Digital File Types

 

 
The Basics from Your Digital Camera

Digital photography has reached a remarkable level of beauty and sophistication. The output from today's digital cameras are capable of reproducing an amazing range of color, subtleties of tone and detail. This is even more remarkable given the fact that, at their essence these images are nothing more than collections of million of sterile little zeros and ones. This week I want to briefly discuss how those digits are stored in image files and how the choice of the file type can affect the results of the final image.

The Basic Choice, Lossless vs Lossy 
There is a long list of image file types that are available, but only a few which are routinely used to record images within todays digital cameras. Most commonly these include JPEGs (.jpg), TIFFs (.tif) and various versions of RAW files. The choice of file type centers around two factors, image quality and file size and as is true for almost all of photography, the decision involves compromise. The highest quality image files (TIFF and RAW) record the photographic data with what is referred to as "Lossless"
algorithms that retain all of the information from the sensor. The resulting images are of higher quality, with optimal tonal range and less noise and they are less subject degradation during editing or copying. The only disadvantages of lossless images are their requirement for editing to reach their full potential and their substantial size. TIFFs and RAW images fill memory cards quicker and take longer to save. The longer save times becomes a significant issue when capturing bursts of images such as when shooting wildlife or sporting events.

JPEG Have Trouble with High Contrast Situations

The opposite of "lossless" are those file types that achieve smaller files by compressing and discarding the data. These are somewhat

JPEGs struggle to Salvage Detail in Shaddows

comically referred to as "lossy". Within digital cameras, JPGs are the primary example of this compressed format. JPEG algorithms reduce file size by throwing out data and reducing the tonal depth. Depending on the level of compression, the results are files which are much smaller, allowing quicker recording of bursts of images and room for more pictured on the memory cards, but there is a significant price to pay for the compression. JPEGs and other Lossy file types have poorer tonal range with higher noise and artifact. They stand up much less well to aggressive editing or repeated copying. Depending on the image's intended usage, this loss of quality may not be important, but, as we will see, it is important to understand how the choice of original file type affects your ability to reach your photographic goal.

Those are the basics, now let's look at the individual file types.

Lossless Files

Doing It in the RAW

Capt. Zerubbabel's Rest

Many, but not all digital cameras have the capability of recording images in "RAW" format. RAW files record the "naked" data from the sensor without any loss of tonal depth or color information. They are totally unedited within the camera, although the image that you see on the LCD screen is actually a JPEG rendered within the camera to allow for quicker display and a better sense of how the final image might look. RAW images are like film negatives. They contain the maximum amount of information from the sensor, providing the greatest capability to undergo editing and adjustments of brightness and color balance. RAW files are substantially larger than compressed formats, but given the inexpensiveness of memory and the greater processing speed of modern cameras, this is not a major disadvantage.

Capt Zerubbabel Snow returned to Chesterfield after fighting in the Revolutionary War
He died in 1795 and lies next to his father, John Snow, in the West Burying Grounds.
"Winter is Coming !"

 Perhaps the RAW file's greatest disadvantage comes as a consequence of its greatest advantage. The down side of the format's ability to be manipulated is that RAW files must be edited to reveal their true beauty. Unedited "raw" RAW files appear flat with low contrast and washed out colors. All the glorious potential is there but it must be brought forth in post-processing. For me this is he most exciting part of working with RAW files. It is akin to the darkroom magic of watching prints slowly appear from the developer bath, but if you want to snap the picture and be done, then RAW is not for you. All I can say is that if the quality of your images is important to you, then learning to work with RAW images is unarguably worth the effort.



Whose RAW is It Anyway?
There is no single RAW format. Each camera manufacturer has their own proprietary format and provides the software required to
edit it. Lightroom, Photoshop and many other photo editing programs can read

Spring Sentinel, Keene, NH

most of these formats, but every time Canon or Nikon comes up with a new camera or wrinkle in their format, the software companies have to scurry to catch up. The persistent question is, if a camera company disappears or looses interest, will support for their RAW files vanish as well. For this reason Adobe has created their own open source RAW format called Digital Negative ".dng". My standard workflow involves archiving the proprietary RAW files in a separate directory and then converting the files to DNGs that I use as my working images. It may sound complicated, but, happily, Lightroom can do it all automatically as I upload the files from my memory card.

TIFF
Tiff files might be more appropriately discussed among the various "output" file types, used to store and transmit images after processing, but some cameras have the option of recording images

Persistent Maple

in this format. TIFF (Tagged Image File Format) files are often used to store images since the image files are Lossless. Like RAW files, they retain all the information on brightness, contrast, color balance and saturation, but unlike proprietary RAW formats, TIFFs are universally accessible to essentially all editing software. TIFFs come in 8 and 16 bit versions with the same quality advantages in the 16 bit files. When used to save files edited in Photoshop, TIFF files have the ability to retain most of the layers created by that program, but this capability comes with a cost in file size. TIFFs can be gigantic, but this is less of an issue when the file is coming unedited directly from the camera. For me TIFFs are primarily useful when I want to send an easily readable, full resolution, edited image to a friend or client. When I want to record losslessly in the camera, I stick to RAW.

Lossy Files
 
JPG
JPG stands for Joint Photographic Expert Group and is the most

Central Square Gazebo, Keene, NH

common file type, found in essentially every digital camera. Again it uses a lossy algorithm to record image data into compressed files. JPEGs undergo processing within the camera including "Baking in" the color balance based on the camera settings. The resultant images can often look better than unprocessed RAW images, but this preprocessing limits the ability to make adjustments during editing in Lightroom or Photoshop. The level of compression of the JPG file can be adjusted, but in all cases the resulting images are reduced in tonal depth, usually from the RAW 12-16 bits to only 8. 8 bit images have only 256 tonal gradations for Red, Green and Blue as compared to more than 64,000 with 16 bit images. This difference may not be apparent in small images

RAW or JPEG, Makes Little Difference on the Web

designed for sharing on the internet, but it becomes strongly evident when they are manipulated in Photoshop or other programs, resulting in loss of detail, color banding and restriction of the ability to enlarge the image. Despite the loss of quality, JPEG is a popular format because the images come out of the camera requiring little if any processing to get an acceptable picture and because the image files are much smaller making them easier to store and to share.

The Quality Shows with Bigger Images

Size Matters
A full resolution, 21 megapixel RAW file coming from my Canon 5D Mark II is 25.8 megs in size compared to only 6.1 megs for a 21 megapixel maximal resolution JPEG. This means that more than four times as many JPEGs than RAW files can be stored on any memory card. It also means that, with the JPEG files, I can shoot a burst of 78 images before the camera will be forced to pause in order to buffer the data. In RAW I am limited to only 13 images in a burst. The choice of higher levels of JPEG compression has further impact on both the file size and image quality. At the highest degree of compression the file size drops to one megapixel, but, at a resolution of only one meg, image quality severely suffers.

Dancing Lady.  When trying to anticipate the action, JPEGs allow longer bursts of images.
For only the second time in years of shooting Stonewall Farm's "Dancing of the Ladies",
I caught a lady in full kick.

 

 

 

The Choice
It really comes down to what you want to do with the image after it leaves the camera. Modern digital cameras are remarkably sophisticated and, in unchallenging situations, do an excellent job

Many cameras can record image in two formats

recording images in JPEG. If your only goal is to grab that picture of the ham sandwich you had for lunch, and transmit it as quickly as you can, to as many people on the internet as possible, then JPEG is the way to go. If your goal is to go beyond the mere FACT of the image, and explore the remarkable quality and capabilities of modern digital photography, then RAW is the ONLY choice. And, when the situation arises, during post-processing, you can always compress that delicious RAW ham sandwich into the tiny JPEG that it truly deserves.

Jeff Newcomer
partridgebrookreflections.com

White Balance, The Basics of Digital Photography

  
Taking the Light's Temperature
 
Photography always comes back to the light and the color of the light that illuminates our subjects exerts a profound effect on the resulting image. Visible light can vary from the orange of candle flame to the deep blue of the evening sky, but he human eye has a remarkable ability to compensate for this wide spectrum. We can recognize a white card as being white through a broad color range, but our digital cameras lack our cognitive abilities to interpret visual input. Without correction, a white object captured in the yellow light of an incandescent bulb will be recorded with a yellow tint and the blue sky, illuminating someone in the shade of a building will change the face to a cold sickly blue. Digital cameras offer auto white balance settings (AWB) , using various algorithms to compensate for changes in the color of light, but, as is true of most automatic settings, the adjustments often don't produce the best results. This is one of those situations where the computer in your brain can work better that your camera's microprocessor, so its time to get to work.

Your Light Has a Temperature

Specturm of Light
http://www.exposureguide.com/white-balance.htm

Most digital cameras have white balance settings to adjust for a number of the common colors of illumination. These may work better than the Camera's auto white balance, but the balance is fixed and won't change with changing light. Fortunately a glance at the camera's LCD screen can provide quick feedback about the effect of any selection. The common presets include:

 
Sunlight:
Unfiltered sunlight contains the full spectrum of visible light and as a result tends to produce the most accurate white and color reproduction. This is a good setting when shooting outside in full sunlight, but who actually does that?

Cloudy and Shade:
In both of these situations the light tends to be cooler, as the full

Abigail in Full Shade

spectrum is filtered through blue clouds or comes into shaded areas from the even bluer sky. Cloudy and Shade settings compensate by warming the image. The Cloudy setting provides enough warming to balance the cooling effect that occurs when sunlight is scattered and filtered through the overcast. The Shade setting provides a warmer adjustment for times when the subject is illuminated by the more intense bright blue dome of the sky. It is important to be aware that, when shooting in the shade, areas outside of your main subject that are in the bright sunlight may take on an unnatural orange tint.

Tungsten:
Indoor illumination from Tungsten light bulbs has a strong yellow

Tungsten Color Balance

hue and the Tungsten setting is used to cool down the digital image by adding blue. A good way to appreciate this effect is to shoot outside in sunlight with the Tungsten WB setting. This will reinforce the importance of readjusting the white balance when you going from inside to outdoors. Last

Kissing Bridge Tungsten WB

week I used the tungsten setting while shooting inside the Vermont Country Store. When I ventured outside, I forgot to readjust the WB and the first couple images of the "Kissing Bridge" had an intensely blue tint. This blue shift is also seen when windows to the outside are included in my indoor photography. Situations like this, when there is a mosaic of different colored light, can be challenging and is where local adjustments of color balance in Photoshop can be a life-saver.

 
Fluorescent:
Fluorescent lighting has a blue/green shade which is warmed using the Fluorescent setting. The color of fluorescent can vary a good deal and it can take experimentation to find the best WB setting.

Flash WB

Flash:
The light from most flash units tends to most closely approximate sunlight, but can be a bit cool. The flash setting usually tends to slightly warm the image.

 






Custom White Balance:
The fixed white balance adjustments can provide a good approximation of the correct setting for specific lighting, but they are often imperfect. Some cameras allow fine tuning of the color compensation, but the use of Custom White Balance can be the easiest way to nail the precise adjustment. This option is available on many digital cameras.

Incandescent Light
and Tungsten White Balance

Custom White Balance starts with taking a picture of a white or neutral gray card in the same light that is falling on your subject. These cards are available on-line or at your local camera store (remember those?). A clean white piece of paper or anything else which is pure white can serve. I have a card with white on one side and gray on the other. The details vary, but on my Canon 5D II, I display the picture of my white card,

Custom White Balance

which has been exposed in the correct light and positioned in the center of the frame. Then I select "Custom White Balance" from
my camera's menu. I tell the camera to use the current image as the basis for custom white balance and then, any time I select "Custom" for the white balance option, the white balance will return to this setting. Custom white balance is helpful whenever precise control of color is necessary, such as in product photography. Your client will not appreciate getting the color wrong on the Campbell Soup can. 



 


 

Shoot RAW! 
All of this fuss about white balance is especially important if you are shooting in JPEG rather than RAW. Need I say that this is just one more reason that you should shoot in RAW? In-camera white balance settings are of little importance when shooting RAW since all of the color information is preserved in the RAW image. Regardless of the original setting, the white balance can be adjusted in post-processing without any loss of quality. Unfortunately, when shooting in JPEG, white balance is baked into the image file with the loss of a significant amount of color data.






 
 To demonstrate this, I intentionally shot Chesterfield's historic town hall with the white balance incorrectly set to tungsten. I captured the image in both RAW and in the highest quality JPEG and then tried to salvage the images to accurately reflect the overcast lighting. There was no problem readjusting the RAW color balance, but, despite doing everything I could in Lightroom and Photoshop the JPEG image's color remained disappointingly flat and dull. 




As can be seen, post-processing color balance adjustments on JPEG files are difficult and result in a poor quality image. If for some totally unfathomable reason you are still shooting in JPEG, there are two things to remember.

• First, don't.   
• Secondly, if you do, careful adjustment of white balance in the camera is essential. You really won't get a second chance.

So, when shooting RAW is there any reason to set a specific white balance? I generally keep my camera on Auto White Balance. In most situations this works well as a starting point and then I almost always tweak the color in post. In a few situations such as portraiture or product photography strict color accuracy is important, but for most of my work, precise color matching is not necessary or even desirable. When I am shooting in the golden evening light the last thing I want is for whites to appear pure white. If I used custom white balance from a white card, I would loose all the warmth of the scene. Occasionally I will use the cloudy or shade settings to more accurately reflect the warmth of the "Golden Hours", although when shooting in RAW I can make the same adjustment in post. In post processing I am looking for the colors that best reflect the appearance and feel of the moment. 

 


A Fixed White Balance
There are occasional instances when setting a specific fixed white balance can be helpful. Last week I had a great time shooting in the

Country Store Light

Vermont Country Store. The lighting came uniformly from incandescent bulbs and, by setting the camera to Tungsten White Balance, all of the images had a consistent white balance adjustment. The color wasn't precisely what I wanted, it was still a bit yellow for my taste, but, because all of the images started with the same color balance, I was able to batch all of the images together and make a single adjust which worked pretty well for all of them. Because in AWB the white balance changes from image to image, a single adjustment would not have worked as well for all of the images. Shooting in Tungsten WB ended up saving time that would have been spent performing subtle tweaks to many of the images.



Of course Photoshop and Lightroom have powerful tools to adjust

Cloudy WB

white balance in the digital darkroom, but that should be a topic for a future blog. For now it is important to understand how the camera sees color balance differently from our remarkable eyes and how color balance settings help to compensate for this difference. This is the time to settle back with your manual (if you can find it) and learn about how your camera adjusts white balance. Keep your eye on that LCD screen and experiment your brains out. Getting color balance right is especially important when shooting JPEG, but whether recording JPEG or RAW files it all comes down to Getting Color Balance Right in the Digital Camera.

Jeff Newcomer
Partridgebrookreflections.com