SYGADC: RAW vs. JPEG, Photoshop vs. Photoshop Elements, Stabilization, Exposure, and White Balance

Review:

• Common camera problems
• Digital SLR's
• Megapixels

RAW vs. JPG/JPEG:

• JPEG is the default format used by almost every digital camera ever made. Named after its developer, the Joint Photographic Experts Group (and pronounced "jay-peg") this format lets you specify both image size and compression. The smallest size is best for the Web and e-mail (although it will usually have to be reduced) and the largest for prints.
• The JPEG format compresses images to make their files smaller, but many cameras let you specify how much they are compressed. This is a useful feature because there is a trade-off between compression and image quality. Less compression gives you better images so you can make larger prints, but you can't store as many images. Because you can't add pixels as well or remove the effects of compression after the fact, it's usually best to use the largest size and least compression. If you have to reduce either, you can do so later in a photo-editing program.
• To get the highest possible quality, you want to start with the best possible score— a RAW image file. These files contain all of the image data captured by the camera's image sensor without it being processed or adjusted. You can interpret this data any way you want instead of having the camera do it for you. If you want total control over exposure, white balance, and other settings, this is a format you will learn to love. 
• Only four camera settings permanently affect a RAW image— the aperture, shutter speed, ISO, and focus.  (memories of the Pentax K-1000...)  
• Other settings may affect the appearance of the thumbnail or preview but not the image itself. Since each camera company has defined its own proprietary RAW format, many operating systems and even photo-editing programs are unable to recognize some or all of these files. If the camera supports the RAW format the camera manufacturer always supplies a program along with the camera.
• With many cameras you can capture RAW images by themselves or with a companion JPEG image that gives you an identical high quality RAW file and a smaller, more easily distributable image file. Both the RAW and JPEG files have the same names but different extensions.

Advantages of Using the Raw Format:

1. RAW lets you decide on most settings after you've taken the picture, not before. For example, when you shoot a JPEG image under fluorescent lights, the camera adjusts the image to remove the yellow-green tint. Any changes you make later are on top of this initial change. If you shoot the image in RAW format, the camera just captures the images as is and you decide what white balance setting to use later. You can even create different versions of an image, each with its own white balance.
2. RAW images aren't compressed using a lossy compression scheme that throws out data to make image files smaller. Although some cameras have a compressed RAW format, these images are compressed using lossless compression. When you open these images, they contain all of the original image data.
3. RAW images aren't processed in the camera as JPEG images are. When you take JPEG photos, a processing chip with the power of a small computer manipulates them based on the camera settings you have used and then compresses them to reduce their size. The changes made to your images cannot be undone later because it's the final, altered image that is saved in the image file. Some of the original image data is lost for good. With RAW images, all of the original data captured by the camera is saved in the RAW image files so you can process them later on your computer. The settings used to take RAW images are saved, but they are not permanently applied to your images until you save a version of them in another format such as JPEG or TIFF.
4. RAW images have greater color depth and that gives you smoother gradations of tones and more colors. For example, JPEG images use only 8 bits per color (RGB) or 24 bits total.
5. Meanwhile many RAW images are initially captured by the sensor in 48 or 36 bit RGB (16 or 12 bits per channel) and only reduced to 24 bit RGB (8 bits per channel) when converted into JPEG files. The full 48 or 36 bits are retained in the RAW file after the images are processed on your computer because the original file isn't overwritten with your changes. You can even retain all 16 or 12 bits per color by saving images in a format such as TIFF or Photoshop's PSD format.
6. RAW images can be processed again at a later date when new and improved applications become available. Your final image isn't permanently altered by today's generation of photo-editing applications.
7. You can use a RAW image to generate alternate versions of the same image. For example, many photographers will adjust highlight and shadow areas and save these versions separately. Using a photo-editing program, they then combine the two images and by selectively erasing parts of the top image let areas of the lower image show through so all areas have a perfect exposure.

Disadvantages of Using the Raw Format:

• RAW files in the camera are quite large. If you use this format a great deal you will need more storage space in the camera and computer and processing times will be longer.
• Since RAW images aren't processed in the camera, you have to process them on the computer. When you are done shooting for the day, there is still work to do. You need to convert them to another format when you want to e-mail them, post them on a Web site, print them, or import them into another program to create a slide show or publication. Many cameras help you get around this by simultaneously capturing JPEG versions at the same time they capture RAW images. You can use these more universally supported images for many of your applications and reserve the high quality RAW versions for when you need the highest possible quality.
• RAW images are not always noticeably better. Where they shine is when you have exposure or white balance problems. Because RAW images have 16 or 12 bits per color instead of the 8 bits used by JPEG's you have dramatically more information to work with when making adjustments.

RAW and Photoshop CS5 or the less-expensive, Photoshop Elements:

• http://www.adobe.com/products/photoshop/cameraraw.html
• http://www.adobe.com/products/photoshopel/
• http://www.digicamhelp.com/processing-photos/advanced-editing/photoshop-elements-7-vs-photoshop-cs4/ 

Image Stabilization:

When you move the camera during an exposure, especially at slow shutter speeds, when shooting close-ups, or using a long focal length lens, it causes blur in the image. To reduce this blur, some cameras have image stabilization systems. These systems use a sensor to recognize camera movement and then try to compensate using a variety of techniques. The process goes under a confusing variety of names including image stabilization, vibration reduction, and anti-shake.

• Optical image stabilization works by moving a prism in the camera or an element in the lens to redirect the light path to compensate for the unintended movement. The camera moves one way, and the prism or lens element moves the other. This is the most effective method, but also the most expensive.
• Digital image stabilization shifts the image on the sensor to compensate for motion. When this technique is used, not all of the sensor's pixels can be used for the image. Some of those on the border have to be reserved for the shifting image projected by the lens. Another digital technique is to process the captured image to try to remove the blur.
• Pseudo image stabilization just increases the ISO so the camera can select a faster shutter speed.

When the camera has a fixed lens, it doesn't matter which approach is used. However, on cameras with interchangeable lenses it does matter. If the system resides within the camera body it will work with any lens, if it resides within the lens it only works with special lenses. When thinking about image stabilization, keep in mind that it's always been available in the form of a tripod, monopod, beanbag, or a flat surface on which to rest the camera. You can increase stability by using the self-timer or remote to reduce vibrations.  Steady yourself!

Exposure Modes - The Camera's Choices:

Digital cameras have various ways of controlling the aperture and shutter speed. All modes give equally good results in the vast majority of photographic situations. However, when you photograph in specific kinds of situations, each of these exposure modes may have certain advantages. Here are modes you may want to look for although it can be complicated by the way camera companies use different names for the same things.

• Automatic mode sets the shutter speed and aperture without your intervention. This mode allows you to shoot without paying attention to settings so you can concentrate on composition and focus.
• Scene modes, which go by a variety of names, have preselected settings for specific situations such as landscapes, portraits, night portraits, sports, and close-up photography. On some cameras the number of these settings has gotten a bit out of hand since there are so many you have to select them from a menu.
• Shutter-priority mode lets you choose the shutter speed you need to freeze or deliberately blur camera or subject movement and the camera automatically sets the aperture to give you a good exposure. You select this mode when the portrayal of motion is most important. For example, when photographing action scenes, such as those encountered by wildlife photographers, sports photographers, and photojournalists, shutter-priority mode might be best. It lets you be sure your shutter speed is fast enough to freeze the action or slow enough to blur it.
• Aperture-priority mode lets you select the aperture needed to obtain the depth of field you want and the exposure system automatically sets the shutter speed to give you a good exposure. You select this mode whenever depth of field is most important. To be sure everything is sharp, as in a landscape, select a small aperture. The same holds true for close-up photography where depth of field is a major concern. To throw the background out of focus so it's less distracting in a portrait, select a large aperture.
• Manual mode lets you select both the shutter speed and the aperture. You normally use this mode only when the other modes can't give you the results you want. Some cameras have a bulb setting in this mode that lets you capture time exposures such as light trails at night. In this mode the shutter remains open as long as you hold down the shutter button. If it's open for more than 1 second, noise in the form of randomly-spaced, brightly-colored pixels may appear in the photograph. To reduce noise at slow shutter speeds, turn on noise reduction if the camera has it.
• Custom settings mode on high-end cameras lets you store personal settings. If you use the same settings over and over again it may be worthwhile saving them for future use. Some cameras let you save one or more sets and then instantly access them at any time just by turning a mode dial. Storing your own settings is as simple as setting the camera the way you want it and then selecting the menu's command that assigns them to the custom setting.

White Balance:

• White balance (WB) is the process of removing unrealistic color casts, so that objects which appear white in person are rendered white in your photo. Proper camera white balance has to take into account the "color temperature" of a light source, which refers to the relative warmth or coolness of white light. Our eyes are very good at judging what is white under different light sources, but digital cameras often have great difficulty with auto white balance (AWB) — and can create unsightly blue, orange, or even green color casts. Understanding digital white balance can help you avoid these color casts, thereby improving your photos under a wider range of lighting conditions.

Incorrect White Balance	Correct White Balance

		Auto White Balance
		Custom
		Kelvin
		Tungsten
		Fluorescent
		Daylight
		Flash
		Cloudy
		Shade

• Fortunately, most digital cameras contain a variety of preset white balances, so you do not have to deal with color temperature and green-magenta shift during the critical shot. 
• The first three white balances allow for a range of color temperatures. Auto white balance is available in all digital cameras and uses a best guess algorithm within a limited range.
• Custom white balance allows you to take a picture of a known gray reference under the same lighting, and then set that as the white balance for future photos. With "Kelvin" you can set the color temperature over a broad range. 
• The remaining six white balances are listed in order of increasing color temperature, however many compact cameras do not include a shade white balance. Some cameras also include a "Fluorescent H" setting, which is designed to work in newer daylight-calibrated fluorescents. 
• The description and symbol for the above white balances are just rough estimates for the actual lighting they work best under. In fact, cloudy could be used in place of daylight depending on the time of day, elevation, or degree of haziness. In general, if your image appears too cool on your LCD screen preview (regardless of the setting), you can quickly increase the color temperature by selecting a symbol further down on the list above. If the image is still too cool (or warm if going the other direction), you can resort to manually entering a temperature in the Kelvin setting.  
• By far the best white balance solution is to photograph using the RAW file format (if your camera supports them), as these allow you to set the WB *after* the photo has been taken. RAW files also allow one to set the WB based on a broader range of color temperature and green-magenta shifts. 
• Performing a white balance with a raw file is quick and easy. You can either adjust the temperature and green-magenta sliders until color casts are removed, or you can simply click on a neutral reference within the image. Even if only one of your photos contains a neutral reference, you can click on it and then use the resulting WB settings for the remainder of your photos (assuming the same lighting). 
• A neutral reference is often used for color-critical projects, or for situations where one anticipates auto white balance will encounter problems. Neutral references can either be parts of your scene (if you're lucky), or can be a portable item which you carry with you. Below is an example of a fortunate reference in an otherwise bluish twilight scene.

• On the other hand, pre-made portable references are almost always more accurate since one can easily be tricked into thinking an object is neutral when it is not. Portable references can be expensive and specifically designed for photography, or may include less expensive household items. An ideal gray reference is one which reflects all colors in the spectrum equally, and can consistently do so under a broad range of color temperatures. An example of a pre-made gray reference is shown below:

• Common household neutral references are the underside of a lid to a coffee or pringles container. These are both inexpensive and reasonably accurate, although custom-made photographic references are the best (such as the cards shown above). 
• Certain subjects create problems for a digital camera's auto white balance — even under normal daylight conditions. One example is if the image already has an overabundance of warmth or coolness due to unique subject matter. The image below illustrates a situation where the subject is predominantly red, and so the camera mistakes this for a color cast induced by a warm light source. The camera then tries to compensate for this so that the average color of the image is closer to neutral, but in doing so it unknowingly creates a bluish color cast on the stones. Some digital cameras are more susceptible to this than others.

• A digital camera's auto white balance is often more effective when the photo contains at least one white or bright colorless element. Of course, do not try to change your composition to include a colorless object, but just be aware that its absence may cause problems with the auto white balance. Without the white boat in the image below, the camera's auto white balance mistakenly created an image with a slightly warmer color temperature.

• Multiple illuminants with different color temperatures can further complicate performing a white balance. Some lighting situations may not even have a truly "correct" white balance, and will depend upon where color accuracy is most important.

• Under mixed lighting, auto white balance usually calculates an average color temperature for the entire scene, and then uses this as the white balance. This approach is usually acceptable, however auto white balance tends to exaggerate the difference in color temperature for each light source, as compared with what we perceive with our eyes. 
• Exaggerated differences in color temperature are often most apparent with mixed indoor and natural lighting. Critical images may even require a different white balance for each lighting region. On the other hand, some may prefer to leave the color temperatures as is.