One of the quirks of the DCP format is that the actual image that ends up written to the DCP must be in one of two ratios — 1.85:1 or 2.39:1 — and no other (with some obscure exceptions that we don't need to worry about).
This means that the image size in the DCP will be one of the following:
| Ratio | Name | Picture size for 2K | Picture size for 4K |
|---|---|---|---|
| 1.85:1 | Flat | 1998 x 1080 | 3996 x 2160 |
| 2.39:1 | Scope | 2048 x 858 | 4096 x 1716 |
If your video is already in one of these ratios, things are easy: DCP-o-matic will scale your image to the required size. You just need to select either ‘DCI Flat’ or ‘DCI Scope’ from the DCP Video tab in DCP-o-matic.
If your video is not in one of these ratios, you have three choices:
In most cases doing nothing is the best idea. There is nothing bad or unusual about having black bars at the sides or top and bottom of your DCP. Even if you did make a 1.78:1 DCP it would do nothing to change the size or shape of the cinema screen.
Here is an image which is 1920x1080 pixels, so its ratio is 1.78:1 (sometimes known as ‘HD’).
You could crop it or stretch it to fit a DCP, but almost certainly the best thing is to choose the closest ratio and then do nothing else. Here the closest DCP ratio to our image is 1.85:1 (‘Flat’). Choosing that in DCP-o-matic will give a DCP which looks like this:
Your image is the same ratio as it was before; DCP-o-matic just added some padding. This is standard practice when making DCPs from 1.78:1 sources, will look fine in the cinema, and does not distort nor crop your image. If you have an attentive projectionist they may even move some masking curtains to cover the black bars.
Here is an image which is 1440x1080 pixels, so its ratio is 1.33:1 (sometimes known as ‘Academy’ or 4:3).
Once again, the best thing to do here is to choose the closest ratio and then do nothing else. Here the closest DCP ratio is once again 1.85:1 (‘Flat’). Choosing that in DCP-o-matic will give you:
As before, DCP-o-matic has padded your image. Once again, this is standard practice when making DCPs from 1.33:1 sources.