• Aspect ratio is simply the ratio of an image’s width to its height. Standard aspect ratios for film and video are sketched, to scale, in figure below.
  • Conventional standard-definition television (SDTV) has an aspect ratio of 4:3. Widescreen refers to an aspect ratio wider than 4:3.
  • Widescreen television and high-definition television (HDTV) have an aspect ratio of 16:9. Cinema film commonly uses 1.85:1 (“flat,” or “spherical”). In Europe and Asia, 1.66:1 is usually used.
  • The 2.39:1 ratio for cinema film is recent; formerly, 2.35:1 was used.
  • The term anamorphic in video usually refers to a 16:9 widescreen variant of a base video standard, where the horizontal dimension of the 16:9 image is transmitted in the same time interval as the 4:3 aspect ratio standard.
  • Film can be transferred to 4:3 video by cropping the sides of the frame, at the expense of losing some picture content.
  • With the advent of widescreen consumer television receivers, it is becoming common to see 4:3 material displayed on widescreen displays in pillar box format.
  • The full height of the display is used, and the left and right of the widescreen frame are blanked.

Reason for the choice:

1] Human eye has more movement in the horizontal direction as comapred to that of vertical horizontal.

2] The rectangular screen format gives the best viewing comgort and paranomic effect

3]For a human eye the region of maximum resolution at the center of the retina has larger area along the width as compared to its height.