How to properly crop a 4K DCP
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friedmanme7
- Posts: 2
- Joined: Tue Sep 13, 2022 3:07 pm
How to properly crop a 4K DCP
Hi, this is my first time making a DCP so sorry if this is a silly question. I have a 4k file that was shot at 4096x2480. I don't want black bars on the side so I set it to 1:85:1 but now I need to crop the sides to make sure the image is correct. Would anyone be able to help me on this? Thank you.
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Carsten
- Posts: 2804
- Joined: Tue Apr 15, 2014 9:11 pm
- Location: Germany
Re: How to properly crop a 4K DCP
Was this shot with a specific aspect ratio in mind (e.g. framing guides)?
4096*2480 is 1.65:1, so, roughly 'the old' TV wide screen or Super 16 format (1.66:1).
Is this DCP targeted towards a specific screen (e.g. a premiere), or for a wide distribution?
When I create DCPs for our own screen, I know our screen design and I know we have side adjustable masking - so I can make the best decisions based on that specific screen, often creating non-standard aspect ratios that perfectly fit our masking. When I create a DCP for a wider release that is meant to play in a range of different cinemas, I usually create one of the two standard aspect ratios flat or scope, and, if necessary, with some letter- or pillar-boxing. Some one has to make a decision about the amount of cropping that is acceptable, and wether the cropping could be asymmetrical (e.g. more on the bottom to leave more head room).
First of all, use the latest version 2.16, as it provides better cropping and scaling options than the previous 2.14.x builds.
Flat/1.85:1 4k container is correct. You need to crop away quite a bit from the top and bottom in order to fill the flat screen without any letterboxing.
Now, without any content (active image/framing/safe frame) related concerns, I would use these parameters. But again, at roughly 130pixels crop from top and bottom, you may shift the image a bit vertically that you come out with less cropping on the top than on the bottom. E.g. 116 top, 150 bottom. You need to play your content and watch the heads to get an idea about that. If you shoot a non-standard aspect ratio, you only have the choice afterwards to either introduce black bars (pillar-/letter-box), or lose more or less pixels. The more your shooting aspect ratio deviates from either flat or scope, the larger the black bars, or the more pixels you lose.
If your questions intention is to crop away these black bars that you see in preview while using the original format without any cropping of active image - that is not possible. If there is not enough image to fill any dimension of a DCP container, it HAS to be filled with black to maintain the proper container dimension. Wether it displays as black bars on an actual cinema screen, it, again, depends on the screen layout and masking. What you see as black bars in DCP-o-matic preview could actually be the side walls or curtains of an auditorium, depending on screen shape and projector preset.
4096*2480 is 1.65:1, so, roughly 'the old' TV wide screen or Super 16 format (1.66:1).
Is this DCP targeted towards a specific screen (e.g. a premiere), or for a wide distribution?
When I create DCPs for our own screen, I know our screen design and I know we have side adjustable masking - so I can make the best decisions based on that specific screen, often creating non-standard aspect ratios that perfectly fit our masking. When I create a DCP for a wider release that is meant to play in a range of different cinemas, I usually create one of the two standard aspect ratios flat or scope, and, if necessary, with some letter- or pillar-boxing. Some one has to make a decision about the amount of cropping that is acceptable, and wether the cropping could be asymmetrical (e.g. more on the bottom to leave more head room).
First of all, use the latest version 2.16, as it provides better cropping and scaling options than the previous 2.14.x builds.
Flat/1.85:1 4k container is correct. You need to crop away quite a bit from the top and bottom in order to fill the flat screen without any letterboxing.
Now, without any content (active image/framing/safe frame) related concerns, I would use these parameters. But again, at roughly 130pixels crop from top and bottom, you may shift the image a bit vertically that you come out with less cropping on the top than on the bottom. E.g. 116 top, 150 bottom. You need to play your content and watch the heads to get an idea about that. If you shoot a non-standard aspect ratio, you only have the choice afterwards to either introduce black bars (pillar-/letter-box), or lose more or less pixels. The more your shooting aspect ratio deviates from either flat or scope, the larger the black bars, or the more pixels you lose.
If your questions intention is to crop away these black bars that you see in preview while using the original format without any cropping of active image - that is not possible. If there is not enough image to fill any dimension of a DCP container, it HAS to be filled with black to maintain the proper container dimension. Wether it displays as black bars on an actual cinema screen, it, again, depends on the screen layout and masking. What you see as black bars in DCP-o-matic preview could actually be the side walls or curtains of an auditorium, depending on screen shape and projector preset.
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friedmanme7
- Posts: 2
- Joined: Tue Sep 13, 2022 3:07 pm
Re: How to properly crop a 4K DCP
That reply was super helpful. Thank you!