Week-3 Image Types, Styles, and Usage

Image Types, Styles, and Usage

5 Types of Digital Image Files:

1. TIFF
   1. Tagged Image Files
   2. Very large, uncompressed, detailed image data
   3. Extremely flexible
   4. Most common used in photo software (photoshop), layout software (InDesign)
2. JPEG
   1. Joint Photographic Expert Group
   2. Has been compressed -> Small size
   3. Loses some image details
   4. Used in photograph on the web
   5. Bad for line drawing and logo -> bitmappy
3. GIF
   1. Graphic Interchange Format
   2. Compressed, no detail lost, not as small as JPEG
   3. Limited color range, suitable for web, but not for printing
   4. Used in animation
4. PNG
   1. Portable Network Graphic
   2. Replace GIF -> owned by one company -> nobody wants to pay licensing fees
   3. Allows full range colours and better compression
   4. For web images, not printing
   5. Larger than JPEG -> Less bitmappy
   6. Most screenshots are PNG
5. Raw material files
   1. Have not been processed
   2. Each camera often has its own proprietary format
   3. Extremely large, converted to TIFF before editing

 

Other Digital Image Files:

1. PSD
   1. Created and saved in Photoshop
   2. Contain layers -> easy to modify
2. Raster (Bitmap)
   1. Made of certain number of pixel (JPGs, GIFs, PNGs)
   2. Defined by proportion (High or Low)
   3. Pixels stretched -> not fit -> blurry/unclear image
   4. It is important to save Raster files at the exact dimensions needed for the application
3. Vector
   1. Based on mathematical calculation (.eps, .ai, .pdf, and .svg)
   2. Perfect for creating graphic that require frequent resizing
   3. Great ability to be sized from small and huge

 

High vs Low Resolution

DPI -> Dots per inch

PPI -> Pixels per inch

Used to determine if density of pixels in an image is appropriate for the application.

Website display images at 720dpi (low), print image require 300dpi

 

Alpha Channel

• a Mask
• Specifies how the pixels colours should be merged with another pixel when the two are overlaid, one on top of the other
• Typically alpha channel defines as an object

Common Web image size

• Should be in a positive balance file size (mb,kb) and dimension (pixels)
• Too big -> Will not be loaded very quickly
• Too small -> Compromising the quality