A Comparison of the Different File Formats on Your DSLR

If you are new to DSLR photography you may have been confused about the one or two additional image formats that exist on these cameras. Perhaps you have been using a DSLR for a while but have never considered switching to another format because of the mystery concerning their benefits. You see no problems with your present images so why would you want to change. A little knowledge of the different image formats along with their benefits and drawbacks can result in a more satisfying experience in your pursuit of better photography.

The CCD (charge-coupled device) and the CMOS (complementary metal–oxide–semiconductor) are the two most common sensors used in digital cameras today. The CCD is an analog device that stores the light as an electrical charge within the sensor. This electrical charge is then converted into digital information as part of the camera system. The CMOS uses a semiconductor technology to convert the light readings to digital code. This requires additional circuitry within the sensor itself. Neither CCD nor CMOS have any clear advantage in their usage.

The Bayer sensor is the cheapest and most common in digital cameras today. The pixel sensors on this unit detect only one of the three prime colors: red, green and blue. The individual color pixels are placed in a grid patter across the face of the image sensor. There are twice as many green pixels as there are red or blue. In order to produce the other colors the sensitivity of the light is determined from the surrounding pixels and adjusted accordingly. The result is a digital code that represents the combination of the red, green and blue sensors to produce the color desired.

The digital color information can be represented as 256 colors (8-bit), 4096 colors (12-bit), 16,384 colors (14-bit) or 65,536 colors (16-bit), depending on the make and model of your camera system. Printers generally use 8-bit color information to produce photographic prints.

Joint Photographic Experts Group (JPEG) is the committee that established the qualifications for this image standard in 1992. Since then it has become the most popular format for photography. Practically all camera systems will create photographs in this format and it is the accepted form by most purchasers of photographic images.

Camera images can require a substantial amount of memory space to store photographs, especially with the newer cameras exceeding 10 megapixels. The main advantage to the JPG format is that it compresses the data to enable it to take up less memory. However, this comes at a cost. JPG uses what is referred to as a lossy compression, that is, in the process of reducing the size of the image file it loses a certain amount of data that cannot be retrieved. Compression ratios can vary with a subsequent smaller file size but greater data loss. This results in image deterioration. But what must be kept in mind with JPG is that there is no post-processing needed. All adjustments to sharpness, color saturation, white balance, etc. are accomplished in the camera.JPG is best used with photographs and art where there are smooth transitions between tone and color. Line art, text and similar images may cause problems for the JPG format due to the high contrast between adjacent pixels resulting in artifacts (distortions). These types of images are better rendered in TIFF (Tagged Image File Format), GIF (Grafic Interchange Format), PNG (Portable Network Graphics) or RAW (Unprocessed camera data, called NEF (Nikon Electronic Format) on Nikon cameras) formats.

TIFF (Tagged Image File Format) is a file format that was originally designed for desktop publishing applications. It is widely used by graphic artists and photographers due to its flexibility and adaptability. Since 2009 the TIFF format has been under the control of Adobe Systems.

Unlike JPG images, TIFF is a lossless (no data loss) form of file storage. As a result, the image can be manipulated and saved without affecting the original sensor data. There are some drawbacks however. Although TIFF can employ some form of compression, the files are far more bulky than their JPG counterparts. TIFF files are generally saved in a 16-bit format resulting in a much larger storage requirement.

A few high-end DSLRs will allow images to be saved in the TIFF format. It is best to check your owner’s manual to see if your system has that option. If not, RAW images can be converted to TIFF using post-processing software.

Raw data files, sometimes called digital negatives, contain the unprocessed data directly from the camera sensor. Raw information is typically 12-bit or 14-bit as directly read from the individual pixel sensor. It takes the role of the negative in the modern DSLR.

There are many benefits to using raw data over other formats. These include but are not limited to:

• · Higher image quality
• · No image data loss
• · Greater image control
• · More intensity information due to the 12-bit or 14-bit values
• · Color space can be set to values other than specified by the camera
• · More data availability

One of the main disadvantages of raw data is that it always requires some form of post processing. Before the image can be viewed it will have to be changed using a raw converter. This data can then be manipulated within the post processing software to adjust sharpness, color, contrast, brightness, etc. Once these changes have been made the image can be saved in various formats such as JPG, TIFF, PNG, and others. However, the raw data retains the original sensor data and can be manipulated further if desired. This is known as non-destructive processing. As long as the original raw file is available the photograph can be changed as many times as the user wishes.

Depending on the make and model of your camera system, there are several image file formats available. There are definite advantages and disadvantages to each format. If you have no post processing software, JPG is the only route to go. If, however, you have a decent post processor, some of the other file formats can provide an unlimited opportunity to express your artistic aspirations.

Originally posted on my blog at the following address: http://www.technowdigest.com/2010/12/comparing-different-file-formats-on.html

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