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Thread: RAW and JPG : an overview

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    Administrator ricktas's Avatar
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    RAW and JPG : an overview

    What is RAW?

    First off, RAW should really be written as raw, but for the sake of this thread, I am capitalising it to make it stand out.


    You may have heard mention of this thing called RAW, well what is it exactly? The RAW file format for digital photos is named after the fact it is basically the raw data captured from the camera's sensor and saved onto your memory card.

    RAW files are big, compared to JPG files (see the JPG section below), so photographers who shoot in RAW will need to consider bigger memory cards, more hard-drive space. RAW files are proprietary, so the file extension will vary depending on your brand of camera. Some of the file extensions for RAW are : *.dng, *.raw, *.nef, *.raf,*.orf, *.srf, *.sr2, *.arw, *.k25, *.kdc, *.dcr, *.mos, *.pnx,*.crw, *.cr2, *.tif,*.mrw, *.pef, *.mef

    Some of the benefits to the photographer of shooting in RAW are:
    * Higher image data quality
    * White balance can be adjusted in post processing
    * Bypasses in camera sharpening, noise reduction, colour saturation etc
    * The data is 12 or 14 bits (generally) whereas JPG is 8 bit
    * Colourspace is not set and can be altered in post processing.

    So a RAW file contains direct data captured from the camera's sensor, unprocessed. Leaving it up to the photographer to process the photo on their computer and thus gives them direct control over all aspects of how the photo data is manipulated. RAW files are often referred to as a Digital Negative.

    What is JPEG/JPG

    JPEG is an acronym and it stands for Joint Photographic Expert Group, the file type is usually reduced to JPG. The format was created to allow the compressions of photographic image data into smaller sizes to permit smaller files, and thus allow for easier transmission over the internet, between computers. JPG files are typically much smaller file size wise, than RAW files. JPG files are 8bit.

    JPG files are a lossy file format. This means that when a JPG file is repeatedly saved it loses data each time. The JPG format is designed to maximise file size savings, thus repeated saving of the same file will see image quality degradation, eventually making the file very pixelated and probably useless to use.

    Some of the benefits to the photographer of shooting in JPG are:
    * Smaller file sizes, needing less space on memory cards and hard-drives
    * JPG files have adjustments automatically applied to them 'in camera', often including sharpening, noise reduction and colour saturation adjustments, meaning often there is less post processing needed.
    * JPG files can be easily emailed, uploaded to the internet, due to smaller file size.
    * The Colourspace is defined and set (usually sRGB)

    Processing RAW

    RAW files require special software called Raw Converters to be able to view the data contained within them. There are many Raw convertors available, and camera manufacturers will usually supply a free one with your camera (on disk, or for download), that specifically works with the RAW file extension that your camera produces. Raw Convertors are also available from third party suppliers. Products like Adobe Lightroom, Apple Aperture are able to read RAW files for most camera formats.

    Raw convertors allow the user to change the white balance, exposure, highlight and shadow adjustments and more, all in a loss-less environment, meaning that data is not lost from the RAW file when each adjustment is applied. A RAW file can be re-processed over and over, with no loss of quality.

    There is a tutorial here on processing RAW files, but you would need to undertake some study into using your own Raw converter software, to make the most of using it.

    Often photographers will use the Raw Converter software to make 'whole of image' adjustments, then move into photo editing software for other changes.

    Processing JPG

    JPG files are already processed when you take them off your memory card and place them onto your computer. What has been done during that processing depends on how you have set your camera up, but generally saturation, Colourspace and sharpening have already been applied.

    Processing a JPG file can be done in any photo editing software (Photoshop, Elements, Paint Shop Pro, Picasa, Gimp and more). It is often worth treating your JPG file straight off the computer as a Digital Negative also. Save it, and then make a second copy, always work on the second copy, cause each time you save a JPG file the lossy compression will degrade the quality of the file. At first you may not notice any degradation, but after repeated editing and saving, your file may become severely degraded to the point of not being worth using. In need, you can go back to your original (digital negative) version, create another copy and start again.

    JPG files often require less post processing than RAW files due to the in-camera adjustments that have already been applied.

    Links:

    More about RAW
    More about JPG

    Ultimately, it is up to each person to decide which file format they want to use, then set their camera up for it. But to chose the right format for you, will require some reading and understanding of what each format does and its benefits and limitations.
    Last edited by Kym; 26-01-2010 at 6:41am.

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    Thanks for that Rick
    Cat (aka Cathy) - Another Canon user - 400D, 18-55,75-300mm Kit Lens,50mm f1.8, Tamron 90mm f2.8 Macro, Sigma 28-70 f2.8-4 DG, Tripod and a willingness to learn
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    very interesting, thankyou

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    That's great information Rick, thanks.

    I shoot everything in 14 bit RAW these days, jpeg is not an option
    at all. After reading a thread here about a month ago where members
    were saving an image as raw & jpg in camera I thought it was worth
    doing the exercise. It's interesting how different the two images are
    straight out of the camera.

    I am doing more processing in Adobe Camera Raw these days before
    taking it into Photoshop, also the beauty of it is being able to revisit the
    image in ACR and change any of the adjustment made prior.

    It's hard to appreciate at first the advantages of shooting in raw until you
    want to make adjustments to a jpeg file and find out how restricted
    you are.

    An honest C+C please!


    "I started life with nothing and I still have most of it left"

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    Member mikeyman's Avatar
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    Thanks for that Rick i never new that jpgs degrade with saving.
    Being a beginner this sort of info is really helpful for me cheers..

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    Never stop learning GerryK's Avatar
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    Thanks Rick. I did a photoshop course at CAE this time last year and the guy taking it really bagged raw, indicating that Photoshop could do all that raw processing could. I think he was telling half the story.

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    Quote Originally Posted by GerryK View Post
    Thanks Rick. I did a photoshop course at CAE this time last year and the guy taking it really bagged raw, indicating that Photoshop could do all that raw processing could. I think he was telling half the story.
    Just goes to show you teaching from a text book is not as effective as having "real" experiences to share.

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    Ausphotography Regular Jeanette's Avatar
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    sorry going to ask a very newbie question
    i am saving in jpg and raw on my camera and i get the jpg and NEF files on my transfer.
    but they wont go in to photoshop
    what am i doing wrong .. if some kind person can explain

    thanks again for your information ... i am learning so much on my first day here
    cheers Jeanette

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    Quote Originally Posted by GerryK View Post
    Thanks Rick. I did a photoshop course at CAE this time last year and the guy taking it really bagged raw, indicating that Photoshop could do all that raw processing could. I think he was telling half the story.
    I think he wasnt even on the same page. Anybody that suggests that with a JPEG that you can "do all" that you can do with a RAW is either delusional, or just stupid, or both

    I would have stood up and demanded my money back right there and then
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    question, when i take a picture at night using my flash (cannon 430) the raw pictures come out with a natural colour where as jpeg images cause a redish skin colour on people. Any reasons for this?

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    white balance most likely!! but could be any other reason too.

    camera settings such as vividness contrast etc.

    Are these shots that you're comparing shot in raw and jpg(at the same time) or only one type shot in camera individually at different times.

    Auto Whitebalance(AWB) can be both accurate and innacurate in the same conditions with successive shots. Always try to choose an appropriate WB setting when shooting jpgs.
    Nikon D800E, D300, D70s
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    {Tamron}; -> 17-50/2.8 : 28-75/2.8 : 70-200/2.8 : 300/2.8 SP MF : 24-70/2.8VC


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    Thanks for that info, very interesting

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    Quote Originally Posted by Jeanette View Post
    sorry going to ask a very newbie question
    i am saving in jpg and raw on my camera and i get the jpg and NEF files on my transfer.
    but they wont go in to photoshop
    what am i doing wrong .. if some kind person can explain

    thanks again for your information ... i am learning so much on my first day here
    cheers Jeanette
    It is probably the version of the RAW converter you have. What camera do you have and what version of PS?

    Roo
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    It's all about the Light!
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    Quote Originally Posted by GerryK View Post
    Thanks Rick. I did a photoshop course at CAE this time last year and the guy taking it really bagged raw, indicating that Photoshop could do all that raw processing could. I think he was telling half the story.
    How dumb is that?

    Raw gives you 4 or 6 bits more data than JPEG, about a stop or more dynamic range.
    Not to mention better control of white balance etc.
    Plus raw is not a lossy format. JPEG by design loses data.
    Sure, you need to do more work with raw in your workflow; but you get much more for that effort.

    Based on facts this guy is a goose!

    Not to say there are not times to use JPEG (eg. some sports or other high frame rate scenarios), but raw is the default for important work.

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    good article. thanks Rick. i find raw is easier to process when needed although most of the time this is only half of process. raw is the way to go.
    Regards,
    Agi

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    Why compress data until you really need too? If you're machine can process it fast enough and has enough capacity to store it, shoot it!

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    And the clincher for me is the huge range of tones in RAW compared to jpeg. Why throw away about 75% of the data your DSLR is capable of capturing?

    Odille

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    That's a bit misleading whoever made that table though.

    An 8 bit JPG file can represent 16777216 distinct colours
    A 12-bit file can represent 68719476736 distinct colours

    That's a 0.0244140625% difference... not 75%

    Even going by the table it's a 5% difference, not 75

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    I just threw together my own table to maybe explain my above post better

    Untitled-1.jpg

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    Something very wrong with the maths here!!
    Greg

    Please feel free to rework any of my images on this forum.

    I also welcome any constructive criticism or suggestions.

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