PDF opened as 300 dpi documents are NOT opened as 300 dpi documents

[joe_l]

At work I open a lot of PDF files having tables inside. Unfortunately these tables are not really tables when you open them and here is Serif not to blame. Maybe Serif proves me wrong, but here is what I strongly believe:

1) Open a PDF with 300 dpi (you can test this with the attached one) with options as you like.

2) Create a table in this document.

3) Select a word with the text cursor and drag it into a table cell.

Result: The dragged word in the table cell is now with a factor of about 4,17 smaller than the orginal word. Divide 300 by 4,17 and the result would be about 72.

MY conclusion: The opened PDF is somewhere "flagged" by APu to be treated as a 300 dpi, but the content is still 72 dpi. This could be the explanation why linking text frames in opened PDF lead to different font sizes in different text frames.

wotever.pdf

[joe_l]

You can test it with opening the PDF at 72 dpi and then dragging the word to the table cell. You will notice that the font size won't change. Does this mean, that it is the recommended workflow to open a PDF always at 72 dpi?

EDIT: Wouldn't that mean also that .idml files should always be opened at 72 dpi? With .idml I also had problems with different font sizes in text frames.

[Hangman]

Hi @joe_l,

To quote Dov Isaacs, former Adobe Principal Scientist "There is no concept of a PDF file having a single resolution. Resolution is not an attribute of a PDF file, but rather of each of the raster images therein."

9 minutes ago, joe_l said:

Wouldn't that mean also that .idml files should always be opened at 72 dpi?

They are and this has proved to be an issue, reported many times in the forums and logged under AF-1288 and AF-1342.

When opening your sample PDF in Affinity Apps, if you manually specify a dpi of 300 then create a table and drag the text into a table cell you are indeed seeing a conversion between a 72 dpi object and a 300 dpi object, in your example, 12pt text becomes 2.88pt text.

72 / 300 = 0.24 | 12pt x 0.24 = 2.88pt

Much the same as creating two Publisher documents both using Pixels as the unit of measurement, one at 72 dpi, the other at 300 dpi, create some 12pt text in the 72 dpi document then copy and paste it into the 300 dpi document and the text will appear at 2.88pt.

[joe_l]

3 minutes ago, Hangman said:

When opening your sample PDF in Affinity Apps, if you manually specify a dpi of 300 then create a table and drag the text into a table cell you are indeed seeing a conversion between a 72 dpi object and a 300 dpi object, in your example, 12pt text becomes 2.88pt text.

So would you say, that opening a PDF should have no choice setting up the DPI and instead open it fixed with 72 dpi? Opening a PDF exported at 300 dpi with 300 dpi images (which lose 1 dpi after opening the PDF, placed DPI is now 299) the resource manager will tell that the original DPI is 72.

[Hangman]

58 minutes ago, joe_l said:

So would you say, that opening a PDF should have no choice setting up the DPI and instead open it fixed with 72 dpi? Opening a PDF exported at 300 dpi with 300 dpi images (which lose 1 dpi after opening the PDF, placed DPI is now 299) the resource manager will tell that the original DPI is 72.

It's quite difficult to understand what is being shown in Resource Manager when opening a PDF file containing a 300 dpi image...

If I take a 4,016 px x 4,016px, 300 dpi JPEG file and Place it:

1. Unscaled in an A4 (2480.314961 px x 3,507.874016 px), 300 dpi Publisher document
2. Unscaled in an A4 (2480 px x 3,508 px), 300 dpi Publisher document
3. Unscaled in a Square 4,016 px x 4,016px, 300 dpi Publisher document

And export both using the same PDF export settings I see the following reported in Resource Manager when opening the exported PDF files in Publisher when using 'Estimate' for both DPI and Colour Space...

A4 file (Actual Size)
Original Size - 2,484 px x 3,511 px
Original DPI - 96
Placed Size - 2,484 px x 3,511 px
Placed DPI - 299
File Type - JPG

A4 file (Rounded Size)
Original Size - 2,482 px x 3,510 px
Original DPI - 96
Placed Size - 2,482 px x 3,510 px
Placed DPI - 299
File Type - JPG

3. Square file
Original Size - 4,016 px x 4,016 px
Original DPI - 300
Placed Size - 4,016 px x 4,016 px
Placed DPI - 300
File Type - JPG

 

• The A4 (Actual Size) file original and placed pixel sizes differ by 4 px in both width and height and the original dpi is shown as 96...
• The A4 (Rounded Size) file original and placed pixel sizes differ by 2 px in both width and height and the original dpi is shown as 96...
• The Square file original and placed pixel sizes match in both width and height and the original dpi is shown as 300...