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Home / Hats off ! With small request :slight_smile:


First off, as others have stated, hats off for making a truly excellent PDF viewer, SumatraPDF is so much better than everything else out there in the bloatware sphere :slight_smile:

A small feature request, Acrobat Viewer has an option for “Show Transparency Grid”. I’ve tried tinkering with background color settings (in advanced settings) to add alpha transparency (like #00FFFFFF) without much luck… basically what I’m looking for is, if the PDF has a transparent background, the option to show it as a grid instead of as default color white which is the current behavior.

Kudos again. Love this PDF viewer.


In PDF the text is foreground and placed on a RGB canvas background so there is no need for alpha transparency in either.
The canvas colour is not translucent it is opaque just like in the printer, otherwise the desktop would be showing.
Adobe are efectively adding a Greytone Grid over a solid grey background colour.then image transparency can occasionally be seen on that solid background, Most images are opaque and thus that feature is generally only of value to graphic artists which Adobe need to keep happy. When using Acrobat for reviewing documents I would only try it 0.3% of the time ( i.e about once a year) . For a reader app it is an unnecessary interference

With layered images overlapping then there is an esential need for transparency which admittedly MuPDF has problems with getting right, however there is no “editing” of those image values. to let the grid change.appearance.


I think what you’re saying is the underlying library that SumatraPDF is built upon does not support this… if that’s the case I completely get it, not as simple as exposing a config value in the lib.

If you’re saying that this should not be necessary here’s my use case: I have a document (a vector image in a PDF container) on transparent BG that’s outermost element is white and therefore bleeds/blends into the forced white bg. The greyscale makes it possible to see white outer elements.


I dont delve deep into the code (way too complex for me to pick my way through) but my understanding is that it could require significant effort by the one developer to impliment well but only be used by the few

I too work over 8 hours a day with vector files, hence I can also need that function on some occasions, but it is often easier for me to temporarily flip vector colours whilst looking for “invisible” rendering of parts especially when done by others.

It may be worth raising on github using an example file and description of useful / general scenario


Sure - I thought it might be as simple as exposing an existing option in the library … I appreciate you taking the time to investigate it, and again kudos on a job well done this is still my fav PDF viewer :slight_smile: [that’s why I want this 1 feature, it’s like finding the piece of software that’s 99% perfect] :slight_smile: