4K UHD vs DCI

This might sound a stupid question. Please bear with me, it's out of an inexperienced person, but with so much passion towards videography.

I have footage taken in Open gate 6K. I exported 2 videos, one in 4K UHD and another one in DCI. I noticed that 4K UHD shows more of the video than 4K DCI.

left: UHD - right: DCI

Screenshot 2024-09-19 at 11.06.30 AM.jpeg (571.95 KiB) Viewed 3076 times

My default Image scaling - projects settings for all projects.

Image scaling

Screenshot 2024-09-19 at 11.14.26 AM.png (492.48 KiB) Viewed 3076 times

Scaling full frame with crop means that the image will be scaled into the frame so that everything fills cropping one of the directions. Scaling entire image to fit will scale the first direction (width or height) to hit the edge will determine the size and the other direction will be blanked.

Note the the right image (DCI) shows more of the wall on the right side. Oh, and now I see more height is the left image

Actually the DCI (on the right) is showing more. Note the blanked spaces above and below. Scaling full frame with crop means that the image will be scaled into the frame so that everything fills cropping one of the directions. Scaling entire image to fit will scale the first direction (width or height) to hit the edge will determine the size and the other direction will be blanked.

Note the the right image (DCI) shows more of the wall on the right side.

Many thanks Jeffrey.

What's the best option for scaling if I want image to be scaled from center?

You're right, DCI shows more of the right side, but the UHD have slightly more space top and bottom.

yes, I have edited my previous post.

Center crop with no scaling will put the image in the center and then crop all around.

Note also that your output scaling can differ from your input scaling

yes, I have edited my previous post.

Center crop with no scaling will put the image in the center and then crop all around.

Note also that your output scaling can differ from your input scaling

I'll try Center crop. Thank you!

Center crop is out of the equation. I'll stick to Scale full frame with crop.

I appreciate your input, Jeffrey.

yes, I have edited my previous post.

Center crop with no scaling will put the image in the center and then crop all around.

Note also that your output scaling can differ from your input scaling

How do you do center crop? Is there an option?

It’s one of the scaling options in the DaVinci Resolve / Project Settings.

It’s one of the scaling options in the DaVinci Resolve / Project Settings.

Thanks. I was looking in the inspector.

I did a quick comparison between Open gate, 6K DCI and 6K 2.4:1. Exporting open gate in 4K UHD timeline shows more of the footage. However, the latter ones exported in 4K DCI timeline shows more.

It should be noted though that DCI is not really meant as a delivery format but as a capture and post "canvas" that you can then extract your delivery formats from with an optimized vertical or horizontal resolution.

So if you capture or post in 4K DCI, you can extract either a UHD or a 1.85 that have a vertical resolution of 2160P at different widths. And if you deliver at 2:1 or 2.39, you have some extra width to work with at a reduced height.

When working with a full frame cam original, you'd usually want to optimize for the width of your delivery format, whether it's UHD, 1.85, or 2.39 and let the height fall where it may.

There is really no reason to export a DCI size file -- unless of course one is creatively attached to the esoteric feel of a 1.89629:1 aspect ratio, which I'm sure will be a thing for some people.

It should be noted though that DCI is not really meant as a delivery format but as a capture and post "canvas" that you can then extract your delivery formats from with an optimized vertical or horizontal resolution.

So if you capture or post in 4K DCI, you can extract either a UHD or a 1.85 that have a vertical resolution of 2160P at different widths. And if you deliver at 2:1 or 2.39, you have some extra width to work with at a reduced height.

When working with a full frame cam original, you'd usually want to optimize for the width of your delivery format, whether it's UHD, 1.85, or 2.39 and let the height fall where it may.

There is really no reason to export a DCI size file -- unless of course one is creatively attached to the esoteric feel of a 1.89629:1 aspect ratio, which I'm sure will be a thing for some people.

Tamas, thank you for your input. In most of my previous videos, I used 6K 2.4:1 and then used 4K DCI timeline, rendered and uploaded to YouTube. It is the first time I use 4K UHD timeline and Open Gate footage, because I know that 4K DCI is a bigger resolution than 4K UHD. For my video, I need each and every pixel possible to showcase interiors as much as possible. The reason I shoot 2.4:1 because I go up to 60fps unlike other higher resolutions.

My experience is shallow when it comes to technical details related to resolution differences and the most suitable one for YouTube.

Movie theatre screens come in two aspect ratios: Flat (1.85) or Scope (2.39). The DCI Full resolution (4096 x 2160 for 4K) is simply used by cameras to capture the minimum number of pixels that can crop down to these two aspect ratios without scaling. 4K Flat would be 3996 x 2160, and 4K Scope would be 4096 x 1716; see how DCI Full uses the higher number from each dimension?

As Tamas notes, it's not a delivery format and its purpose is largely defeated if you don't intend to deliver in one of those two aspect ratios, for a movie theatre screen. For YouTube, it's best sticking with UHD as that content will be viewed exclusively on 16:9 screens, and any content that is not of that aspect ratio will be letterboxed/pillarboxed.

Movie theatre screens come in two aspect ratios: Flat (1.85) or Scope (2.39). The DCI Full resolution (4096 x 2160 for 4K) is simply used by cameras to capture the minimum number of pixels that can crop down to these two aspect ratios without scaling. 4K Flat would be 3996 x 2160, and 4K Scope would be 4096 x 1716; see how DCI Full uses the higher number from each dimension?

As Tamas notes, it's not a delivery format and its purpose is largely defeated if you don't intend to deliver in one of those two aspect ratios, for a movie theatre screen. For YouTube, it's best sticking with UHD as that content will be viewed exclusively on 16:9 screens, and any content that is not of that aspect ratio will be letterboxed/pillarboxed.

Thank you for the explanation. Now it’s clear.