jan_golfkarton's profile

14 Messages

 • 

264 Points

Sat, Dec 1, 2018 2:46 PM

Lightroom Classic: Pixels per inch not possible

LR Classic CC has (when you export a file) the option "Resolution - ___Pixels per inch". But why? A digital file does NOT have a size in inches.
I would remove that option because it does not make any sense.

Responses

128 Messages

 • 

1.8K Points

3 y ago

It is indeed only a property of the output-device (printer, screen), NOT of the digital image. Everywhere I see this strange discussion emerging...

14 Messages

 • 

264 Points

3 y ago

I am not quite sure what you mean. You can export the file to 1) email 2) Harddrive and 3) CD, but not to a printer. The "Resolution" option is underneath "Image sizing", but it what ever one fills out, it does not influence the size of the image.

Champion

 • 

1K Messages

 • 

15.9K Points

3 y ago

I don't know why people get hung up on digital files not having inch dimensions so by extrapolation then get rid of the dpi/ppi setting.   There are at least a couple uses for that option and I am sure several more..

1) The digital file may be printed at a lab.   If you want a file at 300dpi and 8x10 inches you can enter those numbers and Lightroom will do the calculations for you.

2) When you use digital files in some other programs the dpi/ppi value is used to size the file in the other program.


14 Messages

 • 

264 Points

1) A file is composed of pixels - NOTHING else. The thing is LR does not change anything when you change the pixels/inch setting.2) A file does not have any dot.

Champion

 • 

1K Messages

 • 

15.9K Points

I think you missed the whole point of the uses for ppi/dpi in the export dialog.

1) actually a file contains a LOT more info than pixels and one of them can be PPI or whatever the "official" metatag is that other programs use to initially handle the file on import.

2.3K Messages

 • 

26.4K Points

Exactly, like printing (out of Photoshop among many other applications). 
Or the OP can assume everything is 72"DPI" as we've seen in the past and isn't at all useful or accurate. 

Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

25 Messages

 • 

506 Points

3 y ago

This setting does indeed have a meaning even if it does not (directly) change the pixel content of the file.

Firstly, this may simply be another way to set the properties of the digital image which is output - but it may also an indication of the INTENT behind a particular outputting of the digital image - of its usage and purpose.

If you type in 1600 pixels wide (and 400ppi, or 4ppi), this is effectively the same thing so far as the pixel dimensions alone, as typing in 16 inches wide and 100 pixels per inch - or someother combination.

However setting 400ppi denotes an image which is envisaged (intentionally, or incidentally) to be printed to a smallish size range, and 4ppi denotes billboard size. 

How does this envisaged sizing matter?

It matters to Lightroom itself, for one: if you set output sharpening, this will happen differently (different picture content resulting in those two cases) even if the pixel dimensions remain the same. In Photoshop also, if you zoom the image to "print size" on screen; or if you use a physical size related means of cropping/converting or printing.

Another difference comes, with the placement of the digital image into other page layout software, or a similar technical / prepress workflow. Here physical scale is often intrinsic to the working method. For example: commonly a screen-resolution preview is made internally @ say 72ppi. If this image starts @ 4ppi, a 72ppi preview version will turn out much larger than the image itself; affecting file size etc for the working document. If it starts @ 400ppi, the 72ppi preview's a more useful and sensible version of that.

Hence a certain PPI is often asked for as well as a certain pixel dimension; and this is a good idea to deliver, EVEN IF the means one is actually using to determine these pixel dimensions in the first place, is by typing them in directly. 

14 Messages

 • 

264 Points

As I said before in other comments, a digital file is composed of pixels. - nothing else. When you change the setting "Pixels per inch" it does not change anything in LR (in PS yes, but then it is called upsampling). That is why I posed the question.Of course I realize the effect of number of pixels in relation to the size of a print, but LR does not know - so to speak - the size of my print.

25 Messages

 • 

506 Points

BTW changing PPI in Photoshop does not need to involve any upsampling (or downsampling) of the pixels. One can just change Resolution: the notional print size duly alters - when Resample is unchecked.

Even though it's not pixel data per se, PPI metadata IS a required property for a digital image, even more so than its colourspace metadata is. A digital file composed solely of pixels and truly "nothing else", could only be opened in PS by guessing at this missing metadata. For example, PS has got a raw file import utility (nothing to do with camera Raw).

Lightroom DOES know presumed sizing for your output, so far as that has been expressed in the PPI figure given during export. It is not possible to put no PPI whatever (it is only possible to not care what this figure is). LR can't know whether you agree with this notional sizing, but that's not really the software's fault: it is only following the available clues in a logical manner.

And this sizing then affects the output sharpening (if used). That's because it declares the particular (physical scaled) target circumstances which this sharpening should address. And this in turn changes, slightly, the actual pixels included in the output file.

2.3K Messages

 • 

26.4K Points

3 y ago

The setting absolutely has a meaning and is necessary. You could argue that the metric (inches) should be something else like millimeters or centimeters or even the old Rez (rez 12 etc). The file is made up of pixels so pixels per whatever makes total sense. Using 'dots' wouldn't be technically correct. We need to know the pixel density we desire so pixels per inch tells us this critical information. Again, you might wish pixels per mm but none the less, Adobe absolutely shouldn't take your suggestion to remove this. 
You seem to need a primer on resolution:
http://www.digitaldog.net/files/Resolution.pdf

14 Messages

 • 

264 Points

The is no such things as "pixel density". A file is composed of pixels - nothing else. 

45 Messages

 • 

716 Points

A file has lots of metadata not just pixels!  Just do a little learning online.

2.3K Messages

 • 

26.4K Points

Of course there's pixel density! You have an image that's 1200x800 as an example. That's the pixel density. Now you want to print it. You need to understand how to divide up those pixels for output: at 300 dpi, you'd have a 4 inch print. 
Again, you don't seem to understand the basic fundamentals of resolution. 
And yes, digital images are composed of pixels not dots; duh. That's why LR uses the metric: PIXELS per inch. 

Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

14 Messages

 • 

264 Points

Once you print you can check the number of pixels per inch/cm, but then you must know the size of your print (and LR does not know so to speak). Is this what you mean by "pixel density", then I agree.
But here is no "density" in a digital file. 

14 Messages

 • 

264 Points

Ryan: do you agree a digital file is composed of pixels? I said "nothing else" in the context of "pixels per inch".

45 Messages

 • 

716 Points

3 y ago

You do realize digital files can be printed correct? 

14 Messages

 • 

264 Points

Yes, but why the question?

2.3K Messages

 • 

26.4K Points

>>Yes, but why the question?
You were told why. 
There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.” 

― Søren Kierkegaard



Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

Champion

 • 

1K Messages

 • 

15.9K Points

Dolf
If you don't understand the uses of PPI in the export dialog than don't use it but Adobe shouldn't remove it for us users that do understand the usefulness of it.

14 Messages

 • 

264 Points

Tell me how exactly it affects the digital file when you use PPI and then I might understand you.

Champion

 • 

1K Messages

 • 

15.9K Points

This has been explained in detail by others on this thread.  As Andrew said, Adobe is NOT going to remove this settings so just don't use it.  I personally use it a lot for both sending print files to a lab and sending files to Photoshop

29 Messages

 • 

518 Points

3 y ago

It's all been said above and there's probably no need to stir the pot but the option does make sense and it shouldn't be removed. I use it frequently. Indeed, I have constructed a collection of presets that are built around its use and I'd be a little miffed if the option were removed.

128 Messages

 • 

1.8K Points

3 y ago

Test for yourself. Save a file with just 1 PPI, and save the same file with 100000 PPI. Compare the results. There is no difference!! So this is a useless option!

2.3K Messages

 • 

26.4K Points

You clearly have no idea what the metadata tag in the document provides despite the extensive text informing the OP above. 
You have 1000 pixels. How long will the print on that one axis? 
You NOW have 1000 pixels and the tag is set for 1 PPI and 1000PPI; NOW you know IF you printed this as such. 
Or, you and the OP believe that the tag is useless and there for no reason, that Adobe and many other imaging software products provide the tag for unknown and magical purposes. 

Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

14 Messages

 • 

264 Points

Ruurd: this is EXACTLY my point! So why does LR feature this option?

128 Messages

 • 

1.8K Points

Yes, but that is a argue to think about whence  you are to print your image. It is NOT a property of your image file, and hence no reason to add it to it, even not as metadata.

128 Messages

 • 

1.8K Points

2.3K Messages

 • 

26.4K Points

Yes that is exactly why; to OUTPUT the image and not necessarily to a print. Got a Display? Care about the size it outputs? You two are utterly confused about why the tag exists and when or why it’s used!

Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com)

29 Messages

 • 

518 Points

3 y ago

People, people, people. This is not Facebook... Please don't behave as if it is. Those of you who have an interest in continuing to lob thought grenades at each other, exchange email addresses and do it somewhere else.  Thanks 

Champion

 • 

6.7K Messages

 • 

112K Points

3 y ago

Would it be possible to manage without being able to set it in the Export dialog? Yes, because it's just descriptive metadata.

But would that be advantageous? No. Because apart from anything else, when deciding to output a file for print, most people would need to get a calculator out, and the dialog saves you doing that. 

There's a bunch more technical reasons why that metadata tag is useful/important, but even at a simple level it's useful.

Champion

 • 

2.4K Messages

 • 

39.2K Points

3 y ago

Victoria has hit the proverbial "nail on the head" and I'll help to drive it home!

While it's true camera files have no real PPI definition this is not the case for scanner image files and perhaps exported files edited for a specific printer and paper size. More at the below link:

https://feedback.photoshop.com/photoshop_family/topics/gw73zjy55amnv

Executive Summary
Scanner image files contain the actual physical dimensions of the captured negative, transparency, photograph, or other 2D document. This file metadata information allows accurate display and print of photograph and other paper document scan image files at a specific target ppi in their actual life-size dimensions. For film scan images it provides a record of the original negative or transparency dimensions enabling identification of the camera format size (i.e. 35mm, 2 1/4, 4x5, 8x10, etc.). This information is required for archival purposes and allows creating and applying Lightroom Develop presets designed for specific film types.

Peace on Earth Fellow Photoshop Family