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Upscaling: pixels vs dpi

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Hoping for some guidance - recently offered images for printing at 300dpi but the images needed to be physically bigger when printed - 150% bigger in fact, so I increased the pixels, forgot to turn off resampling (smoother) and used sharpening tools to try to maintain sharpness. 

The question: I was debating whether to work at 240 dpi as standard in future instead and increase the pixels to match the size requirements.

Or due to the lower dpi should I be working at a higher pixel size than required to compensate for the increase to 300dpi later on?

Technically, these aren't photos but cartography (maps for D&D) which will likely cover a table after being rolled out. But still would appreciate any help, thank you!

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Hi Damien, they're graphics created in photoshop at 300dpi - it's a comgination of these assets with transparent backgrounds over layers with textured patterns to simulate terrain. Stylistically its less realism and more comic in style - they require oversize printing though, since the smallest one is 14 inches in physical length



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This is such a complex issue, but it boils down to this:  No matter what the size or pixel dimensions or resolution, the print will only ever be as good as the poorest-quality element of it.  And I can see from what you provided that the quality of some of the elements is pretty poor.

This would have been an issue no matter whether you began with a 72, 240, 300, 600, 1000 or 3000 ppi file.  The smallest, crappiest graphic in your collection is still the smallest and crappiest, no matter what.  On screen, and in print (at any size) it will still be crappy.  Am I making sense so far?

Now, we could make this argument:  Make the file at the same low resolution as the smallest crappiest element.  Shrink all the other elements down to match it.  Then, when you come to print, enlarge it all really aggressively.  It'll all look terrible, but at least it will all be exactly the same amount of terrible.  It'll be perfectly consistent.

Or, you could do what you appear to have done - made a high resolution file, allowing the best elements to look their best, and the small crappy elements to continue to look small and crappy.  This approach means everything is wildly inconsistent, but at least some parts of the image are sharp.  Am I still making sense so far?

I have another question for you - did you know, before you started making this, what size it would be needed to be printed?

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For this map? Nope, my old system couldn't handle the 1inch grid at 300dpi so I planned to just have it print out at smaller sizes instead (figured most ppl were going to use it for online table top). For online use at 72dpi, the varying quality isn't as obvious, thank god.

People who bought it for print tho, started blowing it up at 200dpi. It turns out, they really want their 1inch grids for play with token miniatures at their local gaming store. The good thing is that once printed, people will be looking at it from across a table so the edges won't be as obvious (hopefully).

The graphic assets were purchased for commercial use from a third party cartographer. Now, if I were drawing the elements from scratch, I'd have them as vector art to maintain consistency, but this is more a hobby and to give back to the community. They don't have color maps for RPG adventures besides black and white marker drawings and this would allow for better immersion during the game. The only way to make any real money off it would be to get hired by the publishers, which is not happening.


Edited by Gaild
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There's only one grid, depending on the physical size of the picture, the grid is 1inch - or smaller. At biggest currently this particular map is 16.5 inch high and 26 inches wide in print

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So, for future reference (for these maps), here's a rough guide:

  • For anything under 12 inches (12 grid squares) wide, use 300ppi.
  • For 12-16 inches, use 250ppi
  • For 16-20 inches, use 200ppi
  • For 20-30 inches, use 150ppi
  • For anything larger than 30 inches, use 100ppi

(Please note, this does not apply to photography - I'm only providing it for these maps.)

Make sense?

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You probably already know this, but just to make sure - never copy and paste the design elements into your layout.  Only File>Place, or drag and drop from Bridge.  This ensures they come in as Smart Objects.  Smart Objects can be resized and rotated as many times as you like, and they never lose their original quality.  This is vital for this kind of work.

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