PNG, JPG, GIF, and TIFF—Oh MY!  By Jennifer Walling

PNG, JPG, GIF, and TIFF are just a few of the commonly-used graphics file formats. Without a basic understanding of what each type actually is, which type to use when can be pretty confusing.

At the most basic level, image or graphic files are split into two types—vector based and bit-mapped based.

Vector formats use geometry to represent the image, while bit-mapping uses dots arranged in patterns (much like pointillism does in fine art). Bit-mapping can also be referred to as rasterization. The main difference to keep in mind between the two is that bit-map images are resolution-dependent, and when they are printed or viewed on larger monitors, they generally look better at higher resolutions. Vector graphics are not resolution-dependent, they tend to have a smaller file size, and they scale (resize, stretch, etc.) better. Most paint programs (e.g., Adobe Photoshop, Corel Painter) manipulate images using bit-mapping methods, whereas drawing programs (e.g., Adobe Illustrator, Corel Draw) generally use vector formulas.

The four main styles of image file formats (online and off) are GIF, JPEG, PNG and TIFF. They differ mainly in how the file is compressed when it is saved. Some formats are ‘non-lossy,’ while others are ‘lossy.’ Lossy file formats will lose bits (pixels) as they save the file, since they are designed to delete/erase bits that do not affect the image visually. Due to small file size, these types of files can be great for web use. However, they are bad for constant changes and re-saves of an image, because the file loses information with each save. Think of making a copy from a copy from copy from a copy on a photocopier. The image degrades more and more with each generational copy out from the original.

Click here to read the entire article.