3 ms·

Almost the opposite: my position is that there is a distinction but it's purely lexical, and the two terms are effectively synonymous. That's why it's not quite

by bonaldi 16y ago

Almost the opposite: my position is that there is a distinction but it's purely lexical, and the two terms are effectively synonymous. That's why it's not quite right to say that people "confuse" them all the time (as my grandparent did); it's more correct to say they're not as precise as you might want. You yourself show the interchangeable nature of dots and pixels when you say you measure the size of your display in dots, even though (assuming it's not CRT), it's very much measured in pixels, regardless of the resolution you've got your desktop set at. (This whole thing came about because of people saying Bray was wrong to measure his screen in dots, after all). tl;dr: you can insist on a distinction between dpi and ppi, but it doesn't really get you anything, and it definitely doesn't help people understand printing!

sesqu 16y ago
For clarification: LCD displays like mine have red, green and blue tinted light sources, arranged such that one of each combine to roughly a square. Other displays work similarly, except they don't have any squares. I consider each light source a dot, and when viewing images at 1 pixel per square (natural device resolution), I consider the square a pixel for convenience. So inches are what I measure the size of my display in, natural pixels per inch are what I measure the resolution of my display in, and dots per inch are what I would measure the resolution an arbitrary display device in, if it did not have a natural mapping between pixels and dots. So dpi is equivalent to 3ppi for LCD under my definition, and both 1ppi and 3*ppi dpi counts have been sighted in the wild. Using my definition is like using SI mibibytes; when you see dpi you don't know which is being measured, but when you see ppi you can be sure, since ppi is only used by people like me. As such, I do not consider dots and pixels interchangeable; pixels are what I'm trying to represent, dots are what I'm representing them with. If I'm dealing with a printer, I acknowledge that I'm not going to get neat square pixels no matter how hard I try; instead, I'll end up with round, scattered dots. So I look at the dpi of the printer and the ppi of the ideal representation of my image (in inches), and get something like 6 dots/pixel. I consider this sufficient to render a close approximation to a tiny square, and proceed (actually, I don't usually look at that number, since printer resolution is never a problem for me). This lets me focus on the one aspect of printing that actually matters to a computer: megapixels. As long as I keep the ppi ratio of my layout high, and trust that the printer has high dpi and proper scaling, I get to ignore stupidities like jpeg dpi metadata. In theory, anyway - occasionally print houses request specific dpi, which can be considered a ppi hint and used to do rescaling with the algorithm I want. Disclaimer: I've never done any print or layout work.

by bonaldi 16y ago

sesqu 16y ago

For clarification: LCD displays like mine have red, green and blue tinted light sources, arranged such that one of each combine to roughly a square. Other displays work similarly, except they don't have any squares. I consider each light source a dot, and when viewing images at 1 pixel per square (natural device resolution), I consider the square a pixel for convenience. So inches are what I measure the size of my display in, natural pixels per inch are what I measure the resolution of my display in, and dots per inch are what I would measure the resolution an arbitrary display device in, if it did not have a natural mapping between pixels and dots. So dpi is equivalent to 3ppi for LCD under my definition, and both 1ppi and 3*ppi dpi counts have been sighted in the wild. Using my definition is like using SI mibibytes; when you see dpi you don't know which is being measured, but when you see ppi you can be sure, since ppi is only used by people like me. As such, I do not consider dots and pixels interchangeable; pixels are what I'm trying to represent, dots are what I'm representing them with. If I'm dealing with a printer, I acknowledge that I'm not going to get neat square pixels no matter how hard I try; instead, I'll end up with round, scattered dots. So I look at the dpi of the printer and the ppi of the ideal representation of my image (in inches), and get something like 6 dots/pixel. I consider this sufficient to render a close approximation to a tiny square, and proceed (actually, I don't usually look at that number, since printer resolution is never a problem for me). This lets me focus on the one aspect of printing that actually matters to a computer: megapixels. As long as I keep the ppi ratio of my layout high, and trust that the printer has high dpi and proper scaling, I get to ignore stupidities like jpeg dpi metadata. In theory, anyway - occasionally print houses request specific dpi, which can be considered a ppi hint and used to do rescaling with the algorithm I want. Disclaimer: I've never done any print or layout work.