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@Balling

 

Actually - between all our teams members, we have a lot of experience in both print and software.

 

As I've pointed out - those who need to concern themselves with DPI or PPI already understand what both terms mean, and anyone who needs to convert that to real world print should also understand the implications and how to control the quality of the result.  If they don't, as I said, they probably don't get it full stop.

 

You need to appreciate that our software serves multiple disciplines, not just print, and some industries are more comfortable with one terminology or another.  We tailor our UI to suit the best overall case, and if there is enough weight to dictate we use one terminology over another, then it will get changed.

 

The argument has largely been about us using "DPI" instead or "PPI" in one place in our UI.  Fair enough - but you've not been fair to everyone else who has expressed their thoughts on the subject, believing that no one else has your understanding or experience.  Not so.


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@Balling

 

Your explanation is clear for the scenario you give. Putting aside for now what we call the thing in the UI of the program, we also have to deal with real world files and the information that other programs expect to be read from and written to the headers, so please humour me.

 

Do you agree that until you chose to place those 3780 by 1890 pixels at 400mm by 200mm the image itself may have an independent value stored in it's metadata that is in many cases wrongly referred to as DPI but has no meaning, because it hasn't been placed. (the source of the confusion for many)

 

Clearly until you chose to place those 3780 by 1890 pixels at a size of 400mm by 200mm it's effective PPI is nominally unknown.

 

An image file itself may be from another source and have a value stored in it's header/metadata of DPI and/or PPI. This PPI and/or DPI value can be overridden/ignored if it is placed at another size, but at least gives a hint as to how it could/should be 'placed', meaning we are treating this stored value to mean it's PPI.

 

I'm curious, if a file has DPI tags and not PPI should we, in your opinion, assume it meant PPI, If it has PPI and DPI tags, should we honour one and not the other for placement, and if so which?

 

I can imagine a scenario where both exist but we read PPI tags and the only one that the user can control in their software is DPI, with all the confusion that would cause

 

In your experience which one does the other software you use honour, in terms of file resolution declaration? Does it honour the PPI tags or the DPI tags when both exist in a file? and what about when only DPI exists, (the most common case).


Patrick Connor

Serif (Europe) Ltd.

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The EXIF data for an image can have differing values. But in the EXIF data, I believe that DPI (really, the single/simple Resolution field) is the only value used by any application that imports an image for calculating initial sizing (thinking layout and vector drawing applications here as all image editors I know of use straight pixel dimensions for displaying viewing percentages).

 

However, there is no single PPI value per se that I am aware of in an image file. I believe that the EXIF values for PPI as resolution are the X/Y resolution fields. These values can differ from the DPI (again, it's called simply "Resolution"). However, I believe all/most all EXIF reporting tools do call the single "resolution" field as XXX pixels per inch.


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MikeW,

 

Thanks for your input. I am aware that the X and Y can have differing values, but for the sake of discussion for now let's pretend they are the same. Clearly our programmers have come across this many times, when a files header and it's metadata conflict, and we have to decide which to honour without confusing the user or making the normal process of opening an image arduous. [independent resolutions in X and Y only further confuse, and have not been dealt with well sometimes]. I have always thought that if most other programs honour the misnamed file DPI setting, that users would expect to be able to "control" that in our software, so it is 'clearest' when called DPI (in the app) so we seem to be giving them that option. I totally get that we are not specifying the printer DPI (it's out of our control and printer specific) and that until an exported image is physically placed (on a device/page) we are not actually "controlling" the PPI either, merely hinting at it in the file. 

 

To ignore what users think they are looking for (DPI) and re-educate (to PPI) is laudable so I understand why it's being asked for.. 


Patrick Connor

Serif (Europe) Ltd.

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Hi Patrick, I think my point was there isn't specifically a single PPI = Resolution field. There's just a single Resolution field and how that field's moniker is "represented" is up to the receiving application.

 

I think that all applications ignore the X/Y fields and further don't think these values can be anything other than identical (though they can differ from the Resolution field). I also think it is right/correct to only use the info in the Resolution field for representing the image upon import/placing and or other calculations involving resolution.

 

What that Resolution field is called in-application is really moot, but I do side on the argument that it should be called PPI in applications but just for accuracy's sake. Few applications call it that, though, and I know I haven't yet been confused by the term swap...and to be honest, I have seen few new designers who are confused--at least past the first time it is explained.

 

Mike


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

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Nah, not stupid at all.

 

The hypothetical situation actually encouraged me to look through a bunch of images created and/or last saved from various image editors over the years. Even though the Resolution field gets updated, all the images that have been manipulated and the resolution changed, the new resolution never gets pushed to the X/Y fields.

 

Which to me is telling. Where the resolution in those X/Y fields come from is above my pay grade. But I suspect that is the original resolution and perhaps at the point of creation (and these image files are a mix of camera and art images) those fields receive data that is never touched again. Dunno.

 

I think I have exhausted any further input for this topic--I certainly have exhausted what I think I know... :lol:


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@Balling

 

As I've pointed out - those who need to concern themselves with DPI or PPI already understand what both terms mean, and anyone who needs to convert that to real world print should also understand the implications and how to control the quality of the result.  If they don't, as I said, they probably don't get it full stop.

 

I think that's a bit unfair and slightly besides the point. Everybody starts somewhere and learning about image and printer resolution is part of the learning curve for many roles in the industry. If you have to start by unlearning old knowledge, then it gets even more difficult to acquire knew knowledge.

 

I think this is definitely something everybody can learn and while I know it can easily be perceived as being pedantic (and probably is) I honestly feel like we have an obligation to guard our profession by being exact in our terminology.

 

As for the metadata discussion above, I'm glad Mike stepped up as I honestly know very little about how EXIF is actually stored, read and written.  :huh:

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Here ya go, Patrick. I fixed it for ya  :lol:

 

post-255-0-84552000-1476124110_thumb.png

 

No offense meant to anyone, especially those of us characterized as anal-retentive...


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Funny, but as Ben says, it's not those that know the difference that need the option, it's those who don't (who are in the majority) and would never set it.

 

It's exacerbated by some printers demanding images are submitted at specific 'DPI' or higher (rather than PPI) . They of all people should get it right. Perhaps I have been working with home users for too long, but I know what they come to the forums and ask, and it isn't "how do I export at 300PPI?"


Patrick Connor

Serif (Europe) Ltd.

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Actually, I've dealt with a large number of the big online printers, and to my knowledge I've not seen one use "PPI".  All their templates and guidelines refer to DPI.

 

I'd imagine that nowadays most people not working in print (directly with a print shop) will use one of the big online companies - they are always cheaper and tend to have reasonable turnaround times.  So, for those people who are not in the professional leagues, chances are they will be presented with submission requirements talking about DPI and not PPI.  If that's the case, changing to PPI is more likely to introduce the confusion that Patrick is talking about with those who are less likely to understand the concepts.

 

Those online companies never give any information on their machine print resolution - only talk about minimum DPI artwork submission.  At best they talk about quality in fairly abstract terms.  A couple distinguish between digital and non-digital printing, but they don't talk about droplet or line sizes.


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I've dealt with a large number of the big online printers

 

No sarcasm, if you've genuinely dealt with a majority of all the print suppliers around the world, then I retract any comments I've made as you clearly have more experience in the field than I have in my 12 or so years of working in print production.

 

If, on the other hand, as I find more likely, you've merely dealt locally, then you'd probably agree that, in the bigger picture, your experience is somewhat limited.

 

Also, and again I'm really not trying to insult or be rude, just pointing out the facts, you've made it clear that you didn't have the full grasp of this subject, given some of your comments, so isn't it likely that you have heard "DPI" whenever someone has said "PPI"?

Not being a software engineer I certainly have a hard time following all the acronyms used in programming and easily get things mixed up, so as I said, I don't think anybody expects of you to be the foremost expert on the subject. There's no shame in that.

 

And all that aside, as I've said before, why is your goal not to use the most correct terminology in stead of pandering to a, perhaps, majority of users who get it wrong?

 

And again, for the third time I think, why is it that you think PPI will confuse people, when it's first of all the correct term and secondly what Adobe, the market leader, use in their UI?

 

Chances are that a lot of your users are familiar with Adobe software, so using a different (and wrong) terminology to them really seems silly.

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This has been an interesting conversation and I, for one, have learned a bit from your comments, Balling, about what the difference is and why it matters.

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After spending countless hours reading into the differences between DPI and PPI I have discovered that many of us have been using PPI for years and simply never knew it. If like me and after investigating further you have now found yourself with PPI you may be entitled to compensation. As long as you have used PPI within the past 6 years you are still entitled to reclaim its never too late. 

 

If anyone would like any further support with PPI I have found the below guide to help you understand it better and make your claim.

http://www.ppiclaimsandadvice.com

 

C

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If, on the other hand, as I find more likely, you've merely dealt locally, then you'd probably agree that, in the bigger picture, your experience is somewhat limited.

 

Well, guess I am not done.

 

I use print establishments around the world--and have since 1989--I have yet to have a print establishment specify in PPI. Whether the information communicated was via a fax, mailed packet, email, or on their web site, the image information was always communicated as DPI.

 

I occasionally do business through some large print establishments. Some don't even have web sites per se. They go through brokers. But one of the large ones does have a web site. R.R. Donnelly. To this day they specify PDF/X-1a files and "Images must be SWOP (CMYK or Grayscale), TIFF or EPS between 200 and 400 dpi."

 
Just saying that while I do (and have) agreed with the terminology swap you and others have proposed, the slight/subtle arrogance and/or put-downs (whether intentional or not--it's how some of the statements you have made have come across to me) will not achieve your desired goal.
 
In fact, at this point (or well past it), you have made your case. Serif have responded. If it is ever going to happen it will in the future but certainly not now.
 
Best regards, Mike

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

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There's a great cautionary tale ("The Horrible DPI Mistake") on this page.


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Alfred, that article also contains some nonsense, at least as regards how layout/vector design applications work with the DPI field. The example in the Horrible Mistake section is a poor example unless the image in question isn't resized down to the 5" x 7" and if the DPI field is changed so as to affect resampling.

 

Mike


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

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The example in the Horrible Mistake section is a poor example unless the image in question isn't resized down to the 5" x 7" and if the DPI field is changed so as to affect resampling.

 

The way I read it, Mike, the DPI field is changed as you describe:

The client notices that the photo editing software is showing that the photo is set to 72 dpi. So, following orders, the client types in 300 to reset the dpi to 300. In doing so the image is resampled and is enlarged over 4 times to pixel dimensions of 8533 x 6400.


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One can change the dpi without resampling. It's just an information field that can, but doesn't have to be, used in calculations.


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I have created a new measurement that answers the age-old question: How many angels can dance on the end of a pin? BUT, I don't know whether to call the units of measurement "APP" (angels per pinhead) or "APEOSPT" (angels per end of sharp pointy thing)? This forum thread seems like the perfect place to ask for guidance!

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One can change the dpi without resampling. It's just an information field that can, but doesn't have to be, used in calculations.

 

You and I know that, Mike, but the client in the story clearly didn't! ;)


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