Export size discrepancy- 0.1mm added

[Kerryfine]

On Affinity V2 I am having trouble exporting my file to pdf and retaining the same document size (which is evident on re-importing the file). 0.1mm is added to the X dimension on export and when I reimport the pdf file there is a thin white margin and the document size is changed from 62 x 117mm to 62.1 x 117mm. Even if I resize again to 62 x 117 and export the file returns as 62.1. The image appears to fit within the document constraints.

 

I had this issue previously on another file I was working with and don’t remember how I finally resolve it after a lot of headache.

 

Edited March 8, 2024 by Kerryfine
Removing files

[walt.farrell]

Here's why it's happening:

1. You have a document that starts out as 62 mm wide, and 300 DPI.
   
   62 mm is 2.4409448818897637795275590551181 inches, and at 300 DPI that is 732.28346456692913385826771653543 pixels.
   
   Or, another way of looking at it: The conversion factor between DPI and DPmm is 0.03937007874015748031496062992126, so 300 DPI is 11.811023622047244094488188976378 pixels per mm, and again, 62 mm gives 732.28346456692913385826771653543 pixels.
    
2. Of course, you can't have .28... pixels in a physical object, so the object must end up 733 pixels to hold all the data. At that point, 733/11.811023622047244094488188976378 gives you 62.060666666666666666666666666666 mm, and rounding up gives you 62.1 mm.

I can't tell you the best way of handling it, though. Sorry.

[loukash]

1 hour ago, Kerryfine said:

0.1mm is added to the X dimension on export

Given that alone the crop marks in a PDF intended for print are already 0.25 pt = 0.08 mm thick, a ±0.1 mm size difference is absolutely negligible.

But for the fun of it, I have launched Illustrator CS5 on my "antique" MacBook Pro to see what happens if I save a 67×117 mm @ 300 dpi as a standard PDF.
After all, Adobe should have gotten it right, right?
Guess what the size of the PDF is?
That's right: 62.1 × 117 mm

That's how PDF is supposed to work. It's by design.

[loukash]

1 hour ago, walt.farrell said:

the best way of handling it

The math is simple, and you want an integer size in pixels.

62 mm = 2.440945 in = 732.283465 px @ 300 dpi

732 px ÷ 2.440945 in = 299.883856457 dpi
or
733 px ÷ 2.440945 in = 300.293533857 dpi

Affinity 2 supports non-integer DPI values. (Which, I think, is new: I vaguely remember there were some issues in v1.)

The tricky part will be to match both the width and the height if both are meant to be integer mm because mm and px rarely overlap in integer values, if at all.
So here you can hardly have the cake and eat it, too…

[Kerryfine]

Appreciate the input but for the place I submit this design, they require the image to be the exact size. There still should be a way to crop this image and export it as exactly the size the document states it is.

And when I had this issue previously with another document with image size 117x185mm I somehow resolved it after MANY attempts exporting and reimporting (not sure the specific details). There must be a way to get around this.

Edited March 7, 2024 by Kerryfine

[Kerryfine]

Also, when I import the file into Linearity Curve vector program, then export pdf and open in AD, the file remains the correct size, however the COLORS change slightly so I have to correct them back in AD before exporting again leading to the same size issue…

[Kerryfine]

Well, I just resized the document in AD to 61.9mm x 117mm, exported to PDF and what do you know… importing it back in I got 62mm x 117mm. Yes there is a microscopic sliver of blank space on the right side (of 0.1mm) but won’t be noticeable on printing and the company will accept the file as it’s now the correct size… this must be a program issue that should be corrected. I remember trying this same method yesterday and it DIDN’T work…

[Oufti]

43 minutes ago, Kerryfine said:

Well, I just resized the document in AD to 61.9mm x 117mm, exported to PDF and what do you know… importing it back in I got 62mm x 117mm. Yes there is a microscopic sliver of blank space on the right side

Next time, you can go in the Document setup panel, change the measurement unit to 'pixels', modify the document size by removing any decimal pixels and finally change back to the unit you prefer.

Your document will be a very little bit smaller, so it'll fit in automatic control procedures, but you won't have any white line on the sides.  

[Kerryfine]

3 hours ago, Oufti said:

Next time, you can go in the Document setup panel, change the measurement unit to 'pixels', modify the document size by removing any decimal pixels and finally change back to the unit you prefer.

Your document will be a very little bit smaller, so it'll fit in automatic control procedures, but you won't have any white line on the sides.  

THIS SOLVED MY PROBLEM COMPLETELY. Thank you, perfect outcome.

For any future people who suffer from this problem:

Resize - convert to pixels - remove decimal points on whatever dimension is exporting 0.1 larger - apply - resize - change back to mm - export

[loukash]

As a side note: I felt like having a déjà vu in this thread, and now I know why.
Here in this old thread I've explained it in more details already:

ff. 

[Zaxonov]

On 3/8/2024 at 12:56 PM, loukash said:

As a side note: I felt like having a déjà vu in this thread, and now I know why.
Here in this old thread I've explained it in more details already:

ff. 

Is it an issue for any app that exports to PDF because of the PDF format properties or is it because Affinity always convert to pixels somehow? That drives me nuts...

[Alfred]

2 minutes ago, Zaxonov said:

DOUBLE POST SORRY

Click on the ellipsis (‘…’) at the top right-hand corner of your post to display a menu which should include a ‘Hide’ option.

[Zaxonov]

2 minutes ago, Alfred said:

Click on the ellipsis (‘…’) at the top right-hand corner of your post to display a menu which should include a ‘Hide’ option.

Thanks. I thought that was a feature that hides posts only for myself and not the other forum members. 

[Alfred]

5 minutes ago, Zaxonov said:

Thanks. I thought that was a feature that hides posts only for myself and not the other forum members. 

No, it hides posts from everyone except the moderators. If I go to my quote of your post and click on the arrow to try to view it, I get this:

Quote

Sorry!

We could not locate the item you are trying to view.

 

[loukash]

1 hour ago, Zaxonov said:

Is it an issue for any app that exports to PDF because of the PDF format properties

As far as my experience goes: yes.

[Zaxonov]

18 minutes ago, loukash said:

As far as my experience goes: yes.

Alright thanks. I suppose it's because of the unit of PDF being dots and resolution being in dpi... not metric.