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Old 29-03-2013, 03:48 PM
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OzEclipse (Joe Cali)
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Join Date: Jun 2012
Location: '34 South' Young Hilltops LGA, Australia
Posts: 1,481
Quote:
Originally Posted by mithrandir View Post
You didn't say what values you used for "n" and "p".

Joe said he'd used n=12 and p=5.4

With 24 Mpx and p=3.89 I'm more tempted to use n=20.

Raymo didn't use my formula to generate the table. I think it's a table based on the old 35mm film rules that my formula is attempting to update. These old formulae are based on assumptions about producing prints of a certain size from 35mm film.

Mine allows you to optimize to a specific output size.

To work out n for my formula look at any image before you take the pictures. size a full size image to the screen size you want and look at the scaling percentage you want to use for display. 100 ÷ scale% x 1.5 will give you a decent value for n.

You can also do it from pixel dimensions.
Example Andrew has a 24MPx camera and wants to display a 1000x1500 image

Sensor has 4000 x 6000 pixels
Display image 1000 x 1500

Scale factor = 4000/1000 = 4
n = scale factor x 1.5 = 6

But if

Sensor has 4000 x 6000 pixels
Display image 400 x 600 pixels
Scale factor 10
n=10 x 1.5 = 15

Joe
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