# MP question...

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#### agape01

##### Senior Member
Out of curiousity, how many MP would I need to print 2.1m by 3.15m print?

Just a wondering thought.

Thanks

#### poh6702

##### New Member
Hi

Just throw in my idea although I am not experience in this area.

In general 72DPI (Dot per inche) is good enough for general quality. A 15" LCD monitor with 1024x768 is having about 85 DPI and if you are happy with the display, that is good enough.

If I based on the calculation, 3m x 2m will requires 8845 x 5896 pixels to have resonable quality at close up view, this translate into 52Mega pixels. But then who will view such a big posters at 1 foot distance?

If you are hanging the poster on top of 10 storey building along highway to catch attention of drivers, then 2 mega pixels is sufficient.

A projector with 1024x768 resolution is good enough to project picture up to 2m x 1.5m on the screen for viewer sitting at 10 feets away.

The answer depends on your contents and how is it going to be viewed.

#### megaweb

##### Moderator
Staff member
1" = 2.54 cm
1cm = 1/2.54" = 0.394"
1m = 39.4"

To convert metres to inches,
2.1m by 3.15m = 39.4"(2.1m by 3.15m) = 82.74" x 124.11"

for 300 dpi print, you need resolution of 300 (82.74" x 124.11") = 24822 x 37233 which is 924 megapixel

for 150 dpi print, you need resolution of 150 (82.74" x 124.11") = 12411 x 18616.5 which is 231 megapixel

for 72 dpi print, you need resolution of 72 (82.74" x 124.11") = 5957.28 x 8935.92 which is 53 megapixel

#### szekiat

##### Senior Member
and in a real life scenario we'd all use a 4mp camera and get away with it...

#### agape01

##### Senior Member
Thanks for all of your replies...

They are greatly appreciated.

So at 8mp or 12mp, that would be sufficient enough?

#### benny

##### Senior Member
Perhaps you can consider shooting on film (medium or large format) and drum scan in high resolution?

Cheers,

#### mpenza

##### Senior Member
depends a lot on how the print would be viewed too. if it's going to be scrutinised up close, you'll need higher resolution.

#### jj1987

##### New Member
Get someone to shoot a 4x5 positive, then have that drum scanned. Expencive? yes, but it gives you decent quality. Now, something to remember is most billboards are UNDER 100 Megabytes saved as TIFF, so just remember viewing distance.

best thing is to save your file and

Image-->Image Size, set to how you want it
View--> Print size and thats how the print will look.

Thats what you need to do in photoshop to see how anything will look.

#### agape01

##### Senior Member
Thanks so much for all comments listed.

They are all greatly appreciated.

#### yanyewkay

##### Senior Member
agree with mpenza, these large sized prints are normally hung for viewing from a distance.

#### Sputnik

##### New Member
For a user of a D2X ... you probably have more than enuf mega pixel to print files to anysize ... (Goodyear blimp included) ...

and for such purposes ... nobody uses 300dpi to print it ... the resolution is much lower .. even to 2 digit figures...

you should know better since you have been in this business for quite a long time ... especially for covering international conferences ....

which advertising campaign are you working on?

do share with us your impressive works

Happy Shooting

#### canturn

##### Senior Member
A 6MP TIFF from medium format back can print larger than that size after interpolation.

It's not just a question of file size, it's how much detail can your sensor pick up.

I've printed 20x30" quitely comfortably with a 4MP file from the canon 1D, after interpolation and sharpening. 8MP from a DSLR should be able to print quite decently on a printer with RIP

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