Different computer file types for saving images

Electronic media must be stored, well, electronically.  This means it has to be written in a format that a program can both write and read.  The kind of data (text, image, sound, video, etc) is one important factor.  A file for text cannot hold graphical information and a sound recording cannot on its own manage a database.  

Software creating, saving, and reading files is done through recognition of a file type.  The three letter code at the end of a file, preceded by a period, denotes the file format.    For images, there are a half dozen common formats that are used including jpeg, tiff, heif, and a few others.  Typically, you see these as .jpg, .tif, . heif, and so on.  

Digital images are saved by using pixels, tiny blocks that are used to create pictures.  An image may use hundreds of thousands or millions of these pixels.  We use the term megapixel (mp) to denote how many there are in an image.  More pixels mean more detail and more options.  

The problem with saving images is that they use a huge amount of memory.  A camera producing a 12 mp image would need 36 mp of space per image if the information wasn't somehow compressed.  You could store only 2 such images on a CD.  So most graphic file types have some form of compression.  

Images basically contain two types of information.; pixel location and colour.  That information can be stored one piece of information at a time, but as previously pointed out, the non-compressed image takes up a huge amount of information.  This is what a TIFF file is.  It used to be a common file type, but it rarely used nowadays because of the amount of space it takes up.

Compressed files include the venerable JPEG and the newer HEIF formats.  They take up much less space than uncompressed files, but at a cost.  For jpegs, it means a decrease in quality because of the compression system.  We say that the file type is lossy, meaning that there is degradation of image quality.  The amount of degradation depends on how much compression there is.  Most cell phones save them at an 8:1 ratio (normal).  Non-cell cameras tend to give you a choice between 16:1 (basic), normal, and 4:1 (fine).  

Heif format is also compressed, but is lossless in nature, meaning that there is no corruption of the data.  Most cell phones offer this file type, and it is preferable to jpegs.  The trade-off is that older computers cannot open the heif files without the right software.  This can be downloaded for a minimum expense.  Newer mirrorless cameras may have heif as an option.

PNG files are made for graphics.  If you do a screen capture on your cell phone, it is saved as a png.  Pixel editing programs can both make and edit pngs.  

For serious photographers, RAW is the only viable choice because of all the manipulation possibilities.  They tend to be large files, but the raw sensor data offers unpresidented editing.  I have done many blogs on raw files in the past; you can do a search for them on my blogger site.  The great downside to raw images is that they are propriatary and can only be opened by specific software.  Each camera has its own raw file type.  There is also a modest amount of effort and knowledge required to process them.  if you are serious about quality, these lossless files offer the best options.

I shoot everything in raw on my DSLR and mirrorless cameras.  I also shoot some of my cell phone images in raw format because of the improved imagery and editing abilities.  If I don't use raw on my cellphone, I default to heif to reduce the number of artifacts.  None of my camera equipment can produce tiffs, although I have a lot of large files tucked away using that format.  

Hopefully, this information has given you something to think about.

Thanks for reading.

Eric Svendsen     www.ericspix.com