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When you import a PDF in Designer it brings up the "PDF Options" window, which has a DPI dropdown (which I'm slightly confused by the purpose of).

 

Per definition you can't adjust DPI (Drops Per Inch) on a file (drops of what?) so what you mean is probably PPI (Pixels Per Inch) which image resolution is measured in.

 

The relationship between PPI and DPI is source for confusion for a lot of designers, so IMO it's paramount that the software we use gets it right. :)

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Balling,

 

Welcome to the Serif Affinity Forums,  :)

 

Technically you are correct, but there is a widespread acceptance of the term DPI as being understood to mean PPI.

 

This thread covers this quite well, as does this and this and this and this, so you see you are not alone in asking and we do consider all user requests, so thank you.


Patrick Connor

Serif (Europe) Ltd.

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Very simply.

 

DPI (Dot per inch ) is for print. Think of half-tone patterns, that is how a print "prints". So I've if you are working on CMYK document that needs to printed. Use DPI. The print shop you use will almost always provide you with a ICC profile as well as a min and max DPI to insure good quality images.

 

PPI (Pixels per inch) is the opposite. It's relate to the screen. So if you are working on RGB document for screen and devices, go with PPI.

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@peterdanckwerts

Of course, you're right.

 

@Patrick Connor

Thanks for your reply.

 

"...there is a widespread acceptance..."

There is? Certainly not among professionals there isn't.

I'd say there's a widespread misconception and misunderstanding only made worse by software confusing the terms.

You're using the wrong term, there's no way around that.

 

@csj

I'm sorry, but everything you're saying is just completely wrong. Case in point that people don't understand these terms.

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I remember the days when we spec'ed out jobs with printers in terms of LPI – that's Lines per inch — I think PPI became fashionable once DPI came onto the scene and LPI felt dated, so they dropped it for PPI ;)


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I remember the days when we spec'ed out jobs with printers in terms of LPI – that's Lines per inch — I think PPI became fashionable once DPI came onto the scene and LPI felt dated, so they dropped it for PPI ;)

 

Er, LPI is still relevant with traditional film, direct to plate (or, computer to plate) technology, and most (if not all) digital presses. With the mentioned print technology, we all still discuss and specify appropriate LPI for a given job.

 

LPI is not equivalent to PPI.


My computer is a nothing-special Toshiba laptop with unremarkable specs running Windows 10 64-bit.

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@csj

I'm sorry, but everything you're saying is just completely wrong. Case in point that people don't understand these terms.

 

I think I'm going to have to agree with csj.   Regardless of what you think those terms meant in the past, all software I have ever used, and every print shop I have ever dealt with, used DPI to mean Dots Per Inch related to print resolution.  It's a metric of image quality over real space when printing.

 

With the move to digital displays being expressed more in points (as opposed to pixels), there is a reasonable correlation between DPI and PPI.  It's largely assumed that these can be used interchangeably since they amount to the same thing when projecting an image into physical space (on a screen or onto paper).  Anyone who really understands this doesn't worry themselves about the (very slight) infringement of terminology.


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@Ben

 

I'm sorry, genuinely not trying to be a nusance, but if you make graphics design software you REALLY need to read up on this.

 

What CSJ is saying is just utter nonsense. There's simply no correlation AT ALL between image resolution, printer resolution and colour space. If you think DPI and PPI have something to do with CMYK and RGB, then you're getting a lot of things mixed up. They completely unrelated. Just like DPI and PPI.

And "PPI is the opposite of DPI", what? And you're "going to have to agree with this"?

 

Start here: http://www.andrewdaceyphotography.com/articles/dpi/

And here: https://99designs.dk/blog/tips/ppi-vs-dpi-whats-the-difference/

 

Like I said there is a widespread misunderstanding, which means that, as you say, even professionals and print shops mix things up.

 

First of all, there's no two ways around this. Either you want to have the correct term in your software (like Adobe has) or you don't, that's completely up to you.

 

Second of all, let me try to explain why I think it's important that you use the correct terms.

 

In our print shop we have inkjet printers capable of outputting print at 360 to 1080 DPI. This is pretty standard.

 

When presented with this fact MANY (especially young) designers are thoroughly confused as they have the notion that DPI is something they control in their software and that they somehow have to "match" our printers DPI setting.

 

A finished printed image will always have both a PPI and DPI resolution. I can print a 100 PPI image @ 1080 DPI and a 300 PPI image @ 540 DPI.

Printing a 300 PPI image @ 540 DPI would make very little sense, something you'll see right away if you understand that (and indeed how) the two are different.

 

Printing a 300 DPI image @ 540 DPI on the other hand... Well that just makes zero sense to anyone. How could a print ever be both 300 DPI and 540 DPI?

 

This gets REALLY confusing if software (and indeed the people who make it) use the wrong terms.

 

Again, I realise I sound like a dick (which I guess is par for the course given your ironic "anyone who really understands this" comment), but I'm 100% certain that if you read up on these subjects, you'll see straight away that you can't just decide to use DPI in stead of PPI.

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@Balling, You're technically correct, but it honestly feels like splitting hairs.

 

Every print shop I've worked with request a file at 300dpi... to achieve what they're asking for I create a document at 300ppi in PS/Ai/iD. The term dpi may be used incorrectly here, but in the 15 years I've been in design I've never once had a print shop ask for a file using the correct terminology. Correcting them would probably just make me look like a smug twat.

 

Designers don't have to worry about dpi unless they're the ones printing, but creating a document at 300 ppi or dpi (depending on your design software) is achieving what the print shop is asking for.

 

Kudos to you for learning and using the correct terminology (genuinely, not sarcastically), but changing dpi to ppi in Affinity's UI probably isn't going to make or break anything other than being technically correct.

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@Brian

 

While you're right that designers perhaps don't need to worry about DPI, it's still a term they're likely to be confronted with when dealing with a printer or scanner or when communicating with a print shop. As per my example above, it's going to be near on impossible to understand why a print shop would offer you a 720 or 1080 DPI output, when you produced your file at say 240 DPI. If your software had correctly stated PPI, it'd be easier to grasp that you were dealing with two very different values.

 

The scanner is another good example, actually. Say you scan something at 2000 DPI and then open the scan in Affinity and it's only 300 DPI. You'd think the scanner was broken. If Affinity said 300 PPI, again it'd help you grasp you were dealing with different things.

 

I'm sorry that the print shops you've worked with haven't had a more professional approach. It's paramount to us to make sure that our clients get exactly the quality they need, but don't pay for a quality that's excessive to their needs. To hit this sweet spot we have a lot of talks with designers and photographers about, among many things, DPI and PPI as we want to make sure they know exactly what product they're buying and why it's the right choice for them.

 

Currently we're in the process of making a physical "viewing distance" diagram with the same photo printed in, on one axis, different PPI and at, on the other axis, different DPI. This will help people understand how much you can get away with at even relatively small distances. A photo in 40 PPI can be indistinguishable from one in 300 PPI when printed at 540 DPI and viewed at a couple of meters distance.

 

By the way, PPI only affects raster while DPI affects both raster and vector (as the vector is rasterised when printed). Another significant difference, that people are confused about when they think DPI has something to with image resolution only (and sometimes even image quality, as someone incorrectly stated above - a terrible quality image can still have a high PPI).

 

I think this debate ultimately comes down to the philosophy of the people making the software, really. Do they want it to be "close to the mark" or flat out correct?

 

I honestly only made this topic because I had the impression that the people behind the Affinity software were the sort of pedantic nerds, like me, that wanted everything to be spot on. Doing a search/replace for DPI/PPI seems a tiny job to solve and error that, as Patrick pointed out, a lot of people have noticed.

 

After downloading the Affinity Designer trial to see if it's a piece of software that could have a home in a professional print production, the mistakenly used DPI where they clearly meant PPI was literally my first impression. That just seems a shame.

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@Ben

 

I'm sorry, genuinely not trying to be a nusance, but if you make graphics design software you REALLY need to read up on this.

 

What CSJ is saying is just utter nonsense. There's simply no correlation AT ALL between image resolution, printer resolution and colour space. If you think DPI and PPI have something to do with CMYK and RGB, then you're getting a lot of things mixed up. They completely unrelated. Just like DPI and PPI.

And "PPI is the opposite of DPI", what? And you're "going to have to agree with this"?

 

I think you've missed what he was saying.  He wasn't saying the colour space and DPI is a connected concept, but that print shops will specify artwork should be provided with a minimum DPI, and using a preferred colour profile.

 

Forget the bit about colour profiles, and the bit he said about DPI is still largely correct.


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...the bit he said about DPI is still largely correct.

 

Not really, no.

 

Here's what he said about DPI.

 

"DPI (Dot per inch ) is for print. Think of half-tone patterns, that is how a print "prints"."

Yes, printers use Dots Per Inch to print. Agree so far.

 

"if you are working on CMYK document that needs to printed. Use DPI."

No, you don't use either DPI or PPI. If you're printing images, you inherently use both. It's not a choice. Whether it's CMYK or not has nothing at all to do with it. Nada.

 

"The print shop you use will almost always provide [...] a min and max DPI..."

They might provide that, but they'd be bad at their job in that case.

A qualified printshop will ask you what DPI you wish your prints printed at. At a given DPI and a given viewing distance (vd) a certain PPI will be sufficient for your job. This is common math that makes no sense if you incorrectly use DPI for both values.

 

Seriously, there's no argument here. You're using the wrong term.

 

I feel like I'm missing something here. Is there a bigger reason why you won't change this? It's not like I'm saying the software is terrible, so you don't have to admit defeat. There's an error, that's all. It's a common error, sure, but an error none the less.

 

Patrick linked to several threads where users have pointed out this error and in each thread there's staff members weakly defending the "choice" to use DPI by pointing at other software that does the same and arguing that "they're largely the same".

 

I've explained why they're not largely the same and even linked to articles describing the differences and why it's important to know and understand these differences.

 

It's obviously not important to a software engineer, UI designer or hobby photographer, but it's certainly important for people producing files for print production, which is a segment I, perhaps wrongly, had the impression you were aiming for as well.

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@Balling,

 

I think that by injecting large format work (i.e., the viewable distance resolution info) it is not helping your case.

 

In the end, Serif is not going to change how they are using DPI in concordance with other software. And while I agree with you as far as terminology goes, I have to say how they are using it is perfectly understandable by me, you and just about every other person using vector-based software or image editors. That it is not correct terminology doesn't matter in the end if what is displayed on-screen is accurate as regards the numbers. And those numbers are accurate. And those numbers agree with Acrobat's reporting of those numbers and every piece of pre-press software I have used.

 

And a second in the end...I think there are far larger fishes to fry as regards AD--and about every other piece of software I use day in and day out to change the terminology at this point.

 

Well, and a third in the end. If Serif (and other software makers) changed the terminology regards PPI versus DPI. they would generate a lot of support questions and statements like "why cannot your software use the same terminology as other software."

 

Best regards, Mike


My computer is a nothing-special Toshiba laptop with unremarkable specs running Windows 10 64-bit.

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@Mike

 

"I think that by injecting large format work (i.e., the viewable distance resolution info) it is not helping your case."

Could you elaborate? Small format printer and big format printers alike use DPI.

 

"how they are using it is perfectly understandable"

I've never questioned that. I knew straight away that what they meant was PPI, hence making this post.

It should honestly be very clear from this and the other forum posts that a lot of people who use (or make) graphics software don't fully understand this subject. Using the right terms in software would greatly help in this regard.

 

"I think there are far larger fishes to fry as regards AD"

Can't comment on that and I wasn't trying to imply that this is the biggest error in the software. Just that it's an error.

I'm completely fine with Serif deciding this is not something they want to fix, that it's an error they don't mind in their software.

I'm also fine with them giving it a low priority, that's not my business and I've no clue how difficult a task it is to replace a single letter however many places in the UI (not very, is my guess).

I'm a bit confused though, by their apparent attempt to claim that this is in fact not an error and not the wrong term.

 

"If Serif (and other software makers) changed the terminology regards PPI versus DPI. they would generate a lot of support questions"

So you're argument is literally that people are so confused by this that using the correct terms would raise support questions? That's a bit silly.

And I honestly don't think Adobe, who use PPI in all their software, are flooded with questions from people who don't get this.

 

Btw, Adobe used to have this exact error in their software 10-15 years ago, but they admitted it was an error and fixed it.

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...I'm a bit confused though, by their apparent attempt to claim that this is in fact not an error and not the wrong term.

 

 

Whose apparent attempt to do what exactly?

 

Well I think I was saying that we are technically wrong, but as most users understood our intent we weren't going to change it right now. I'll go back and read the whole thread again (and the other 4/5 threads), but perhaps you can save me the trouble and show me where Serif said PPI wasn't the technically right term.


Patrick Connor

Serif (Europe) Ltd.

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@Balling,

 

re Viewable distance and print resolution. Yes, the issue of print resolution is identical between large format and non-large format printing. But because there is a formula involved in calculating the required print resolution based upon the viewable distance, I think that throwing this aspect discussion into this concerning terminology one just adds more info than the simple issue of correct terminology.

 

The Knoll brothers began this myth with the first version of PS. Adobe perpetuated it for years. It's pretty ingrained and I have yet to review design curricular where correct terminology is used. It is possible correct terms are used in the actual class as a side matter, but the incorrect terms are still being taught. And this issue does come up on the Adobe forums frequently enough. But yes, Adobe did finally change the terminology. And some software makers used correct terminology all along. But there is far more software that has come and gone and some still around that has not used the correct terms.

 

But Serif hasn't and that's the really issue at hand. Don't get me wrong. I do wish that Serif would do so, and add in the terms actual & effective ppi in the process.


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Whose apparent attempt to do what exactly?

 

Well I think I was saying that we are technically wrong, but as most users understood our intent we weren't going to change it right now. I'll go back and read the whole thread again (and the other 4/5 threads), but perhaps you can save me the trouble and show me where Serif said PPI wasn't the technically right term.

 

"we weren't going to change it right now"

If you have plans to change it, and hence now it to be wrong, why didn't you just lead with that?

 

Just by using the word "technically" in this case, you're painting the thing in shades of grey.

 

They're different. Not somewhat different, a little different or sort of the same. The terms are completely, flat out different.

 

And certainly, as you request, here are some quotes from Serif staff being wrong about this subject.

 

"there is a widespread acceptance of the term DPI as being understood to mean PPI"

Nope. Not true. Certainly in your office there is, but in the world of professional print production? No.

 

"Regardless of what you think those terms meant in the past"

The meaning never changed.

 

"there is a reasonable correlation between DPI and PPI.  It's largely assumed that these can be used interchangeably"

That's a silly assumption. It's also wrong.

 

"We use DPI because we don't know if you're going to print the document or export it as an image. If you print, then DPI = DPI, if you export, then DPI = PPI. Hence why we said the terms are used interchangeably across most software packages."

That makes no sense.

 

"It may take some time to convince Microsoft to change their Explorer File > Properties > Details from displaying Horizontal and Vertical resolution in DPI, it may even be futile."

Well isn't that a shallow argument?

 

"we have deliberately used DPI and it is not an error"

Well sure it's an error, you just don't know it.

 

"It would need to change to say DPI/PPI each time the units changed between screen or physical types"

What? No, that's not at all how it works. It's always PPI. Your software doesn't need a DPI setting, ever.

 

"and what if you are creating a document for print that is not measured in pixels"

I don't even know what point this is supposed to make.

 

So there, I trawled through you guys not understanding the subject, now please, honestly, take the time to read up on this (I provided two useful links in my second post). I assure you, as soon as you do, you'll see why the distinction is important.

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@Balling, https://99designs.dk/blog/tips/ppi-vs-dpi-whats-the-difference/

that link has an error in the DPI section

the picture where a computer and a printer are compared and below the computer there are solid pixels and below the printer there are pixels containing the dots. But to be fair the computer should habe the R G B "dots" as well and not solid pixels  :P  at least when you actually look at it - not when they´re stored

 

 

after all I´m inclined to think Affinity should change DPI to PPI, (although I also was one of those people saying DPI = PPI)

 

https://www.youtube.com/watch?v=8S2cnZ2QR70 that link was given in some other thread and is the best explanation I´ve seen


 

 

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@Balling, https://99designs.dk/blog/tips/ppi-vs-dpi-whats-the-difference/

that link has an error in the DPI section

the picture where a computer and a printer are compared and below the computer there are solid pixels and below the printer there are pixels containing the dots. But to be fair the computer should habe the R G B "dots" as well and not solid pixels  :P  at least when you actually look at it - not when they´re stored

 

I think calling that an error is a bit of a stretch.

 

Showing the display configuration would confuse the point. Remember, not all displays (though the vast majority) have a traditional RGB configuration (opposed to PenTile or RGBw), so currently the diagrams on the page are correct, regardless of display type.

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@Balling

 

At the end of the day DPI, PPI, or whatever you want to call it is just a number.  It doesn't change how many physical pixels you have in your document - though it will effect rasterisation of non-pixel content.  It is interpreted to have meaning depending only by the end use of whatever image you are producing.  Anyone who has to concern themselves with DPI (or PPI) will understand that it is completely separate to the physical media scale on which it is printed or displayed, or the sub-pitch of the ink dots that the hardware produces.  These people who you say get confused by DPI and PPI will no doubt still be confused whatever we call it... perhaps they are in the wrong job.


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At the end of the day DPI, PPI, or whatever you want to call it is just a number.  It doesn't change how many physical pixels you have in your document - though it will effect rasterisation of non-pixel content....

 

 

Alleluja!


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@Balling

 

At the end of the day DPI, PPI, or whatever you want to call it is just a number.  It doesn't change how many physical pixels you have in your document - though it will effect rasterisation of non-pixel content.  It is interpreted to have meaning depending only by the end use of whatever image you are producing.  Anyone who has to concern themselves with DPI (or PPI) will understand that it is completely separate to the physical media scale on which it is printed or displayed, or the sub-pitch of the ink dots that the hardware produces.  These people who you say get confused by DPI and PPI will no doubt still be confused whatever we call it... perhaps they are in the wrong job.

 

What a weird experience this is.

 

Here I am, pointing at something that's clearly, no doubt about it, an error in your software (and I'm not the first to point this out, I might add), yet you guys are trying to alternately downplay it as insignificant or downright defend it as not being an error.

 

So far, your only arguments have been to point at other software and people making the same mistake. That's the only argument I've seen.

 

I'm curious if you've even read the explanations I've given and the links I've provided?

 

Do you have any comments on the many quotes where your team is making it clear they don't understand this?

 

That's really what I don't get. You, yourself, is a software engineer. I don't think anybody expects of you to know this subject (I mean that as in "it's not your field" not in any way that would imply prejudice against software engineers), yet you seem hell bent on defending a decision that was clearly made from an unenlightened point of view. Now that you're enlightened, you seem like it would be a personal defeat to admit the mistake.

 

You might think this subject is unimportant to your user base, yet the people pointing this out are inherently your users.

 

I honestly thought you guys wanted every little detail to be perfect, which I'll admit was completely my own mistake.

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Oh, and regarding the slightly odd "it is just a number" comment, try looking at it this way.

 

Say you receive an image that needs to be placed in a layout.

 

The image is 3780 x 1890 px and you want to scale it to 400 x 200 mm.

 

This leaves the image at 240 PPI.

 

Now, you can't change any of these numbers. The size is set and so are the pixel dimension of the image (bar interpolation, but let's ignore that for now). Hence the PPI is set as well. All of these values are out of your control at this point.

 

However, the DPI you do have control over and it does affect image quality.

 

You can now choose to print your image at whatever DPI settings your printer (or supplier) allows. It won't change the image, it won't change the size, yet it will change the quality.

 

Do you honestly not think this distinction is important?

 

I've seen SO many people who honestly think they have to make a 540 PPI image to print at 540 DPI resolution and are completely confused why this isn't the case.

Understandably so, I might add, given that the people they talk to and perhaps even the software they use confuse the terms.

 

I'm curious if this makes sense? Maybe I'm explaining myself poorly. It's worth adding this is a second language to me, so there might be a barrier there, I don't know...

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