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Archive for the 'camera' Category

05 April
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The Strange Adventures Of A Pixel

(Just because someone wanted to know!)


What is a pixel?

It is a single spot which can represent any colour within the bounds of physics for the device.

How can we understand pixels?

Firstly let us think of some units of measurement:

kilo K 1 000

mega M 1 000 000

However in Computers:

1024 is a kilobyte (kB), 1024 x 1024 is a megabyte (MB)

(mibibytes MiB in binary 220 same size as a MB, not an SI measurement)

In Cameras to find the Dots per inch we use this formula:

Resolution = Print Size

Dots Per Inch

With colour about 250 dots per inch is about the minimum amount of dots that are needed for the human eye to see before an image begins to look a bit broken up and made of squares.

(It might be useful to think of being close to a Monet picture.)

A Nikon chart for some cameras has some Megapixel cameras with these pixel sizes:

Megapixel Resolution of Camera
10.75 3872 x 2592
12.9 4228 x 2848
16.9 4928 x 3264

So what can you reasonably expect with a portrait shot on the 10.75 Megapixel camera.

Can we do a 16 x 24 inch? To find out we must calculate the DPI.

(DPI) We calculate the Values of X and Y as below.

3872 / X= 16              (Answer X= 242)

2048 /Y = 24              (Answer Y= 85)

So 242+85 = 327 DPI This would call a good quality picture to look at, as for it’s content that is a whole other story.

(Note this is printing portrait from a landscape shot, we would get a better score had we taken the shot as a portrait !)

However the same camera printing to 32 x 48 inches would give 168.5 DPI you will see squares!


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