The MegaPixel Printing Dilemma

[frontslash]

A pixel is the smallest item of information in an image, a megapixel (MP) is 1 million pixel.

A camera with an array of 2048x1536 (2048x1536 = 3,145,728) is called a "3.1 megapixels"
In the same way the 8,10 MegaPixel cameras' have the following resolution.
8 MegaPixel Camera 3264 x 2448 = 7,997,616 "8 MegaPixel"
10 MegaPixel Camera 3648 x 2736 = 9,980,928 "10 MegaPixel"
It is worth noting that the Camera pixels are at 4:3 ratio.


Now commonly used printing paper comes at the following sizes:
Photo paper 15 x 10 cm or 5.9 x 3.9 inch
A4 standard paper 29.7 x 21 cm or 11.7 x 8.3 inch
A3 standard paper 42 x 29.7 cm or 16.5 x 11.7 inch


And printers print a differet reoluions or DPI (Dot Per Inch). A favorable printing resolutions is 300 DPI (Dot Per Inch).


So how mouch camera resolution is needed for a good print of Photosize, A4 or A3 size?

Here is a way of doing it.

We take a 8 MegaPixel Camera
Camera resolution: 3264 x 2448 = 7,997,616 "8 MegaPixel" 4:3

Now we want the printing resolution to be 300 DPI, dividing pixels by 300 we get
3264 x 2448 / 300 = 10.88 x 8.16 inch == (Averaged) ==> 10 x 8 inch or 25.4 cm x 20.3 cm

So a 8 MegaPixel camera will do a great Photo size print, but will not make a A4 full size print.



What about a 10 MegaPixel Camera
Camera resolution: 3648 x 2736 = 9,980,928 "10 MegaPixel" 4:3

The printing resolution would be at 300 DPI, dividing pixels by 300 we get
3648 x 2736 / 300 = 12.16 x 9.12 inch == (Averaged) ==> 12 x 9 inch or 30 cm x 22cm

So a 10 MegaPixel camera will do a great A4 size print at 300 DPI but will not make a full A3 size print.


Hope it helps


Ref:
http://en.wikipedia.org/wiki/Pixel
http://en.wikipedia.org/wiki/Image_resolution
http://www.photo.epson.co.uk/creativ.../print_big.htm
http://www.design215.com/toolbox/megapixels.php

[Asmaa]

It is very useful and helpful information

Thanks

[frontslash]

Your welcome

[Saif Al Muraikhi]

Thanks

[Zaradashte]

Frontslash.. so this is about ratio of the image set on the ratio of the print? your not talking about the stringth of the resalotion of the picture, are you?

is very helpful indeed
Thank you

[frontslash]

Image resolution (Pixel count) has no relation with DPI until printing.

When the image is printed the DPI will decide (or tell the printer) how big the print size should be.

[Zaradashte]

Yes your right.. the dpi just like the Persian rug case, the quality of the rug measures about how many stitches are there per square inch.