Sunday, September 18, 2011

What Image Format is Best for My Photography?

One of the most asked questions by new users of Nikon DSLR cameras is "Which image format should I use?"  The three most common formats are JPEG, TIFF, or NEF (RAW).

Let’s look at each of these image quality formats and see which you might want to use regularly. Following this section is a special supplement called Image Format Pros and Cons. This special section goes beyond just what formats are available and discusses why you might want to use a particular format over another. It discusses details you should know as a Nikon-using digital photographer.

NEF (RAW) Format

This Nikon proprietary format stores raw image data directly to the camera’s memory card in files and can easily be recognized since the file name ends with NEF. This is not an image format used in day-to-day graphical work (like JPEG) and is not yet really even a usable image. Instead, it’s a base storage format used to store images for conversion to another format like JPEG, TIFF, PNG, or EPS.  NEF stores all available image data and can be easily manipulated later.

The included “in-the-box” Nikon CD contains the Nikon Software Suite® for both Macintosh® and Microsoft Windows® computers. It provides Nikon ViewNX®, which can be used to examine your NEF (RAW) files in detail, and convert them to other formats. Optional software like Nikon Capture NX2® is excellent for converting your NEF files, and is my personal favorite.  Or you could purchase Adobe Lightroom®, or Adobe Photoshop® to later change your RAW files into a format like TIFF or JPEG. There are also several other after-market RAW conversion applications available, such as Bibble® or Capture One®.

Before you go out shooting in the NEF RAW format, why not install your conversion software of choice, so that you’ll be able to view, adjust, and save the images to another format when you return?

You may not be able to view NEF files directly on your computer unless you have RAW conversion software installed. Some operating systems provide a downloadable “patch” or “codec” that lets you at least see NEF files as small thumbnails. Do a Google search on these specific words, and you’ll find Microsoft® patches for NEF file viewing: “Microsoft raw thumbnail viewer download” and “NEF codec download.” You’ll be able to download codecs that Microsoft operating systems can use to display small NEF file “thumbnails” when you view a folder containing them. At the time of this book’s writing I could find only codecs for 32-bit Windows XP® and Vista®. There should be one available for Microsoft Windows 7® very soon, or maybe it will natively work with the NEF format.

There are also third-party companies, such as Ardfry Imaging, LLC that offer various 32 and 64-bit codecs for a small fee. I bought the Ardfry version for my computer. If you’re running 64-bit Windows Vista or Windows 7, you may want to check out the Ardfry Imaging people, or do a little research to see what else is currently available for viewing NEF files as thumbnails in Windows or the Mac.

On a side point, the CD included with your camera also has Nikon Transfer®, a program that helps you get your images off of the camera and onto your computer. I really like Nikon Transfer since it helps me transfer pictures to my computer and leave them on my memory card too. Then if I take more pictures on the same memory card, Nikon Transfer will only transfer the new ones when I reconnect to the computer. In a sense, Nikon Transfer acts like a one-way, memory card to computer synchronizer. As memory cards get bigger and bigger, I can see a time when I’ll keep several months of images on my camera’s card, and transfer the newest ones I take to the computer. I shot about 100 gigabytes of pictures last year. I just saw an ad for a SanDisk 64 gigabyte CF memory card—so it looks like that time is drawing near.

Nikon ViewNX RAW conversion software is supplied free with Nikon DSLRs, while Nikon Capture NX2 requires a separate purchase. Capture NX2 has become my favorite conversion software, along with Adobe Photoshop. I use ViewNX to look at my images because it has an excellent browser-type interface and then push them to Capture NX2 for final post-processing. If I need to remove an ugly spot in the sky from the edge of an otherwise spotless image or a blemish from a person’s face, I’ll use Photoshop’s Clone and Healing tools

JPEG Format

Nikon DSLRs have three JPEG modes. Each of the modes affects the final quality of the image. Let’s look at each mode in detail:

  • JPEG fine (Compression approximately 4:1)
  • JPEG normal (Compression approximately 8:1)
  • JPEG basic (Compression approximately 16:1)

Each of the JPEG modes provides a certain level of “lossy” image compression. Lossy means that JPEG throws away image data. The human eye compensates for small color changes quite well so the JPEG compression algorithm works great for viewing by humans. A useful thing about JPEG is that one can vary the file size of the image (via compression) without affecting quality too badly.

JPEG fine (or Fine Quality JPEG) uses a 4:1 compression ratio so there is a large difference in the file size, with it being as small as 25% of the original size. In this mode an image can be compressed down to as little as 4 or 5 megabytes, without significant loss of image quality. If you decide to shoot in JPEG, this mode will give you the best quality JPEG your camera can produce. Where a 10-12 megabyte compressed RAW setting only allows 500-600 images on an 8-gigabyte memory card the JPEG fine setting raises that to over 1000 files.

JPEG normal (or Normal Quality JPEG) uses an 8:1 compression ratio. This makes the image file about 2 or 3 megabytes. The image quality is still very acceptable in this mode, so if you are just shooting at a party for an average 4x6 printed image size, this mode will allow you to make lots of images. An 8-gigabyte card will hold over 2000 JPEG normal image files.

JPEG basic (or Basic Quality JPEG) uses a 16:1 compression ratio, so the image file size drops to about 1 or 2 megabytes. Remember, these are full size files. If one is shooting for the web, or just wants to document an area well, this mode has sufficient quality. My camera can store a whopping 4000 to 5000 JPEG basic files on my 8-gigabyte SD card.

Combined NEF and JPEG shooting (two images at once)

Some shooters use a clever storage mode whereby the camera takes two images at the same time. NEF (RAW) + JPEG basic is what it’s called (or RAW+B). The camera makes a RAW (NEF) file and a JPEG file each time you press the shutter button. My camera’s storage drops to about 400 images on its 8 GB memory card, since it’s storing a NEF and a JPEG file at the same time for each picture taken.

You can use the RAW file to store all the image data, and later to post-process it into a masterpiece, or you can just use the JPEG file immediately, and later work on the RAW file for high-quality purposes.

There’s no need to go into any detail about these modes other than what we’ve already discussed. The images from the NEF (RAW) + JPEG basic mode has the same features as their individual modes. In other words, the NEF (RAW) file works in a NEF + JPEG just like a NEF (RAW) file if you were using the standalone NEF (RAW) mode. The JPEG in a NEF + JPEG mode works just like a standalone JPEG shot without a NEF (RAW) file.

TIFF Format

The TIFF mode is probably the least used image quality mode on Nikon DSLRs, since it drops storage capacity on an 8-gigabyte card to just a little over 200 images. Plus, it slows the image writes to the memory card. Most of the lower cost Nikon DSLRs don't even support the TIFF format.

Personally, I would rather shoot in NEF (RAW) mode, since I can get almost double the number of images (at 12-bit color depth) on my CF card, and they are 12 or 14-bits instead of the TIFF mode's 8-bits.

However, since the TIFF mode creates images that do not have to be post-processed later (but easily can be if desired) some people will use TIFF mode for initial shooting. TIFF is not a lossy compressed mode, although there is a conversion from 12 or 14-bit to 8-bit initially. The image loses 4 or 6 bits during the conversion so there is color data loss, but it is not enough to make a big difference in the image. Use TIFF mode if you do not want the "lossy" compression of a JPEG and you'd rather not adjust the images later in your computer.

Now, let’s consider which of these formats might become your favorite and the benefits each might bring to your photography.

Image Format Pros and Cons

There are many discussions in Internet camera forums on the subject of “Which is the best image format?” In order to decide which format you may frequently use, why not examine the pros and cons of each? This section is designed to do just that. We’ll examine the pros and cons of the three formats available in many Nikon DSLRs, NEF (RAW), JPEG, and TIFF.  If your camera only supports NEF (RAW) and JPEG, please ignore the TIFF information.

Nikon Electronic Format Features — NEF (RAW)

I am a NEF (RAW) photographer about 98% of the time. I think of a RAW file like I thought of my slides and negatives a few years ago. It’s my original image file that must be saved and protected. Some concerns I can think of for the RAW format are that:

  1. You must post-process and convert every image you shoot into a TIFF or JPEG. (or other viewable format)
  2. There is no industry standard RAW image format, and Nikon has the option of changing the internals of the NEF (RAW) format each time they come out with a new camera. They usually do!

Other than those drawbacks, I and many others, shoot NEF (RAW) for maximum image quality.

It is important that you understand something very different about NEF (RAW) files. They’re not really images — yet. Basically, a RAW file is composed of black-and-white sensor data and camera setting information markers. The RAW file is saved in a form that must be converted to another image type to be used in print or web.

When you take a picture in RAW the camera records the image data from the sensor, and stores markers for how the camera’s color, sharpening, contrast, saturation, etc. are set, but does not apply the camera setting information to the image. In your computer’s post-processing software, the image will appear on screen using the settings you initially set in your camera. However, they are only applied in a temporary manner for your computer viewing pleasure.

If you don’t like the white balance you selected at the time you took the picture, simply apply a new white balance and the image will be just as if you had used the new white balance setting when you first took the picture. If you had low sharpening set in-camera and change it to higher sharpening in-computer, then the image will look just like it would have looked had you used higher in-camera sharpening when you took the image. You can change sharpening levels in the Picture control you have selected.

This is quite powerful! Virtually no camera settings are applied to a RAW file in a permanent way. That means you can change the image to completely different settings and the image will be just as if you had used the new settings when you first took the picture. This allows a lot of flexibility later. If you shot the image initially using the Standard Picture Control, and now want to use the Vivid Picture Control, all you have to do is change the image to the Vivid Picture Control before the final conversion, and it will be as if you used the Vivid Picture Control when you first took the picture. Complete flexibility!

NEF (RAW) is generally used by individuals concerned with maximum image quality and who have time to convert the image in the computer after taking it with the camera. A conversion to JPEG sets image markers permanently, while a conversion to TIFF sets the markers, but allows you to modify the image later. Unfortunately, TIFF format has very large file sizes.

Here are the pros and cons for NEF (RAW) format:


NEF (RAW) Positives

  • Allows the manipulation of image data to achieve the highest quality image available from the camera.
  • All original detail stays in the image for future processing needs.
  • No conversions, sharpening, sizing, or color rebalancing will be performed by the camera. Your images are untouched and pure!
  • Can convert to any of the other image formats by using your computer's much more powerful processor instead of the camera processor.
  • You have much more control over the final look of the image, since you, not the camera are making decisions as to the final appearance of the image.
  • 12-bit or 14-bit format for maximum image color data.
 NEF (RAW) Negatives
  • Not compatible with the publishing industry, except by conversion to another format.
  • Requires post-processing by special proprietary software as provided by the camera manufacturer or third-party software programmers.
  • Larger file sizes (so you must have large storage media).
  • No accepted industry standard RAW format. Each camera manufacturer has its own proprietary format. Adobe® has a RAW format called DNG (Digital Negative) that might become an industry standard. We'll see!
  • Industry standard for printing is 8-bit files, not 12-bit files.

JPEG Format Features

JPEG (Joint Photographic Experts Group) is used by individuals who want excellent image quality, but have little time or interest in later post-processing or converting images to another format. They want to use the image immediately when it comes out of the camera, with no major adjustments.

The JPEG format applies whatever camera settings you have chosen to the image when it is taken. It comes out of the camera ready to use, as long as you have exposed it properly and have all the other settings set in the best way for the image.

Since JPEG is a “lossy” format, one cannot modify and save it more than a time or two before ruining the image from compression losses. However, since there is no post-processing required later, this format allows much quicker usage of the image. A person shooting a large quantity of images, or who doesn’t have the time to convert RAW images, will usually use JPEG. That encompasses a lot of photographers.

While a nature photographer might want to use RAW, since he has more time for processing images and wringing the last drop of quality out of them, an event or journalist photographer may not have the time or interest in processing images, so he’ll use JPEG.

Here are the pros and cons of using JPEG mode:

JPEG Positives

  • Maximum number of images on camera card and later in computer hard drive storage.
  • Fastest writes from camera memory buffer to memory card storage.
  • Absolute compatibility with everything and everybody in imaging.
  • Uses the industry printing standard of 8-bits.
  • High-quality first use images.
  • No special software needed to use the image right out of the camera. (No post-processing)
  • Immediate use on websites with minimal processing.
  • Easy transfer across Internet, and as e-mail attachments.

JPEG Negatives

  • JPEG is a "lossy" format, which means that it permanently throws away image data from compression algorithm losses as you select higher levels of compression (fine, normal, basic).
  • You cannot use JPEG to manipulate an image more than once or twice before it degrades to an unusable state. Every time you modify and resave a JPEG image it loses more data.

TIFF Format Features

Finally, let's consider the TIFF format. It is used by those who want to be able to work with their images over and over without throwing away data from compression, like JPEG does.

You can shoot in TIFF if your camera supports it and you'll get excellent 8-bit images. When you shoot TIFF the camera does not compress the image. It does apply the camera settings to the image file immediately. Since the camera shoots natively in 12-bit or 14-bit, there is some initial data loss in using the TIFF format since some data is thrown away when converting down to 8-bit TIFF. The primary problem with TIFF files is that they are huge and will slow your camera down while it saves those large TIFF files.

Here are the pros and cons of the TIFF format:

TIFF Positives

  • Very high image quality.
  • Excellent compatibility with the publishing industry.
  • Is considered a "lossless" format, since the image normally uses no compression, and loses no more data than the initial conversion from 12 or 14-bits to 8-bits in the camera's software.
  • Can modify and resave the images an endless number of times without throwing away image data.
  • Does not require software post-processing during or after download from camera, so the image is immediately usable.

TIFF Negatives

  • Very large files in camera memory, so your ability to take a lot of images requires very large CF storage cards.
  • Must have larger hard drives on your computer to store these huge image files. 
  • In-camera image processing is slower, so you will be limited in the number of fast pictures you can take. 
  • Unless you have a high-speed Internet connection, don't even consider sending one of these monsters across the Internet. Even then, you may find you are constrained by your ISP’s file-size limitations.


Final Image Format Ramblings

Which format do I prefer? Why, RAW, of course! But, it does require a bit of a commitment to shoot in this format. The camera is simply an image capturing device, and you are the image manipulator. You decide the final format, compression ratios, sizes, color balances, picture controls, etc. In RAW mode, you have the absolute best image your camera can produce. It is not modified by the camera, and is ready for your personal touch. No camera processing allowed!

If you get nothing else from this section, remember this... by letting your camera process the images in ANY way, it is modifying or throwing away image data. There is only a finite amount of data for each image that can be stored on your camera, and later on the computer. With JPEG mode, your camera is optimizing the image according to the assumptions recorded in its memory. Data is being thrown away permanently, in varying amounts.

If you want to keep virtually all the image data that was recorded in the image, you must store your originals in RAW format. Otherwise you’ll never again be able to access that original data to change how it looks. RAW format is the closest thing to a film negative or a transparency that your digital camera can make.
That’s important if you’d like to use the image later for modification. If you’re a photographer that’s concerned with maximum quality you should probably shoot and store your images in RAW format. Later, when you have the urge to make another JPEG or TIFF masterpiece out of the original RAW image file, you will have ALL of your original data intact for the highest quality.

If you’re concerned that the RAW format may change too much—over time—to be readable by future generations, then you might want to convert your images into TIFF, DNG, or JPEG files. TIFF is best if you want to modify them later. I often save a TIFF version of my best files just in case RAW changes too much in the future. I’m not overly concerned, though, since I can still open my 2002 NEF (RAW) files from my old Nikon D100 in Nikon Capture NX2. Why not do a little more research on this subject and decide which you like best.

(This article is a short excerpt from Mastering the Nikon D300.)

Keep on capturing time...
Digital Darrell

4 comments:

  1. your post is so good.thanks for taking time to discus this topic.
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  2. Excellent report, Thanks. Disadvantages of RAW ,as I see it , would be that you have to buy the programs and even more important it ties one to the computer more. As it is , retired at 65, I am planning a schedule to get away from the computer to get in more walking, fresh air, relaxation and essential exercise in at my age.
    Thus I favour TIFF , I use Canon, but I have an old but good Nikon D100 in my camera pressthat does TIFF . Otherwise I'll use medium format film on the Bronica and Mamiya. Best Regards, Michael McGrath, Ireland.

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  3. Finally! I've looked for 15 minutes all over the internet to find an article to weigh the pros and cons, and differences of NEF(RAW) vs JPG. Thank you!

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  4. This is a really wonderful explanation of the advantages and disadvantages of raw vs jpeg vs tiff. Thank You!

    ReplyDelete