Bug 133881 - Kerning changed in exported PDF. Kerning in ODT looks smooth. Kerning in PDF chaotic
Summary: Kerning changed in exported PDF. Kerning in ODT looks smooth. Kerning in PDF ...
Status: NEW
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Printing and PDF export (show other bugs)
Version:
(earliest affected)
6.4.4.2 release
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: Kerning
  Show dependency treegraph
 
Reported: 2020-06-10 21:49 UTC by thatho
Modified: 2023-10-21 12:31 UTC (History)
6 users (show)

See Also:
Crash report or crash signature:


Attachments
GIF of two PNGs (ODT and PDF) (39.95 KB, image/gif)
2020-06-10 21:52 UTC, thatho
Details
2020-06-10 spacing before hyphen is null in ODT (11.36 KB, image/png)
2020-06-10 21:52 UTC, thatho
Details
The two original screenshots used to create the gif (26.37 KB, image/png)
2020-06-10 21:53 UTC, thatho
Details
The original ODT (24.69 KB, application/vnd.oasis.opendocument.text)
2020-06-12 11:55 UTC, thatho
Details
The PDF export (24.02 KB, application/pdf)
2020-06-12 11:55 UTC, thatho
Details
A PNG export of the ODT (3.10 MB, image/png)
2020-06-12 11:56 UTC, thatho
Details
A screenshot of the PNG and PDF side by side. (181.18 KB, image/png)
2020-06-12 11:56 UTC, thatho
Details
Highlight of the differences using vector objects (182.53 KB, image/png)
2020-06-12 11:57 UTC, thatho
Details
The vector source to "Highlight of the differences" (3.39 KB, image/svg+xml)
2020-06-12 11:58 UTC, thatho
Details
2020-06-12 kerning issue LO PDF export vs CutePDF Writer print (298.58 KB, image/jpeg)
2022-02-14 09:46 UTC, thatho
Details
2020-06-12 kerning issue LO PDF export vs CutePDF Writer print new (295.32 KB, image/jpeg)
2022-02-14 09:48 UTC, thatho
Details

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Description thatho 2020-06-10 21:49:59 UTC
Description:
Export to PDF is not WYSIWYG. The kerning changed in exported PDF. Kerning in ODT looks smooth and valid. Kerning in PDF is chaotic.

Kerning if ODT looks good, because: the spaces between letters and hyphens are minimal. Not such in the PDF.

Steps to Reproduce:
1. Create any text.
2. Export to PDF
3. Observe difference in kerning

Actual Results:
The text remains almost WYSIWYG.

Expected Results:
There are large disproportionalities in kerning and letter position between the ODT and PDF.


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 7.1.0.0.alpha0+ (x64)
Build ID: 4c4b3218b8595a9809ffade0cfd064f3d9335dff
CPU threads: 8; OS: Windows 10.0 Build 18362; UI render: Skia/Raster; VCL: win
Locale: cs-CZ (cs_CZ); UI: en-US
Calc: CL

Also in LO 6.4.4
Comment 1 thatho 2020-06-10 21:52:11 UTC
Created attachment 161863 [details]
GIF of two PNGs (ODT and PDF)

Differences in kerning can be spotted around the hyphens. The length of the hyphens differ. The spacing before the hyphen differ. Some kerning is awfully wrong in PDF. I consider the ODT neat and nice and correct. The PDF export is messy.
Comment 2 thatho 2020-06-10 21:52:40 UTC
Created attachment 161864 [details]
2020-06-10 spacing before hyphen is null in ODT
Comment 3 thatho 2020-06-10 21:53:39 UTC
Created attachment 161865 [details]
The two original screenshots used to create the gif
Comment 4 Telesto 2020-06-11 14:36:43 UTC
Please add an test ODT file and the exported PDF.. would make the bug report more complete.
Comment 5 thatho 2020-06-12 11:55:29 UTC
Created attachment 161914 [details]
The original ODT
Comment 6 thatho 2020-06-12 11:55:49 UTC
Created attachment 161915 [details]
The PDF export
Comment 7 thatho 2020-06-12 11:56:17 UTC
Created attachment 161916 [details]
A PNG export of the ODT

ODT cannot be enlarged more than 600%. A larger zoom was needed. No kerning or aligning differences has been observed to the ODT.
Comment 8 thatho 2020-06-12 11:56:44 UTC
Created attachment 161917 [details]
A screenshot of the PNG and PDF side by side.
Comment 9 thatho 2020-06-12 11:57:18 UTC
Created attachment 161918 [details]
Highlight of the differences using vector objects

Some vector elements were placed into the previous image to highlight the differences. The vector elements of same color are identical, they are clones. Namely the differences:
* different vertical alignment of the "y", "á" and "z".
* different horizontal spacing (kerning) between "s" and "z"
Comment 10 thatho 2020-06-12 11:58:02 UTC
Created attachment 161919 [details]
The vector source to "Highlight of the differences"

Highlight of the differences in vector (Inkscape has been used)
Comment 11 thatho 2020-06-12 11:58:59 UTC
The following has been added to the bug report:

The original ODT
2020-06-12 kerning issue.odt

The PDF export
2020-06-12 kerning issue.pdf

A PNG export of the ODT: ODT cannot be enlarged more than 600%. A larger zoom was needed. No kerning or aligning differences has been observed to the ODT.
2020-06-12 kerning issue.png

A screenshot of the PNG and PDF side by side.
2020-06-12 kerning issue (compare ODT_PNG and PDF).png

Highlight of the differences:
2020-06-12 kerning issue (compare ODT_PNG and PDF) diff in aligning and kerning.png
Some vector elements were placed into the previous image to highlight the differences. The vector elements of same color are identical, they are clones. Namely the differences:
* different vertical alignment of the "y", "á" and "z".
* different horizontal spacing (kerning) between "s" and "z"

Highlight of the differences in vector (Inkscape has been used):
2020-06-12 kerning issue (compare ODT_PNG and PDF) diff in aligning and kerning.svg

Version: 7.1.0.0.alpha0+ (x64)
Build ID: a201ab6f47c2d5a7ba4c5f998b0aa231cae82010
CPU threads: 8; OS: Windows 10.0 Build 18362; UI render: Skia/Raster; VCL: win
Locale: cs-CZ (cs_CZ); UI: en-US
Calc: CL

Also in 6.4.4.2
Comment 12 Telesto 2020-06-12 12:19:32 UTC
The line breaking has changed in 7.0 The situation appears to have improved..
Version: 7.1.0.0.alpha0+ (x64)
Build ID: a201ab6f47c2d5a7ba4c5f998b0aa231cae82010
CPU threads: 4; OS: Windows 6.3 Build 9600; UI render: default; VCL: win
Locale: nl-NL (nl_NL); UI: en-US
Calc: CL

However, not that good in spotting kerning issues
Comment 13 thatho 2020-07-06 21:11:06 UTC
I confirm that the issues is NOT changed in

Version: 7.1.0.0.alpha0+ (x64)
Build ID: 7dc3a20cab712ee987ea25a8f5728529521485b7
CPU threads: 8; OS: Windows 10.0 Build 18362; UI render: Skia/Raster; VCL: win
Locale: cs-CZ (cs_CZ); UI: en-US
Calc: CL

Kerning issue is still present and I did not registered any improvement.
Comment 14 Buovjaga 2021-08-13 12:18:04 UTC
(In reply to thatho from comment #5)
> Created attachment 161914 [details]
> The original ODT

No problem here

Version: 7.1.5.2 (x64) / LibreOffice Community
Build ID: 85f04e9f809797b8199d13c421bd8a2b025d52b5
CPU threads: 2; OS: Windows 10.0 Build 19042; UI render: Skia/Raster; VCL: win
Locale: fi-FI (fi_FI); UI: fi-FI
Calc: threaded
Comment 15 Telesto 2021-08-13 15:29:51 UTC
@thatho
Is the issue still present in a recent version of LibreOffice?

Putting STATUS to NEEDINFO
Comment 16 QA Administrators 2022-02-10 03:41:22 UTC Comment hidden (obsolete)
Comment 17 thatho 2022-02-14 09:01:29 UTC
The same faulty results are received with

Version: 7.4.0.0.alpha0+ (x64) / LibreOffice Community
Build ID: cfe7dc2ef91ea119ea54b56e207ef7a77291a9d7
CPU threads: 8; OS: Windows 10.0 Build 19044; UI render: Skia/Raster; VCL: win
Locale: cs-CZ (cs_CZ); UI: en-US
Calc: CL
Comment 18 thatho 2022-02-14 09:06:16 UTC
The same faulty results are received with

Version: 7.3.0.3 (x64) / LibreOffice Community
Build ID: 0f246aa12d0eee4a0f7adcefbf7c878fc2238db3
CPU threads: 8; OS: Windows 10.0 Build 19044; UI render: Skia/Raster; VCL: win
Locale: cs-CZ (cs_CZ); UI: en-US
Calc: threaded
Comment 19 thatho 2022-02-14 09:42:32 UTC
When printed the PDF using CutePDF Writer, no differences to the original ODT were spotted.

I attached a difference image between the export using LO export tool and printing to CutePDF Writer. There is quite a scheme. God results are achieved at the beginning of the lines. But then mess penetrates to the end of the lines. And the largest differences are at the end of the lines.
Comment 20 thatho 2022-02-14 09:46:04 UTC
Created attachment 178260 [details]
2020-06-12 kerning issue LO PDF export vs CutePDF Writer print

Take to PDFs: a LO export and CutePDF Writer printout.

Export the sheet into PNG using Acrobat Reader

Apply manipulation to receive a difference file https://graphicdesign.stackexchange.com/questions/27484/get-difference-between-two-images-as-transparent-image-in-gimp

Although the two exports to PNGs may not be in scale. There is a visible deviation between the two PDFs. Some beginning of the lines match exactly, even up the the middle of the line (singular symbols excluded), but the ends of line are just a mess. There are huge differences looking "using typography glasses".
Comment 21 thatho 2022-02-14 09:48:19 UTC
Created attachment 178261 [details]
2020-06-12 kerning issue LO PDF export vs CutePDF Writer print new

correction: inverting colours
Comment 22 Telesto 2022-02-14 10:31:05 UTC
Well I'm not really good at this..

But I do find 'szusz' kerning being off.. And I do confirm the kerning not being exactly the same for exported PNG of the document and compared with PDFxchange export.
Comment 23 Telesto 2022-02-14 10:32:29 UTC
And well if you apply highlighting into attachment 161914 [details] you can notice wiggling in Writer (created separate bug for that bug 147406)
Comment 24 Telesto 2022-02-14 14:11:18 UTC
@Caolan
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