Hi. I discovered some thing I did not hear before ! An open source free of charge secure reduction library for PDF ! The secure reduction is highly wanted feature, but unfortunately not available for Linux as free source. Only in recent versions of Ghost script this feature implemented BUT FOR VERY LIMITED SCOPE .... Just several hrs ago, I discover free of charge & open source library for secure reduction of PDF: https://itextpdf.com/en https://itextpdf.com/en/products/itext-7/pdfsweep & here bellow it's repository on Gitlab: for java: https://itextpdf.com/en/products/itext-7/pdfsweep for .NET (C#): https://github.com/itext/i7n-pdfsweep It is the only open source EFFICIENT library. See it, you may take benefit from it in feature to create "secure eraser" by which user can erase contents of PDF securely without raster the PDF with subsequent change of text-based PDF into scanned-like PDF & loss of search & OCR property of original PDF .....
Okular is not a pdf editor
@Albert Astals Cid Dear Albert ! I know that Okular is not a PDF editor ! But this should not bear any thing on this issue due to the following facts: 1) 1st point (& most importantly) you are already implement this feature - but in very bad way depending on Ghost script - so why not enhancing ALREADY IMPLEMENTED feature ?? Please see this closed issue: https://bugs.kde.org/show_bug.cgi?id=377456 You are, currently, using "Force rasterization" technique to achieve this as following: "File -> Print (Ctrl+P)", choose PDF printer, go to "Options -> PDF options", and check the "Force rasterization" So, you are already implement this EDIT feature ... ! However, it is very bad because the following: a. it lead to very huge size of output PDF, b. lead to convert text based PDF into scanned like PDF, c. lead to loss OCR feature in output PDF. So, I would like to asking you, friendly, what is the contra-indication to enhance & improve ALREADY IMPLEMENTED feature ? With new library that I discovered: a. no huge increase in size of output PDF file, b. resolution not effected badly, c. text based PDF will remain text based PDF, d. scanned PDF will remain scanned PDF, e. no loss of OCR in output PDF, f. the process will be more simple from the current one: you can achieve this just by creating "eraser" to achieve secure erasing in Non-representational mode .... From my side, I'm ready to support you by money (donation) if you need money support to add this useful feature for almost all PDF users. 2) currently, Okular is the only tool on Linux which is most suitable on to apply this feature because this feature NEED a VIEWER to achieve it, & Okular is the best from this point of view .....
Okular itself does not handle PDF documents, it uses so called Generators for that. The PDF generator uses poppler as PDF library. So implementing your suggested feature would mean that the Generator interface needs to be expanded, and the PDF generator has to use two PDF libraries, which communicate via PDF. So from a technical point of view, Okular is not well prepared for adding various PDF manipulation features, including this one. In the other bug you called reduction a hidden feature. I agree that it is a hidden feature from a user point of view, but it is hidden because: - It is not intended to be a feature - Okular developers don’t feel the need to make such a feature available - It performs very bad Options to promote this feature don’t seem good to me: - The current “implementation” is very bad - Adding a good implementation would be disproportionately complex, due to there reasons mentioned above - Okular developers feel that this feature doesn’t really fit Okular’s scope. I am closing this bug now. Reopen if you can show that my arguments don’t hold.