Aspect ratio examples

[SteveLLamb]

To add to https://registry-page.isdcf.com/projectoraspectratios/

Either as example of different active image aspects or as official values (as used in the metadata):

@palemieux @japierce1028, Thoughts? This would cover our "other" ratios.

[JBoisseau-ByDeluxe]

These are examples of aspect ratio, I'm sure people will suggest some more.

As the list could be endless, I suggest to also clarify the method to compute a resolution from an aspect ratio.

Here is the method I suggest:

A- convert the "Aspect Ratio 'name' " to an actual fraction/rational, if there is a documentation.

1.37 = 1.37
1.33 = 4/3
1.77 or 1.78 = 16/9
2.0 = 2.0 ?
1.66 = 1.66 exactely ?
2.66 = 2.66 exactely ?

B- apply the fraction to the container
-> 16/9 applied to 1998x1080 = 1920x1080
-> 2.0 applied to 1998x1080 = 1998x999

C- round the resolution to the upper even. because ST429-16, 5.4.2.13, says that height/width shall be multiples of two
-> 1998x999 becomes 1998x1000

NB:
This algorithm and the table above intentionnally doesn't answer the question of "the most appropriated container for my specific ratio".

[JBoisseau-ByDeluxe]

Addendum:
I think the main question to solve is the rounding method.

I see 2 scenario, that still produce an even number:

A- Rounding to the upper even (as suggested above)
B- Rounding to the lower even

There are pros and cons,

Let's consider the final picture in these Flat and Scope containers is the result of a resize, probably executed by the post-house.
Depending on the algorithm, if the final resolution is not round/even, the resize will produce "soft edges", half transparent lines on edges.

for instance:
2.0 applied to 1998x1080 = 1998x999.
If centered, it produces a half transparent line on top, a half transparent line at the bottom.

if A: 1998x1000, half transparent lines will stay and screened as is.
if B: 1998x998, half lines be cropped out, (ideally during the mastering, or by the projector, if it has a 2.0 macro)

I think that sharp edges is preferable, the B scenario

Here is table with the B option applied

In addition, I think we should recommend to apply the crop during the mastering stage, so the CPL Metadata / ActiveArea resolution perfectly matches the actual active area in the Picture.

What do you think ?

[JBoisseau-ByDeluxe]

Addendum n°2:
2K vs 4K.

In above tables, 2K and 4K resolutions are computed independently.
-> The 4K resolution may not be strictly the 2K x2.

pros: the 4K ratio is closer to the original ratio, than the 2K ratio
cons: a 4K DCP played back as 2K will have an even number of lines/columns.

I think we all expect a 2K projector to receive the same 2K resolution from a player, whatever the DCP is 2K or 4K (played back as 2K).

So I suggest this revised method:

• the above algorithm to compute a resolution only applies to 2K resolution
• a 4K resolution must be the 2K resolution x2

Here a revised table: