APub Export PDF for Saal Digital

[davide_m]

Hi all,

in the latest few months I have been designed photobooks using APub with the aim of printing them through Saal Digital. The creation of the photobook is fine: I follow the dimensions defined by Saal Digital in their Professional Zone. Then, I need to export two PDFs: one for the internal pages and one for the cover. Saal Digital provides instructions on how to export files with InDesing or Photoshop, but not for APub (https://www.saal-digital.com/service/professional-zone/create-your-files-in-indesign/ -> scroll down to PDF Export).

These are the recommended settings for InDesign by Saal Digital:

 

And this is how I tried to replicate such settings:

The problem is that, upon printing of the file, everything that was centred is no longer centred and there is a slight offset towards the right. I attach here an example APub file for a cover where you can see that the vertical text is centred in the middle of the spine

This sample file is for a cover is of a 21x28 cm (8.5x11) photobook, with padded cover and 70 internal pages. The dimensions reported by Saal Digital are the following ones:

- Size: 465.4 x 288 mm (5497 x 3402 pixels with 300 DPI)

- Bleed left/right: 9.3 mm (110 pixels)

- Bleed top/bottom: 7 mm (83 pixels)

Thus, the size of the document in APub is: (465,4-(9,3x2)) x (288-(7x2)) = 446,8 x 274 mm. However, if I try to set the units of the document to pixels, in APub I get the following size: 5277,2 x 3236,2 px but instead it should be (5497-(110x2))x(3402-(83x2))=5277x3236 px (I don't know if this is related to the problem that I'm experiencing).

However, upon printing the result is the one shown in the picture below, and it is clearly visible that the text is not on the centre but it is slightly moved to the right (in the picture towards the bottom).

I tried to contact Saal Digital but they were of no help. Do you have any suggestion to avoid this issue in the export process?

Thanks a lot for your help!

Davide

Cover_Export_Issue.afpub

[Dan C]

Hi @davide_m!

4 hours ago, davide_m said:

This sample file is for a cover is of a 21x28 cm (8.5x11) photobook, with padded cover and 70 internal pages. The dimensions reported by Saal Digital are the following ones:

- Size: 465.4 x 288 mm (5497 x 3402 pixels with 300 DPI)

- Bleed left/right: 9.3 mm (110 pixels)

- Bleed top/bottom: 7 mm (83 pixels)

Thus, the size of the document in APub is: (465,4-(9,3x2)) x (288-(7x2)) = 446,8 x 274 mm. However, if I try to set the units of the document to pixels, in APub I get the following size: 5277,2 x 3236,2 px but instead it should be (5497-(110x2))x(3402-(83x2))=5277x3236 px (I don't know if this is related to the problem that I'm experiencing).

Unfortunately the conversion between Pixels and mm is not this exact - assuming 300DPI, 110px = 9.313333 mm and 83px = 7.027333 mm, therefore rounding is due to occur when converting.

Equally, the PDF export in Affinity is calculated internally in Pixels, and any part values are rounded to the nearest whole pixel value, which may also cause a slight size difference when exporting.

Therefore I'd recommend creating the document using the exact Pixel dimensions, to avoid any conversion rounding. Please see the example document attached at these exact pixel values.

I hope this clears things up

Cover_Export_Issue_rs.afpub

[davide_m]

9 hours ago, Dan C said:

Unfortunately the conversion between Pixels and mm is not this exact - assuming 300DPI, 110px = 9.313333 mm and 83px = 7.027333 mm, therefore rounding is due to occur when converting.

Equally, the PDF export in Affinity is calculated internally in Pixels, and any part values are rounded to the nearest whole pixel value, which may also cause a slight size difference when exporting.

Thank you so much for your reply @Dan C! I will for sure only use pixels as units in my photobook documents. 

By any chance, do you know if, in the PDF export settings, the APub "Include Bleed" option is the same as InDesign "Use Document Bleed Settings"? In this way I can exactly replicate what Saal Digital is describing in the export process for PDFs.

Thanks again!

Davide

[Dan C]

No problem at all!

12 hours ago, davide_m said:

By any chance, do you know if, in the PDF export settings, the APub "Include Bleed" option is the same as InDesign "Use Document Bleed Settings"

I haven't personally used this setting in InDesign before, however searching online seems to indicate this option will simply ensure that the Bleed is included with the exported document - so it certainly appears to do the same as 'Include Bleed' when exporting from Affinity

[thomaso]

On 11/29/2023 at 9:29 AM, davide_m said:

padded cover (…)

- Bleed left/right: 9.3 mm

Since the offset appears to be larger than just a rounded millimetre deviation, I wonder whether the "padded" cover could play a role, e.g. in that the print gets applied with insufficient precision. Possibly you can compare with your layout dimensions whether the cover image got printed in 100 % size and whether it overlaps evenly to the cover back (inside) at both outer edges (left and right). The required bleed of total 18.6 mm may be required to get folded at the edges or may indicate a reduced precision for this material. (of course, technically they could mount the printed cover page fully centred).

[davide_m]

17 hours ago, thomaso said:

Since the offset appears to be larger than just a rounded millimetre deviation, I wonder whether the "padded" cover could play a role, e.g. in that the print gets applied with insufficient precision.

Hi @thomaso, thank you for your suggestion! However, I have already printed several Saal Digital Photobooks with padded covers using Saal Digital software to design the photobook: they were all fine with text centred on the spine.

I tried to replicate the issue on Saal Digital without having to actually print the photobook. I uploaded my PDFs with APub units set to millimetres and got a preview of the print from Saal Digital. This is how it looks like, and you can already see that text is not centred even though it is on the APub file:

 

Then, I tried it again with the file that was prepared by @Dan C and unfortunately I got the exact same result.. So, probably the problem is not only due to the rounding error when converting from millimeters to pixels. Later today I will try another test with the official Saal Digital templates for InDesign (opened in APub) to see how it goes and I'll update this post