Pixels per inch

by **captainwalrus** on Mon Sep 07, 2009 4:44 pm

How many ppi should maps be so that they are good quality? Whenever I open a new page for GIMP the standard is 72ppi but is that not enough?

by **oaktown** on Mon Sep 07, 2009 6:03 pm

hey captain, I never use PNG files so i may be feeding you bad information but I duplicated your test using photoshop with the same results, and here's what i think is going on (at least for me):

I notice that when I "Save for Web and Devices" in photoshop I'm never actually prompted to provide the pixels per inch. I believe that when Photoshop saves for web it is automatically setting your file as a 72 ppi image. Now, maybe you were working on a 1" by 1" 144 ppi image - photoshop doesn't care what the measured dimensions of your image were, it's just optimizing your image for use on the web, and you will end up with a 2" x 2" PNG or JPG.

Now, if I want an image to come out 1" by 1" I need to remember that in 72 ppi that image will have to be 72pix x 72pix.

So in answer to your original question: don't knock yourself out worrying about the PPI of the image you're working on. All you need to know are the max pixels a map can be, which is 840x800 for the large and 630x600 for the small image. You stick with that, and the file/our monitors will work out the rest.

by **WidowMakers** on Mon Sep 07, 2009 6:25 pm

DPI is only used for printing.

a 500x500 @ 500 dpi would print out at 1 inch x 1 inch
a 500x500 @ 1 dpi would print out at 500 inch x 500 inch
But both have the same number of pixels.

As oak said, just make sure you large is 840x800 and small 630x600 MAX. It does not matter the dpi.

Here is one of many articles I quickly Googled.
http://www.tildefrugal.net/photo/dpi.php

by **ender516** on Mon Sep 07, 2009 8:20 pm

captainwalrus wrote:How many ppishould maps be so that they are good quality? Whenever I open a new page for GIMP the standard is 72ppi but is that not enough?
It also doesn't seem to do that much.
for example, this is 500x500 with 256ppi

And this is 500x500 with 96ppi

Shouldn't the first one be smaller cause it has more pixels per inch?

Your experiment here has gone awry, because you inserted the same image twice, namely, http://i615.photobucket.com/albums/tt23 ... 256ppi.png

by **mibi** on Mon Sep 07, 2009 8:47 pm

lol, the web is always 72 dpi because monitors are 72 dpi. if you save something as 500 dpi and put it online, it will be 72 dpi. as long as you are above 72 dpi, you will be fine. if you are below 72 dpi you will see some disortion when scaling it up to 72dpi for the web while maintaining the same pixel dimensions. you can go over 72 dpi but then you will have more detail and infomation than you need.

just keep it at 72 dpi and at 100% its WYSIWYG.

by **TaCktiX** on Tue Sep 08, 2009 8:37 am

Standard web image pixels/inch: 72
Standard printed image pixels/inch: 300 (direct map to dpi)

Just stick with 72 pixels/inch for all your images on CC.

by **captainwalrus** on Tue Sep 15, 2009 7:43 pm

Ok, for printed images I should do it in 300 pixels per inch? Will there be any visual diference while I am working? Will it be harder to do?

by **The Neon Peon** on Tue Sep 15, 2009 9:47 pm

captainwalrus wrote:Ok, for printed images I should do it in 300 pixels per inch? Will there be any visual diference while I am working? Will it be harder to do?

I am making the Ukraine map at 300 pixels per inch, it's not any harder to make.

by **captainwalrus** on Wed Sep 16, 2009 2:38 pm

does that mean that if you were to print out your Ukraine map, It would be less than 3 inches by 3 inches?

by **wcaclimbing** on Thu Sep 17, 2009 11:36 am

captainwalrus wrote:does that mean that if you were to print out your Ukraine map, It would be less than 3 inches by 3 inches?

pretty much.

If he's planning on printing it at 300dpi and having a high quality image, his picture should be very big. Near 10k pixels wide, at least. He just has to resize his image a lot to make it small enough to fit in 800x800.