# Digital Photography/Pre-Processing

This section deals with the decisions you need to make before you take your first shots.
* The choice of compression and resolution
* the choice of manual or automatic mode

## Choice of Compression and Resolution

The primary choice you must make when choosing resolution/compression is how often do you want to change memory cards.
You should always take photos at your camera's highest resolution and with minimum compression (normally known as superfine), even if you just want photos for the web, you never know when you might take the perfect photo you want to print for posterity. With some cameras, you can store the photos in raw format. While these allow for maximum flexibility, you're unlikely to need this level of flexibility unless you want to use advanced post-processing techniques.
Memory cards have very high amounts of storage and even at high resolution, they can hold hundreds or thousands of digital images. On top of that, they are cheap and plentiful. Given that, there isn't much need to shoot photos at anything less than your highest resolution settings. If for some reason you need low resolution photos for a particular circumstance (web, e-mail, etc.), it is best to crop and down-sample your images in post-production. You will end up with much better results and have a lot more flexibility in how the final product will turn out.
All modern digital cameras are capable of saving photos in the JPEG format. This format is one of the standards for Internet bitmap graphics, the others being GIF and PNG. JPEG photos require some special considerations, however. JPEG files can suffer quality loss if re-saved multiple times in an image editor. Furthermore, JPEG photos are a highly processed format in which the user loses control over certain aspects of the photo, such as white balance. The main advantage to JPEG files is that they are highly compressed and you can store a lot of them in a given memory space.
Most DSLR cameras offer an additional mode: RAW. RAW mode requires additional post-processing by the user, often in proprietary software designed to read a given camera's RAW format. There is no one industry-standard file format for RAW pictures; each manufacturer generally has at least one proprietary format. RAW files are also extremely large compared to JPEG files; one RAW file might take up the space of five or six JPEGs. The main advantage of RAW is that the photographer or image processor has a greater degree of control over the photograph than is possible in the JPEG format. RAW pictures also don't suffer the same gradual loss of quality as JPEG pictures, unless they are re-saved into a lossy format.
Many newer DSLRs offer the option of saving pictures as both a JPEG and RAW file.

## Choice of Manual or Automatic Mode

The purpose of this guide is to help you understand what setting your camera handles when it is in automatic mode and how, by taking control of these settings, you can improve your photos.
The three most important items your camera's automatic mode controls are the flash, aperture size and exposure time (usually called shutter speed). These three all affect the lighting of images.
* The flash affects the lighting in an obvious way, but in some situations a flash will be inappropriate (for example when there is something in the shot that will reflect the flash or if you are photographing animals that will be scared by the flash).
** Specific conditions under which you would want to use a flash are:
*** Indoor photographs not requiring natural light
*** Portraits
*** Night Photography where natural light is again not important.
*** Daylight Photography when shadows are not desired on the object or person.
** Conditions under which using a flash would spoil your photographs are:
*** photographs in which you want to capture the effect of dim lights on objects, portraits, landscapes, etc.
* The aperture can be thought of as the "iris" of the camera. When the aperture is wide open lots of light gets through, so the image will be brighter. However, having a larger aperture will mean you get a narrower Depth of Field, which means a limited range of focus.
* The exposure time is the amount of time the aperture is "held open". The longer the time, the more light can be received, so the image will be brighter. However having a long exposure time has one major disadvantage, a long exposure time means motion (either on the part of the subject or on the part of the person holding the camera) is more likely to cause problems (i.e. blurring).
Now to the meat of the matter. All modern digital cameras that are not marketed as children's toys have a variety of modes. The exact specifications of each mode vary from camera to camera, but all digital cameras have a "full auto" mode in which the camera selects everything: ISO sensitivity, flash, shutter speed, aperture, color balance, and the like. Most digital cameras offer other automatic modes as well based upon common consumer uses: a high shutter speed mode for photographing athletics, a mode for taking pictures of landscapes, one for night photography, one for photographs using incandescent light, et cetera.
DSLR cameras offer additional modes which would commonly be found on a film SLR: aperture priority mode for when depth of field is important, shutter speed priority for a variety of uses such as photographing sports or timed exposures, and full manual mode where the photographer must provide both the aperture and shutter speed. While these modes may seem intimidating to an inexperienced photographer, they can provide a much greater level of control and allow a wider variety of pictures to be taken of the exact same scene than a comparable automatic mode. Some DSLRs have additional manual modes such as the A-DEP (automatic depth of field) mode on a Canon 20D; for more information on those, consult the owner's manual.
Whether you use an automatic mode or a manual mode, and which specific mode, is ultimately up to you based upon your needs and the kind of photos you want to take.