Taking Pictures in the Raw or Putting on JPEG Pants—Part I


It’s the (digital) age-old question: Raw vs. JPEG.  Today and Friday we’re going to definitively answer it . . . sort of.  If you have one of the more sophisticated cameras currently on the market, particularly if you have a DSLR or one of the newer mirrorless Interchangeable Lens Cameras (ILC), your camera probably has the capability to save photographs in at least two file formats—Raw and JPEG.  The question is, which one should you be using?

First, what is Camera Raw?  Raw is an image file containing data from every single imaging pixel from the sensor in your camera.  That means these files are huge.  It also means that these files are totally unprocessed and are thus unsuited for printing or even display on your computer.  If you were to display the raw image file to your friends and family, the resulting picture would appear to be flat, lifeless, and unflattering, with dull colors and very little contrast.  On the upside your image would show a lot of detail at both ends of the spectrum, from dark shadows to brightly lighted areas (this is called an image’s “dynamic range”).  Raw files also have greater bit depth, usually in the range of 12 bits to 14 bits versus JPEG’s 8-bit depth.  What does that mean?  In simple terms it means that, while you can get nearly 16.8 million colors out of a JPEG, most raw images will give you somewhere between 68.7 billion to 4.2 trillion colors and much smoother tonal transitions . . . theoretically.  More on that later.  One thing to bear in mind here is that there is no true industry standard for the raw file format—each camera manufacturer has its format and almost none are cross-compatible.  The closest thing there is to an industry standard is Adobe’s Digital Negative (DNG) format.

So, what is JPEG?  JPEG is an industry-standard lossy image file compression scheme that was developed by the Joint Photographic Experts Group way back in 1992 and which is still in use today as the primary image format for digital photographic display and printing.  By ‘lossy,’ we mean that every time you open a JPEG file, edit it, and then save the resulting file, the resulting image will be further compressed and image data will be lost.  The more times you edit and save the worse this loss gets, eventually resulting in noticeable visual degradation in the image.  Not a good thing.  If you’re going to edit a JPEG, do it on a direct copy of the original (save that original just in case); don’t edit a copy of a copy of a copy or you’ll soon regret it because the damage is usually irreversible.  Almost every digital camera on the market has the ability to shoot in JPEG, and many cameras with raw capability will give you the ability to save images in both raw and JPEG simultaneously . . . but at the cost of eating up memory card space.  Shooting in JPEG will give your available memory cards approximately three times the capacity over shooting in raw, but shooting in JPEG+raw depletes space quickly because you’re actually saving both a JPEG image and a huge raw file for each image taken.

(A quick word of warning:  Your camera probably allows you to increase compression of your JPEG files from “fine” to “normal.”  Don’t fall for it; there’s nothing normal about “normal.”  Shooting in “normal” might increase the number of images you can store on your memory card, but it comes at the cost of losing image data that you’ll never be able to recover later should you need it.  If you’re shooting in JPEG, shoot in “Fine.”)

So, what does all this mean?  Let’s think about these two formats in old photographic film terms.  Camera raw is the color negative film of the digital world.  To be useful, you have to take the resulting negative and “process” it into a usable “print.”  And being that there’s a post-processing phase involved, raw can cover up a lot of photographic “sins” that were committed at the time you took the shot—everything from bad white balancing to even moderate corrections in exposure control can be fixed.  A JPEG file equates to color slide film, or perhaps even one of those old Polaroid Instant Cameras that spits out a picture seconds after the shot is taken.  Once the slide is developed and mounted or the Polaroid picture rolls out of the camera, you’re done.  What you see is what you took at the moment you pressed the shutter release button, and there’s not a whole lot of leeway after the fact to correct problems with the image.

Before you decide which format is better for you, let’s go back to raw for a moment.  Remember that theoretical color depth advantage?  The promised 68.7 billion or even 4.2 trillion colors over JPEG’s much more limited 16.8 million colors?  Remember that raw needs to be processed into a usable format before you can display it on a computer or print it out.  And to what image format will you ultimately be converting that raw image?  You guessed it.  JPEG.  So, that color depth advantage?  Gone.  You just converted it back to a 16.8 million color JPEG.

Well, maybe.  There’s still a way around the JPEG format that would allow you to take full advantage of raw’s significantly greater color depth advantage.  It’s yet another file format called TIFF, and we’ll discuss it Friday in Part II of Taking Pictures in the Raw or Putting on JPEG Pants.

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2 Comments

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2 responses to “Taking Pictures in the Raw or Putting on JPEG Pants—Part I

  1. – Thanks Doug. I don’t know if it’s timing or technique but that’s the clearest explanation I’ve read. Well done.

    Don Brown

  2. JJ Rohan

    Thanks from me too. Rohan