how hard should it be...

[acroyear]

...to get a simple answer to the following question:

What is the optimal resolution an image file should have to not look like absolute crap when enlarged to 5x7, 8x10, 8x12, a 12x36 banner, or a 12x24 poster?

My google-fu is failing me on this.

I keep seeing things either useless, or in "DPI" - I don't think "DPI", dammit, I'm looking at 3456x2304 and 3280x2460 and I want a straight answer dammit.  DPI is all about the printer - I don't care about the printer, I am asking about the source image itself.

(I also keep seeing sites about 5mp and "expensive memory", and all that is SO 3 years ago...).

Ok, one site is finally hinting that 7200x4800 (or 34mp) is best for that 24x12 poster, so that's out with what I've got... guess I'll go with a set of 8x12s mounted side by side.

of course, along the way I run into sites about resolutions to enlarging the european parliament, and high resolution images on other...enlargements...

oh well.  gotta go for now.

Comments

[tyrus.livejournal.com]

Maybe it doesn't have a simple answer? :p

I've printed out perfectly good enlargements up to, I think, 20 or 24 inches on the long side from my 6mp 10D. That's 3072x2048 without cropping. And I know 11x14's look fine, as I just took a look at one And it depends a lot on the camera, I've seen lower MP cameras with a better sensor and better glass make better prints.

As a general rule I go by 300 pixels per inch, but my example above obviously ignores that. Do you have a Costco membership? Their enlargements are relatively cheap, I think you can get a 20x30 for $10. I'd recommend just picking an image and getting one and see how it looks.

[theshaggyfreak.livejournal.com]

Generally, if I'm doing something for print, I make sure an image is 300dpi if possible.

At 300dpi:

5x7= 1500pixels x 2100pixels
8x10= 2500pixels x 3000pixels

etc.

[wildwose.livejournal.com]

Yep, DPI does matter. Essentially, since we do this all the time with the magazine and advertising graphics etc. Hi Res, Hi MP (7 MP is really about as big as you need, but the new cameras are bigger) and 300 DPI for print.

[acroyear70.livejournal.com]

If/when I'm doing the printing, I understand DPI as important (and usually go 300 or even 600). I assume the pros will simply go for 300 and that's that.

I'm talking about professional enlargements (I only have a 3x5 printer here at home) for making wall mountings for my office. I have frames so I'm looking at the collection and picking stuff to put in them.

Some of the stuff is old enough to have come from film directly to cd, from film via crappy scanner, from film via decent scanner (but still only scanned in the 1mp range), from the canon sure-shot, and then most recently from our good cameras (my 8.1 kodak, cyd's 10+ rebel xti).

i'm talking about not wanting to send a 1mp scan to a 12x24 enlargement that will look fuzzy and blurry and pointless and a waste of $10. so what should i have in image size to look good blown up that big. in the days of 35mm film, it was a non-issue. in the digital world, it's a huge issue.

[wildwose.livejournal.com]

Sorry, Joe, didn't understand the problem, fingers ran before brain.

[blueeowyn.livejournal.com]

Take one of the files, throw it into Photoshop or equivalent and adjust the image size, find something in the file that fits on your screen and stand back and see how it looks. This won't be perfect but it might help you.

[kowari.livejournal.com]

DPI matters, in the sense that you want to be removing information not stretching it when you print out the image.
But your rule of thumb is... the more megapixels, the better the print image will be.

The optimum is the biggest you can find.

MOAR PIXELS! MEGA MEGA PIXELS. (seriously, it is. Like wildrose said, at least 7, but the higher the resolution the better)

Soooo
8x10@300DPI is 2500x3000 is a 7,500,000 image. 7.5mega pixels.

:)

[javasaurus.livejournal.com]

My understanding is that 300 dpi is good if your holding it (like a photograph or 8x10) but you can decrease that by a bit (to 150 dpi) for large printing, since it's viewed from a distance.

That means a 10 MP should be fine for up to 18 x 24 inches.

I'll see if I can find references...

[javasaurus.livejournal.com]

Here is a very nice site with information on sharpening and interpolating enlarged images. It includes a handy resolution calculator near the bottom of the page -- enter the viewing distance and some other parameters, and it spits out your needed dpi.

[skivee.livejournal.com]

Javasarus is wise in his words. If you were viewing the banner at the same distance as the 8x10, then you would need a gagillian
mega-deca-pixals
If not, the increased resolution becomes less important proportionally as size is increased.

[acroyear70.livejournal.com]

well, yes it is meant for a wall poster (i already have the frame) so i'm gonna skip that idea and just go with multiple 8x12s with a little space between them.

yep dpi matters

[kitteblue.livejournal.com]

But a good rule of thumb is 300 dpi, that's the current standard for most shops.