The Ink Spot

6:45 AM

I wonder if the real problem behind DPI/PPI/LPI disussion is the fact that you need to have 2 models of how the world work that seemingly are in contradiction with each other.

I mean marketting people have stolen the idea that higher resolution or more PPI is better.

joojaa

7:06 AM

But the meaning of a value for a image is different than for a device.

So it is very easy to go into a trap with your thinking that you can not dig yourself out of.

Meta Graphic Design

8:14 AM

0

Q: Help me make a reference answer

I think I have figured out why the DPI/PPI/LPI/Pixel/resolution (for simplicity lets refer to all of these a DPI in this discussion) discussion always devolves in a very big problem. The problem is 3 fold: To understand this quickly one needs to be able to have 2 conflicting models of how thing...

discussion

PieBie

8:37 AM

@joojaa I agree, marketing really screwed up the whole resolution debate. And then Apple introduced pixel density and it got really f*cked

BESW

8:54 AM

I know I'm very confused about the whole thing.

I have a background in the arts, not computer sciences.

Even that meta post assumes knowledge I don't have.

joojaa

@BESW LIke what info?

@PieBie yeah.

BESW

Well, there's a lot of statements about what things aren't.

Not very much about what they actually are.

joojaa

The problem is usually that peoples expectation needs to be reset

Well trying to explain what they are is more difficult as it assumes you know quite lot of things

BESW

I also don't know what the two conflicting models are.

joojaa

@BESW DPI is just a number, that may or may not be relevant to what you are doing

BESW

8:59 AM

My college digital arts instructors taught me very much the things you're saying aren't the case.

joojaa

and that is the problem

DPI is a conversion factor, but for an image its nothing. Its not even part of the image

DPI is not a intrinisc property of an image

BESW

So... an image has the quality [number of dots], and DPI is the choice of how many of those dots to cram into a given area on the device displaying the image?

joojaa

An image has pixels and DPI is just a conversion factor to tell how you would like them crammed out to a PRINTER. DPI does not define quality of your image your pixels do

The critical point is that it only applies to a printer, and not even all printers

BESW

Ahah. That explains a lot; my primary digital arts instructor was a photographer who usually had physical media as his final medium.

joojaa

It does not apply to a image on screen. It does not apply to your export settings. It does not imply quality of a image.

BESW

9:07 AM

When you said "Images are fundamentally different from imaging devices!" I thought that implied pixels:images::dpi:imagingdevices.

joojaa

Well yes but not quite. Not all imaging devices are born equal

While monitors do undoubtedly have a PPI (DPI) value it does not actually affect your image in any way. YOu can not use that PPI info for anything other than a purchase info. If even that, because it also lies to quite many people.

In printing the question is about interpolation. A printer needs to interpolate your image data almost without a exception. So the DPI value is used by the interpolating engine to deduce how big to interpolate.

This leads to a somewhat weird relationship between (offset/laser) print quality and asked DPI. even so the DPI is not the source of the quality pixels are

BESW

I have no idea what you just said, I'm sorry. DPI is only for printers (do you mean companies that print things, or the machines people use to print things?) but that monitors have a DPI value.

joojaa

Yes monitor have a pitch between pixels

BESW

Then how is DPI not "for" monitors?

joojaa

equationg what is true for printer and monitor is one common source of problems

BESW

9:13 AM

And apparently I don't know what you mean by "imaging devices." Is that just light-based interfaces like monitors, or does it include printing machines?

joojaa

imaging device is any device that produces an image

Anyway DPI is not for monitors because we use them essentially differently

BESW

@joojaa You've said that. I hear you. But everything else you're saying seems to contradict it.

So there's something I'm not getting and I'm trying to re-state what I'm hearing in order to figure out where I'm confused.

@joojaa What is that essential difference?

joojaa

---
When you print your asking somebody/thing to manufacture a thing at certain specifications
---
When using monitors you are just using whatever device the user has. You have no control over the size of users devices.

You could decide ship your design to people on your own monitors but you hardly ever see this done. IN that case it would apply.

You can not specify that monitor so trying to write a specification is just irelevant tha end user will/can not comply.

So we approach the problem differently

BESW

So the difference between monitors and printers, for DPI, is a matter of locus of control rather than a physical difference in the machines themselves.

joojaa

basically... what makes sense in printing makes no sense on a monitor since you can not just reconfigure the hardware

BESW

9:20 AM

That's an important distinction to make.

So would it be accurate to say:
An image has the quality [number of dots], and DPI is the choice of how many of those dots to cram into a given area on the device displaying the image--but most of the time only physical printing devices let the creator of the image control that choice in a meaningful way.

joojaa

So we approach the problem differently. We treat each sample on this monitor as a sample on that monitor. Without accounting for any other thing. So 1 pixel is one pixel, the PPI is what it happens to be. The size is what it happens to be.

joojaa

And then we have apple retina displays.... oh dear.

BESW

I'm not sure what --- is representing.

joojaa

And now we can finaly come to the core of the issue DPI is not image quality. Pixels are image quality, DPI is just a tool for calculating how many pixels would be a good guesstimate

@BESW i am trying to make separate paragraphs stand out

if i do not they all become on big block of text

no meaning

BESW

Ahah.

Okay, so my understanding wasn't actually very far off. You're just coming at it from a very different direction than I usually do.

I think I have a more rounded comprehension now. I hope.

Thanks.

joojaa

9:29 AM

Well this is my curent thing in needing a ultimate explanation kind of thing

I have a few others but they have passed the perfected well enough marker

BESW

I might be able to help out; I've been practicing explaining pixels to laypeople for years, mostly in terms of raster vs vector art.

Ryan

1:18 PM

@DᴀʀᴛʜVᴀᴅᴇʀ heil helmet

DᴀʀᴛʜVᴀᴅᴇʀ

friday.. rar

how I am going to attack this friday:

Ryan

I got yelled at once already today and am ready to just get in my car and go home

DᴀʀᴛʜVᴀᴅᴇʀ

dang that sucks..

Ryan

it really does. need to not take their bad days out on me

DᴀʀᴛʜVᴀᴅᴇʀ

1:55 PM

@Ryan well man hope your day gets better. Im out in code land

JohnB

2:47 PM

merrrhh, it appears that Chrome has changed the color scheme for incognito mode and I do not like it >:(

PieBie

oh yeah, it's inverted now

Ryan

stop looking at questionable websites at work :P

JohnB

hahah I figured that'd be coming :D

Ryan

cat porn, hot!

JohnB

clash of the colors, that really looks terrible to me

at the very least match the scrollbar!

Ryan

2:53 PM

True, but it only applies to the print instructions. Its not a property of the image it is a property of your print! That is where things go horribly wrong 2. That is because animator never think of dpi its not applicable for any of their work. Aspect ratio is but that is trivial. — joojaa 5 mins ago

I don't understand his comment "Its not a property of the image it is a property of your print!"

JohnB

There are uses where PPI matters for software use

I answered a question about it once but finding it would be ~~difficult~~ not difficult at all

so of course that's what I'm going to do

2

A: With Photoshop CS5, how do you retain original size of an image dropped as a file into an open document?

This is because of the difference in PPI between the image you are placing and the PPI of your document. Here I've placed a 350 PPI image on a 72 PPI document: But if I place the same image on a 350 PPI document (same pixel dimensions, compare the rulers of each document): How you can fix ...

Ryan

I mean I explained why it matters, he said true. Then continued on it not mattering which is why I'm confused

JohnB

I guess that answer is a rebuttal to his 2nd point. Not all software ignores PPI

I think some image viewers (maybe on Mac?) use it as well, but I am not certain

this guy here says it does: meta.stackexchange.com/questions/275835/…

Ryan

I think the issue is his narrow definition of Image. Like in comment on the question he said, "placed in a page layout app" which begs the question are images created from desktop publishing apps not images :\

JohnB

Do you know what started the "rant"? I'm guessing there was a question by a misinformed user that lead to this

reading the chat, I guess I just disagree with the whole premise based on those two links I posted

PPI can be and does get used by some software but certainly not all

Ryan

3:08 PM

Nope, not a clue what led to it perhaps @PieBie knows

PieBie

see here:

2 days ago, by joojaa

Do we need a technical question and an answer for what a pixel is

JohnB

ah

PieBie

I think that's where it started

JohnB

I certainly have my own DPI/PPI gripes. It's not uncommon for people to ask for "300 DPI artwork"

...okay 300 DPI at what size?

but I usually don't ask and just send them the highest resolution available

Ryan

JohnB

3:14 PM

haha

usually the problem is it's technical info being passed along by someone doesn't know what it means and the important piece gets left out

Ryan

that Joojaa commented his ideas stem from Scott somewhat confirms to me what I said -- image definition matters

JohnB

I cringe a little every time my boss asks me again for what kind of artwork format I need so he can pass it along... oh god he's going to screw it up I just know it

Ryan

Scott and I had debated what constitutes graphic design and images

I really like the photo composite I developed for the cover of our new catalog but coming up with the rest of the design is proving obnoxious

PieBie

@Ryan well, If I read this answer I think you might be right

Transcript for