One of the most useful image formats is JPEG (short for Joint Photographic Experts Group), which uses a .jpg file extension. JPEG compresses files to create a smaller size file. On a digital camera a "quality" setting sets how much compression is used when saving the file. The levels are often referred to as fine, normal and basic. These settings are associated with a compression ratio.
The higher the level of compression you choose, the smaller the size of the file. The drawback to this compression is that every time the file is saved again, a small amount of image quality is lost. This method is similar to making a photocopy of a photocopy of a photocopy. Each successive copy is slightly reduced in quality from the original. If the image is going to be edited and saved numerous times, then another file format such as Tagged Image File Format (TIFF) should be used for the interim saves of the file. The TIFF file format is lossless, it does not lose image quality in exchange for a smaller file size, but it also does not compress files, so files are larger and require more space to store. Note: A new image format JPEG 2000 is rapidly gaining support and this allows for 'lossless' compression i.e. an image can be saved multiple times without loss of quality.
Estimate of Image Capacity
||Number of images
1) Some of your cards listed capacity is used for formatting and other functions and hence is not available for image storage.
2) Please note these are estimates only and are for standard JPEG images. The JPEG file sizes will vary depending not only on your camera model and its default settings, but also the compression mode settings and the subject matter in your photos.
|MP=Megapixels: 1 Megabyte (MB) = 1,000,000 bytes; 1 Gigabyte (GB) = 1,000 Megabytes
The file sizes and number of images stored on memory are an average only. As is the case with JPEG it's difficult to predict the size of an image because it will vary a fair amount depending on the content of the image (especially the amount of detail captured). For example, take a photograph of a fairly empty wall and you'll get a small JPEG, take a photograph of a crowd of people with a lot of detail and you'll get a larger image. Different camera manufacturers also use slightly different compression ratios and different terms for describing them.