Converting the attached PDF with the latest GroupDocs.Viewer to HTML or PNG produces some strange artifacts (see screenshot)
image.png (61.8 KB)
It’s most noticeable for PNG.
The problem here, is how small dots are combined when “zooming out” / lowering the resolution.
When printed, it would look like a gray background (in the original).
So ideally, this would also work in GroupDocs, that multiple small dots, will appear gray?
PDF dots are too big.zip (223.7 KB)
I have reproduced this issue. Can you please confirm that your application is targeting .NET Framework?
To improve rendering to HTML you can use enable WrapImagesInSvg. See output in WrapImagesInSvg.zip (291.7 KB)
HtmlViewOptions viewOptions = HtmlViewOptions.ForEmbeddedResources();
viewOptions.PdfOptions.WrapImagesInSvg = true;
When rendering to PNG you can also try enabling RenderOriginalPageSize and get better output quality but dots are disappearing in this case see RenderOriginalPageSize.png (26.4 KB)
PngViewOptions viewOptions = new PngViewOptions();
viewOptions.PdfOptions.RenderOriginalPageSize = true;
In case of rendering to PNG we’ll investigate this issue and update you when it will be fixed.
Issue ID for reference i VIEWERNET-4826.
Yes we’re using .NET Framework still.
Thanks a lot for the suggested fix, I can confirm that this greatly improves both outputs.
The HTML output is pretty much spot-on. 
Do you know if this has any performance implications, as it “wraps images in to SVG” now?
Same question for Rending in original page size?
There are no noticeable performance implications to render with WrapImagesInSvg
| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated |
|---|---|---|---|---|---|---|
| WrapImagesInSvgFalse | 532.8 ms | 259.0 ms | 14.20 ms | 11000.0000 | 1000.0000 | 70.79 MB |
| WrapImagesInSvgTrue | 526.8 ms | 909.5 ms | 49.85 ms | 11000.0000 | 1000.0000 | 72.05 MB |
RenderOriginalPageSize was a bit faster:
| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated |
|---|---|---|---|---|---|---|---|
| DefaultRendering | 122.40 ms | 48.70 ms | 2.670 ms | 3000.0000 | 1000.0000 | 500.0000 | 18.59 MB |
| WrapImagesInSvg | 83.82 ms | 25.43 ms | 1.394 ms | 2857.1429 | 1000.0000 | 285.7143 | 18.16 MB |
I was testing the attached file but the results may differ for files with different content.
