JPEG Format

JPEG, an acronym for Joint Photograpic Experts Group, is a popular file format for digital images that provides not only smaller file sizes than the RAW files, but also offers the advantage of being able to display your images straight from the camera on any computer, on the web, and in e-mail messages. To achieve the small file size, JPEG compresses images, and in the process, discard some data from the image typically data that you would not easily see. This characteristic of discarding image data during compression is why JPEG compression. High compression level, the smaller the file size and the more images that you can store on the memory card, and vice versa.

As the compression level increases to make the file size smaller, more of the original images data is discarded, and the image quality degrades. Compression also introduces defects, referred as artifacts, which can create a blocky, jagged look, blurring, and diminished color fidelity in the image. At low compression levels, artifacts are minimal, but as the level increases, they become more noticeable and objectionable. You'll see the effects of high compression ratios when you enlarge the image to 100 percent in an image - editing program on the computer. To get the highest - quality images, use the lowest compression and the highest quality settings, such as Large/Fine. If space on the card is tight, then use the next lower setting, Large/Normal. If you use lower quality settings, just be aware that the image quality diminishes accordingly.

TIPS: If you edit JEPG images in a editing program, image data continues to be discarded each time you save the file. I recommend downloading JPEG files to the computer, and then saving them as TIFF (Target Image File Format) or PSD (Photoshop's file format) files. TIFF and PSD, available in Adobe's Photoshop image- eiditing program, are lossless file formats.

When you shoot JPEG images, the camera's internal software processes, or edits, the images before storing them on the memory card. This images processing is an advantage if you routinely print images directly from the SD card, and if you prefer not to edit images on the computer. And because the T3i/600D offers a variety of Picture Styles that change the way that image contrast, saturation, sharpness and color are rendered, you can get very nice prints with no editing on the computer.

The JPEG quality option reflect the megapixels recorded of image. At the Large settings, images are recorded at 18 megapixels. The Medium quality option record megapixels, while Small quality option record 4.5 megapixels.