DPI vs. PPI - What's the difference?

[RPMiller]

You are over complicating it. As I explained in the reply to your PM, we don't care what the dpi is. We aren't printing it. What is a dot on the screen, how does that compare to a dot on a printer? Just keep it simple.

[Midgardsormr]

Heh. I think the answer to the question is "yes." DPI may not matter to you, but I suspect it might to Gamerprinter!

[RPMiller]

Not in this instance. He is talking to me specifically about VTTs. There is no need to print when you are playing directly on the screen, but I get the irony of the statement and his name.

[Gamerprinter]

A digital image is measured in pixels. When a pixel is printed, it is represented by a dot. Therefore dpi and ppi is the same thing - one in its digital format only (pixels), the other in print (dots).

All graphics are measured interchangeably as dpi or ppi - I've got software that refers to both.

A 200 dpi or ppi image is measured as 200 x 200 dots or pixels. Most software I use only refer to dpi, even when an image is never intended to be printed.

So the issue is semantics. Unless you've got some other specific way to describe 200 pixels = 5 feet, there's only one way for me to make it.

So I do believe I am correct. I am not making it more complicated. The software I refer to mentioning ppi was Micrografx Picture Publisher and it nolonger exists. All other graphics software refer to dpi interchangeably with pixels.

Its a simple question.

[Robbie]

Nice work GP...I'm also quite thoroughly impressed with the exterior map...The interior map shows a LOT of work done, but for my own tastes it may be a wee bit too texture heavy...I'm not saying thats a bad thing, as I'm more of a minimalist in my approach to mapping...I definitely agree that these would go really well with VTT.

As for the dpi/ppi/200 argument...there is no argument really...200 pixels per 5 square feet = 200 dpi scaled print for D&D size miniatures = good for everyone

[RPMiller]

A digital image is measured in pixels. When a pixel is printed, it is represented by a dot. Therefore dpi and ppi is the same thing - one in its digital format only (pixels), the other in print (dots).

All graphics are measured interchangeably as dpi or ppi - I've got software that refers to both.

A 200 dpi or ppi image is measured as 200 x 200 dots or pixels. Most software I use only refer to dpi, even when an image is never intended to be printed.

So the issue is semantics. Unless you've got some other specific way to describe 200 pixels = 5 feet, there's only one way for me to make it.

So I do believe I am correct. I am not making it more complicated. The software I refer to mentioning ppi was Micrografx Picture Publisher and it nolonger exists. All other graphics software refer to dpi interchangeably with pixels.

Its a simple question.

Nice work GP...I'm also quite thoroughly impressed with the exterior map...The interior map shows a LOT of work done, but for my own tastes it may be a wee bit too texture heavy...I'm not saying thats a bad thing, as I'm more of a minimalist in my approach to mapping...I definitely agree that these would go really well with VTT.

As for the dpi/ppi/200 argument...there is no argument really...200 pixels per 5 square feet = 200 dpi scaled print for D&D size miniatures = good for everyone

While I understand and appreciate and agree to some extent with your assessment of dpi, it is not entirely accurate. As I've mentioned I have a background in reprographics from 15 odd years ago as well as some formal training in the area of computer graphics. This dpi/ppi argument has been around a long time and unfortunately those that don't fully understand it are in the majority and even the application designers get it wrong sometimes because of the way the older software worked and used the terms.

Here is just one of many links that you can find on the subject, but I picked this one specifically because it has print shop links as well. Please understand that I'm not trying to be a jerk about this, and I agree that we are essentially saying the same thing, and in this instance it isn't important as the software obviously is doing it correctly, but we really should be using the correct terms and it is always good to learn something new. I've talked to many reprographics folks over the years and many of them get this wrong because they are usually self taught or don't have the diverse background that would have introduced them to the differences in the terms. Not to mention, as I stated, the software itself is misleading.

http://www.rideau-info.com/photos/mythdpi.html

I would encourage everyone to investigate this further, and if we want to discuss it some more, since it definitely falls into the realm of this site, I think starting a new thread would be a great idea.

[ravells]

Might be worth moving the relevant posts from here to a new thread too for when people come to look at the threads come judgement day

Ravs

[Carnifex]

Here is just one of many links that you can find on the subject, but I picked this one specifically because it has print shop links as well. [U]Please understand... (CUT) ...misleading.

http://www.rideau-info.com/photos/mythdpi.html

I really must say that while the most information on the linked page is correct he doesn't get it all correct.

Here's some links to Wikipedia that's relevant:
http://en.wikipedia.org/wiki/Dots_per_inch
http://en.wikipedia.org/wiki/Lines_per_inch
http://en.wikipedia.org/wiki/Halftone

And here's an alternate way to describe dpi, ppi, and lpi. IMHO a more accurate than the photo guide above:
http://desktoppub.about.com/cs/inter...resolution.htm

The thing is that higher resolution does not always increase the quality of the printed image and in order to keep the image size down (in mb) it's better with as low dpi as possible but still high enough (about two times the lpi).