In past times, photographs would be captured onto light sensitive film. Then, after development in the darkroom, a negative would be produced. With digital photography, images are stored as a digital file. For viewing, the file is decoded – and there are 3 main types of file used – JPEG, TIFF and RAW.
Before we look at these file types, it is pertinent to explain the difference between “lossy” and “lossless” files. When a picture is taken, the camera records the data onto the memory card as a file. If all of the data is stored, this is known as a lossless file. These files are large in size. RAW files are lossless. To reduce file size, the camera can discard part of the data not easily perceptible to the human eye. A JPEG is a lossy file. A TIFF file is, in principle, a flexible format that can be lossless or lossy.
JPEG the most common file format used by amateur photographers, mainly because so many pictures can be recorded on one card. Whilst the actual number will vary depending on the camera used, it is possible to take over 1500 images using just one 2GB memory card.Because this is a lossy file, the images are compressed.
This results in a greater amount of pictures possible when compared to lossless files. The camera will allow you to set the level of compression, so more, or less, photos can be taken. Just bear in mind that the overall quality will be affected the more compressed the file. So, if you were looking to print images above standard sizes, you would need to choose less compression.
These files take data straight from the camera’s sensor. This means they are not processed by the camera at all and represent the purest image, as taken. They are sometimes referred to as a “digital negative”. Using the optimum (i.e. least) compression level, you could expect to record just 100 images, or less, on a 2GB card, using a 15megapixel camera. The major plus here is that you will be able to produce high quality prints of A3 size and over. Professionals and serious amateurs use RAW files.
Unlike JPEGs, RAW files are not universal across different manufacturers. For example, Canon uses the term RAW, whilst Nikon’s equivalent are known as NEF files. These are not compatible with each other. However, each manufacturer will supply software with the camera to enable you to process and print the images. RAW files are excellent for post production image manipulation, because all of the original data is still intact, and can therefore be worked with.
In practice, TIFF is generally used as a lossless file format that uses no compression. Consequently, file sizes can be large, but retain their data, and subsequent quality. However, the file size is huge when compared to the identical JPEG file. A common use of TIFF is as a working format for editing digital images in Photoshop, or equivalent. With JPEG editing, slight degradation occurs with each new file save. TIFF is lossless, if no compression is selected, so there is no loss of quality each time a file is amended and saved.
TIFF should not be used for displaying images on the web, because of file size. Most web browsers will not display a TIFF image.
Hopefully this beginner photography article has helped to clarify the difference between the file formats. In summary, if ultimate quality and large printing is not required, JPEG files will more than suffice, and can also be used on the internet. RAW files are excellent for serious photographers who want the maximum quality, and ability to make detailed changes in post production. These files can be amended to TIFF or JPEG when ready. TIFF files do not lose quality (if uncompressed) so are good for working on in post production, before final saving as a JPEG.