Description:
SVG images in ODF would have an extra copy of PNG format, which makes the file size become large. Is it intentional? If yes, why?

Opening files with SVG images inside or SVM starview metafile in LibreOffice and saving as ODF format files, the file sizes became much more. Then the user found that under the Pictures folder of ODF format files, all the SVG and SVM files had a copy of PNG format, which made the file size became much more than the original file.

The SVG files were made by Apache OpenOffice, In AOO it wouldn't have a PNG copy, But SVM files.

Is this behavior intentional? Would anyone please tell us what it is for? Besides, is there any expert options to control this behavior, i.e., to control if a PNG copy is made or not?

If png version is included to help consumers, which are not able to read svg-images. For example Word got only recently the ability to read svg-images. Including different representations of the same content is explicitly allowed in file format for this purpose.

But now the SVG was general standard, many programs can open or view it, So give up those PNG copy and restore ODT size, maybe it is a good idea, Moreover, SVM files were not have PNG copy, when convert ODF format files include svm files, svm files were be converted to emf files.

Steps to Reproduce:
1.Create an document, odt,ods,odp or odg
2.past vector illustration file as GDI metafile.
3.Save ODF format file
4.Open ODF format file with 7-zip, the pictures folder will have PNG copy files.

Actual Results:  
Every SVG or SVM files in ODF format had an PNG copy, It will increase ODF format file sizes, If have many ODF format files that include a lot of SVG or SVM, Will need many storage space, for government, Large Mechanism and company, It is not a good situation.

Expected Results:
Wish create an option to disable SVG or SVM files in ODF(odt,ods,odp,odg) wont copy of PNG format.
So can reduce LibreOffice ODF format files sizes.


Reproducible: Always


User Profile Reset: Yes



Additional Info:
[Information automatically included from LibreOffice]
Locale: zh-TW
Module: StartModule
[Information guessed from browser]
OS: Windows (All)
OS is 64bit: no


User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:54.0) Gecko/20100101 Firefox/54.0