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If a 4K cine' scanner was a camera...how many MP would it be?


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I think what’s confusing is that you often hear that for print publication you should deliver a 300 DPI image but that doesn’t mean an image that is 300 pixels wide, it means more that if printed 10” wide, it would have to be 3000 pixels wide to be 300 DPI. If I understand correctly.

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43 minutes ago, David Mullen ASC said:

I think what’s confusing is that you often hear that for print publication you should deliver a 300 DPI image but that doesn’t mean an image that is 300 pixels wide, it means more that if printed 10” wide, it would have to be 3000 pixels wide to be 300 DPI. If I understand correctly.

I know nothing about 35mm DPI but in computing, the DPI is used for printing to demonstrate how many linear dots are needed to replicate an inch of pixels on a standard display. Most computer monitors (at least historically) are about 72 DPI. Because monitors can display more colors than printers can (which are working with CMY color and black generally), the printer has to dither the image to try to replicate a similar look. Graphical content usually needs a minimum of 300 DPI to look blended properly. So you need roughly 4-6 "dots" of printing to replicate each pixel. A very strange concept it is and quite confusing.

Edited by Matthew W. Phillips
misspelling
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6 hours ago, David Mullen ASC said:

Depends on the height of the scan.  If it is a 4x3 image, then 4K x 3K would be a 12MP scan.

A 35mm frame is 24mm wide, which is just short of an inch, so does that mean almost 4000 DPI? That part I've never quite understood.

I mean the full size maximum the scanner would produce. 

DPI is dots per inch. It is adjustable on flatbed scanners. It is a measure of resolution.

Just wondering the resolution ability of a cine' scanner compared to a digital camera or flatbed scanner. 

 

Edited by Daniel D. Teoli Jr.
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7 hours ago, David Mullen ASC said:

Depends on the height of the scan.  If it is a 4x3 image, then 4K x 3K would be a 12MP scan.

A 35mm frame is 24mm wide, which is just short of an inch, so does that mean almost 4000 DPI? That part I've never quite understood.

Correct. So if you have an image with a given resolution of let's say 4000x3000 pixels, in print, where they require a 300 DPI image, you could print that image 13.3x10 inches large, before you risk seeing the pixels.

This high DPI is for glossy print magazines - a billboard which is viewed from a much larger distance can be printed with a 72 DPI image or even lower.

The viewing distance and the raster image process is the determining factor here.

Edited by David Sekanina
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2 hours ago, Daniel D. Teoli Jr. said:

I mean the full size maximum the scanner would produce. 

DPI is dots per inch. It is adjustable on flatbed scanners. It is a measure of resolution.

Just wondering the resolution ability of a cine' scanner compared to a digital camera or flatbed scanner. 

 

my Epson V850 claims to have an optical resolution of 9600 DPI. In reality it's more like 4000 DPI, so I scan at 4000 DPI.

So if I scan a 6x7 slide at 4000 DPI on it (2.3x2.7 inches) i get a 9200x10800 pixel scan from it - a 100MP image.

But a much smaller 35mm slide 36x24 (1.4x0.94 inches) only results in a 5600x3760 pixel scan - a 21MP image

That's why I bought a dedicated 35mm scanner for my 35mm film. The flatbed scanner is fine for medium format film, not so great for 35mm film.

(all numbers rounded)

Edited by David Sekanina
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7 hours ago, David Mullen ASC said:

I think what’s confusing is that you often hear that for print publication you should deliver a 300 DPI image but that doesn’t mean an image that is 300 pixels wide, it means more that if printed 10” wide, it would have to be 3000 pixels wide to be 300 DPI. If I understand correctly.

Yes. Simply specifying "300dpi," which is what's commonly specified, is completely meaningless. One could provide an early-90s computer screen grab 300 pixels across and accurately claim it's 300dpi if you print it an inch wide. It's more reasonable if you assume "300dpi at a reasonable size" but without knowing what the page layout will be, there's a lot of wiggle room in "reasonable."

Many people who work in publishing have been told to ask for "300dpi" with very little understanding of what it means. Generally my working policy is that images supplied for print should be several thousands of pixels across and that seems to work out OK.

And that's for photos. If we're doing text and graphics and we want text to look really good, especially when it will be printed on a good inkjet or commercial offset printer, 600 to 1200dpi is a better target. Magazine pages are generally output at that sort of resolution to keep the body text looking crisp.

In these days of 12-plus-megapixel digital cinema cameras outputting images 8K across and more, the resolution gap between moving, still and printed images is starting to close in any case.

P

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