on them.

    TIFFs are good for preserving all the detail and have good support from most packages.

    RAWs give you the most flexibility, but they need to be "decoded" before anything can be done with them.

    Personally I don't ever use TIFFs as PSD (Photoshop's native format) does the same thing and is generally smaller.

    With regard to your dynamic range issue - I wouldn't worry too much - as you're going to cut it down to around 6 stops (or less anyway) (or "compress it into" might be better a choice of words).

    Also - for what it's worth - you could get 9.6 out of a properly exposed single capture on most cameras, without needing HDR.
    Cheers Colin, I think. I'm not fazed by technical anything; I just want to know what it is? 16 bit or 8 bit.

    Well that is important because if it is 16 bit I don't have to clone out dead pixels; saving me time since you can't see most of them, 3 but it they are a devil to find.


    What is Tiff; I still don't know. I saved a file as Tiff from 'Helicon Filter' and then got it back again to put one of my stupid borders on; and it aid 16 bit Tiff. but when I save from my camera it said 8 bit Tiff.

    So if you know where the technical stuff is please direct me in that general direction. cheers

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    Re: What is Tiff

    Yes it makes sense now I re-read it. Tiff is 16 bit but some DR is lost.

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    Re: What is Tiff

    Quote Originally Posted by arith View Post
    So if you know where the technical stuff is please direct me in that general direction.
    You'll be sorry

    http://partners.adobe.com/public/dev...tiff/TIFF6.pdf

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    Re: What is Tiff

    TIFF can be either 8 or 16 bits, maybe that's the origin of the confusion.

    However I wouldn't say RAW is a flexible format Colin. RAW cannot be defined as flexible IMO, it is simply a data container good enough to store Bayer data, but useless for any other purpose (since it cannot be saved back). RAW developmet is flexible, not the format itself.

    RAW means for every pixel we have just one colour channel (either R, G or B), and its value is encoded in usually 12 or 14 bits.
    (16-bit) TIFF means for every pixel we have all 3 channels and each of their values are encoded in 16 bits.

    Regards

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    Re: What is Tiff

    Quote Originally Posted by _GUI_ View Post
    However I wouldn't say RAW is a flexible format Colin.
    Perhaps "potential" may have been a better choice of word. By "flexible" I was meaning a format that offered the most forward options in terms of data potential (JPEG would be the opposite).

    Sorry for the confusion.

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