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ARC130S SECTION
6
ARC130S 060801 Version 1 Issue 1
6.4
Abbreviated Explanation of Aspect Ratio Technical Codes for Video and Picture Sources
(For full details see Section x, Appendix 2)
These codes can used to describe the aspect ratios used when graphics or video sources are composed or
generated. They describe the image and the raster ratios.
Code Specification:
Code format is thus:
AABCCD
Where
AA
is the first parameter,
B
is the second
etc.
The four parameters of the code must used in the
order specified. Not all parameters have to be
used if not appropriate or known, however
B
(The
Display Format)
should be present to prevent
ambiguity.
AA
Active Image Aspect Ratio -
Number(s)
Aspect Ratio of Active Image Area expressed as a
two digit abbreviated numeric value where the
comparison ratio is against a height of 9. Active
Image area is the part of the raster / bitmap that
contains picture information. 12 is normally used
for 4 by 3 (12 by 9).
ie.
Two digit number giving the aspect ratio of the
picture area that viewers are interested in, that is
neglecting any areas of continuous and static black
due to letter-boxing or pillar-boxing. Numbers
describing ratios seen in use at present are: 12,
14, 15 (Super 16), 16, 17 (1.85:1), 21 (2.35:1), 24.
Thus 14 : 9 becomes
14
.
B
Display Format - Letter
The visual effect of the image and display raster
aspect ratios combined. Abbreviated as an initial.
P
for pillar-box.
That is full height but with
black down the sides.
L
for letter-box.
That is full width with
black top and bottom.
F
for full frame.
Display and Image aspect
ratios are the same.
i.e. if it’s purely in letter box presentation put in an
L
etc. e.g.
14
L
12A -
”14 by 9 letterbox for..”. This
letter confirms what the pictures look like and
separates the two ratio numbers.
Note: Letter
A
has been proposed for material
converted an Anamorphic presentation - that is the
image is designed to be displayed distorted. This
can be as a result of stretching a picture to fit a
given display shape whilst avoiding cropping.
Active Image
Area