Want to understand mega-pixel (mp) and the picture print out size

[harmony]

Hi,

What is the relation between Digital Camera mega-pixel (mp) and the picture print out size? I mean higher mp would translate to higher print quality.

However, I would like to know a good 3R size print what is the minimum required mp...how about 4R, 8R...and so forth. Because if for example a person would normally print 4R size photo, would he/she need a xx-megapixel camera.

Thanks...


Regards.

 

[Bean]

This depends on what ppi (pixels per inch) you want to print at. For our eyes and many printers, the upper limit is around 300 ppi. Even 150 ppi is still considered acceptable to most people. But any thing above 300 ppi is not noticable or not printable.

For example, 4R which is 4" by 6". Multiple by the 300ppi^2, you will only require 2.1MP (=4 * 300 * 6 * 300). Of course if you find 150ppi is acceptable, you would only need 0.54MP!

The above example is just a rough gauge since different photo sizes have different size ratio to begin with and you might like to take into account the cropping off areas as well when you print.

Another factor to consider besides the different size ratio is whether would you crop the image. If you like to crop your images before printing, to achieve the same ppi, you would need much more resolution.

Hgher resolution allows you to print bigger photos, provided that everything else being equal. But one thing I would like to highlight is that resolution of a camera ALONE does not translate to print quality. There are other factors that contribute to print quality like noise, lens, DSP, jpeg etc...

 

[harmony]

Thank you Bean