Scanning old photos for Cinema Release

wayned11197107  wrote So my project is 4K 3840 x 2160...Would I literally just double the amount 7680x4320?

It depends on how good your scanner is. More specifically, its maximum hardware scanning resolution.

In principle, if your project is 4K 3840 x 2160 and you want to be able to scale up images by 200% in the timeline, then sure, ideally 7680 x 4320 is what you want. But…

A lot of scanner sensors don't go up that high. For example, suppose you have a scanner with resolution of 6000 x 4000 pixels in the hardware. And the software lets you save a file much higher than that, let's say 9000 x 6000. You will be tempted to say “Oh, it can output 9000 x 6000 so I’ll just ask it for 7680 x 4320, no problem.”

The catch is, if the hardware resolution of the scanner is 6000 x 4000, then the way the scanning software saves a file with more pixels than that is to interpolate — it will “make up” the extra pixels. This will probably only bloat the file size without adding meaningful data. If your scanner’s hardware resolution falls short of what you want, you would be better off scanning at the hardware’s max resolution and letting Premiere scale it, or if you want the absolute best enlargement to 7680 x 4320, do it in Photoshop using one of its higher-quality Image Size resampling options (or use a very high quality resizer like Topaz Gigapixel AI).

But if these photos are going to be in constant motion on the timeline (panned and zoomed), small details will get blurred anyway, in that case it’s probably not worth an extra upscaling step beyond the scanner’s maximum hardware resolution.

To summarize, I would recommend setting the scanning software to save your files at 7680 x 4320 or the scanner’s maximum hardware resolution, whichever is lower.

P.S. Of course, I never mentioned DPI (or more accurately, PPI) in this post since there was no need to. Sure, PPI will come into play when you scan, but the correct PPI will always be: Whatever scanning PPI that results in 7680 x 4320 given the different physical sizes of each original photo. For example, if a photo print is 6 inches across and you need a scan of it to be 7320 pixels wide, it needs to be scanned at 1280 ppi (7320/6). But if you need to scan a 35mm slide frame for 7320 pixels wide, that little frame is only 1.42 inches wide, so it must be scanned at 5408 ppi. If you are using well-designed scanning software, you won’t need to know all that or do any math. You should be able to just tell it the final pixel dimensions you want, without referring to inches or PPI/DPI, and well-designed scanning software should be able to do the math for the resolution it should use to scan the given original size, to achieve the 7680 x 4320 pixels that you ask for.

You are still talking dpi... Ann is talking screen size, such as 1920x1080 or 1280x720