In which @slhck explains & compares DPI & MegaPixel

Conversation started Jan 4, 2013 at 10:49.

Einsteins Grandson

Jan 4, 2013 10:49

When somebody asks me to make pictures by camera that are gonna be 400-600 DPI..... what megapixel ( resolution ) shout the photos I make be?

Or DPI and megapixel/resoulion of photo are 2 different properties?

slhck

The answer is: It doesn't matter.

HackToHell

@slhck no more free will !

@EinsteinsGrandson because everything is an illusion

slhck

@EinsteinsGrandson You can set a 300 megapixel photo to 600 DPI and you can set a 1 Megapixel photo to 600 DPI. It doesn't matter.

The real question is: What print size should the photo have?

Einsteins Grandson

I should make a paper in MS Word.... so the size will be small

slhck

Go the other way when calculating: You want, let's say an image with 3x3 in.

Einsteins Grandson

Jan 4, 2013 10:53

ok , then?

slhck

When you print something you want to print at least with 300 DPI. Better 600 DPI.

That's how many pixels are actually put in a square inch

So if you want to print 3x3 in with 300 DPI you need a 900x900px photo

And if you want to print at 600 DPI you need a 1800x1800px photo

But this all depends on what the print size should be (in that case 3x3 inch)

See what I mean? :)

Einsteins Grandson

Yest

slhck

So you first need to know how big the result should be on paper.

Einsteins Grandson

Yes

Just imagine each picture will be square

slhck

Okay. How big are they going to be on the paper? 5x5cm, 2x2in?

Einsteins Grandson

Jan 4, 2013 10:56

and the maximum lenght of one side will be 16cm

which is 6.3 inches

slhck

Okay. So 16cm is 6.3in. 6.3 * 600 is 3780px.

That means your original photo has to be at least 3780x3780px for perfect print quality.

Einsteins Grandson

and when I only need 400 DPI ?

slhck

6.3 * 400 = 2520px

Einsteins Grandson

6.3 * 400 =

slhck

exactly :)

Einsteins Grandson

Jan 4, 2013 10:58

2520 x 2520 is how many megapixels?

slhck

Roughly 6

Einsteins Grandson

6.3 megapixel ?

do you have a link to the website?

i.sstatic.net/NaKwI.png ?

slhck

What website?

@EinsteinsGrandson That's Photoshop, actually

Einsteins Grandson

;o))))

I see

slhck

But I guess any half way decent image editor should do that

IrfanView probably has that as well, for Windows. Or Paint.NET

Look at this article: DPI and YOU - Understanding Resolution for Print and Web - Beginner Tutorials - Paint.NET Forum

Conversation ended Jan 4, 2013 at 11:00.

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In which @slhck explains & compares DPI & MegaPixel

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