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It should be 300dpi. If you are going to print it in greyscale, it's best to create it in greyscale. This will force you to be careful about using values to differentiate different areas rather than colours.
Qualities Of Maps For Printing
For the last while I've been playing with maps that generally speaking are either going to be displayed on a computer screen or printed on a full color laser printer.
Needless to say, they don't look so hot if you have to print them on a black and white printer that's capable of greyscale. What sort of qualities does a map need to have if it's going to be printed like this?
I guess my question is really, if I'm drawing a map with the intention of including it in a product that someone else might want to print, what should it look like?
It should be 300dpi. If you are going to print it in greyscale, it's best to create it in greyscale. This will force you to be careful about using values to differentiate different areas rather than colours.
I was told (at my local copies store) that 240dpi was perfect for color prints. Any higher than that and the dots don't align properly and it can start splotching and running together on the prints. That was for Color tho. Grayscale could be different.
It's always possible that the person didn't have a clue what they were talking about either ;-)
The most correct answer, of course, is that it depends on the desired output size/viewing distance, the device you're printing to, the media used. Dye sublimation machines have different needs than laser printers which are different still from inkjet printers. Glossy media tends to hold a greater number of dots per inch without blurring than rougher media such as paper.
A good rule of thumb is that most people will tend to not be able to resolve the individual dots at 18" somewhere around 250 dpi. A poster can often be lower resolution because it will be viewed at a greater distance. Some examples: a fax on low resolution is 100dpix200dpi, a fax on fine resolution is 200 dpi in each direction, an old laser printer is around 300 dpi, a modern inkjet or laser printer is 1200 to 2400 dpi, and a screen image is typically 72dpi or 96dpi.
Something important to note is that most print shops have approprite software and hardware to scale your image correctly to the hardware. However, if you start out with too low a resolution they can only do so much to make it look good on their machine.
My recommendation is that you get familiar with the capabilities of the medium to which you'll be outputting your images and then try to match the data to the device and situation. Not overly helpful, I know, but experimentation is the key to best results.
Last edited by waldronate; 03-27-2009 at 06:47 PM.
I wrote quite a bit about all this sort of stuff here:
http://www.cartographersguild.com/showthread.php?t=2596
Well I guess if there is some alignment going on then it probably means that the printshop will halftone your image at 240dpi and print it no matter what dpi you give it. As said in the tut above, you should let the printer do the halftoning and not try to do it yourself. So give the printshop a continuous greyscale image not a dithered black and white one with any particular halftone or error diffusion dither on it.Originally Posted by Wag
If you do give them one dithered near to but not exactly 240dpi and then the printshop prints it with a 240dpi screen or something similar then it would look terrible. You would get the effect that you see in my tut with the zebra stripes.
Cool. Thanks for the info. What about the design side? What sort of stylistic concerns should I be mindful of? I know that I shouldn't use too much black and that I need to make sure my maps are readable. What else?
If you're printing in color, you should probably use some kind of color reference to be sure you get the colors you want. I use a little book called The Color Index, which has hundreds of different color schemes sorted by mood, and it gives the CMYK and RGB values for each color in the scheme.
The colors on your monitor will never match the print, so you can't rely on your screen to tell you what the map will look like. I learned that the hard way with one of my projects this term. What I thought was going to be blue turned out to be violet. That little mistake seriously weakened what was supposed to be a patriotic poster. Red, white, and purple just don't quite communicate the right message.
Bryan Ray, visual effects artist
http://www.bryanray.name
All I can add is...put a light stroke or outer glow around text so that any underlying black or dark gray doesn't run into the text. If you have a color image and want to print it in grayscale, things like red and brown and blue tend to blend together so it's easiest to just make it grayscale in the first place as previously stated...otherwise you have a lot of editing/repainting to do.
If the radiance of a thousand suns was to burst at once into the sky, that would be like the splendor of the Mighty One...I am become Death, the Shatterer of worlds.
-J. Robert Oppenheimer (father of the atom bomb) alluding to The Bhagavad Gita (Chapter 11, Verse 32)
My Maps ~ My Brushes ~ My Tutorials ~ My Challenge Maps
Make sure that you consistently check the map at print resolution (in gimp you do this by switching off view->View dot for dot). Make a decision about the text size and style on each map and stick to it for all of them. If it's a greyscale map then make sure that you keep an eye on the spread of values by checking the levels. It's very easy to have all the details of an image clustered around mid-grey - especially if you are used to colour work. Ideally you want a good spread throughout the range of values.
Make sure that the important things remain clear - in a map this will be things like the border between floors and walls, roads, coastlines and mountain ranges on regional and world maps, different houses and their labels in a town map. It's easy to get lost in detailing different elements and then not notice that they no longer stand out as different distinct elements at the print scale.
If it's for the clients customers to print themselves, say for a pdf, then check whether they want a printer friendly version. For this you want to keep your lines dark to delineate the different elements, but then pull all the other values right up to the high end - nearly white - so as to save the customer on ink.
If your maps might be used for VTTs then make sure you place the map on one set of layers, any grid on another, any objects (tables, doors - literally anything not nailed down) on another and labels on another. Some publishers will want versions with/without any of these individual sets of elements. Also remember that if it's for pdf printing, they are likely to want a version without DM information on it (secret doors and traps for example).
Finally, remember to sign it, and if it's a jpg then fill in the jpg information (on Gimp this is under the advanced options in the save as jpg dialogue) to include your name, the product it was created for and the copyright information.
That's all I can think of off the top of my head.
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