Tweet
We all use digital images at some point in our lives, many of us use them everyday. How much do you actually know about the formats you are using when you save your images? What does it all mean? So many acronyms!
To start things off all formats fall under two basic categories: Lossy and lossless. Also raster and vector, but we wont go into that here.
Lossy
Lossy compression algorithms take advantage of the inherent limitations of the human eye and discard information that cannot be seen. Most lossy compression algorithms allow for variable levels of quality (compression) and as these levels are increased, file size is reduced. At the highest compression
levels, image deterioration becomes noticeable. This deterioration is known as compression artifacting. The most common lossy format is JPEG
Lossless
Lossless compression algorithms reduce file size with no loss in image quality, although compression ratios are generally weak so file sizes are larger. Most images destined for print, or when image quality is valued above file size, are compressed using lossless algorithms.
The most common lossless formats are TIFF GIF PNG
Now what this all means is that when you save a picture as a JPEG you lose data. How much data is lost depends on the compression setttings you select, but any time you save as a JPEG you lose some data. JPEG has its advantages because its file sizes can be very small and are ideal for the web. Every time you re-save a JPEG you lose more data! Now if you save a picture as a TIFF or PNG you dont lose any data, but your file may be very large.
So when you save your images it is important to make a decision based on these guidelines.
To start things off all formats fall under two basic categories: Lossy and lossless. Also raster and vector, but we wont go into that here.
Lossy
Lossy compression algorithms take advantage of the inherent limitations of the human eye and discard information that cannot be seen. Most lossy compression algorithms allow for variable levels of quality (compression) and as these levels are increased, file size is reduced. At the highest compression
levels, image deterioration becomes noticeable. This deterioration is known as compression artifacting. The most common lossy format is JPEG
Lossless
Lossless compression algorithms reduce file size with no loss in image quality, although compression ratios are generally weak so file sizes are larger. Most images destined for print, or when image quality is valued above file size, are compressed using lossless algorithms.
The most common lossless formats are TIFF GIF PNG
Now what this all means is that when you save a picture as a JPEG you lose data. How much data is lost depends on the compression setttings you select, but any time you save as a JPEG you lose some data. JPEG has its advantages because its file sizes can be very small and are ideal for the web. Every time you re-save a JPEG you lose more data! Now if you save a picture as a TIFF or PNG you dont lose any data, but your file may be very large.
So when you save your images it is important to make a decision based on these guidelines.
Comment