Created attachment 57904 [details] PDF with bitmap aliasing and object placement inaccuracies. (Note: I only know how to install Macports version, today 0.18.2; I do not know if this happens in a later version) The following PDF has two problems when rendered with `pdftoppm`: pdftoppm -r 159 -f 27 -l 27 -tiff sample.pdf > output.tiff 1. Either the rendered bitmaps have aliasing problems or the output has some horizontal lines missing. 2. The placement of one bitmap layer (top black ink) with respect to the other one (bottom color) is inaccurate. As a result color seems displaced. See embedded "output(pdftoppm).jpg" pointing out areas where this happens. Rendering with `pdftocairo` provides no bitmap antialias whatsoever (which I would consider a bug too), so it makes it difficult to see whether the two bugs above happen or not too. None of these issues happen when rendering with Acrobat X (i.e. Acrobat renders this PDF flawlessly).
Created attachment 57905 [details] Rendered sample with notes pointing out rendering inaccuracies.
Oops, the correct `pdftoppm` command-line is: pdftoppm -r 159 -tiff sample.pdf > output.tiff
pdftocairo equally has problems with this PDF, albeit showing up differently: no antialias whatsoever is applied to the bitmaps.
Rendering it with actual master, rendered with 150 dpi, is better than the attached rendered sample. But it will never be comparable with output of Acrobat: one of the biggest difference between poppler and acrobat is, that with poppler You render it with a given resolution and then see a bitmap, and when You zoom that bitmap You begin to see pixel. When You zoom with acrobat, it renders it always again considering the zoom factor and viewable section. So pdftoppm will never be a "viewer" in the meaning of interactive zooming. That can only done by a "windows" program using the poppler library!
Created attachment 60639 [details] Rendered sample (with Photoshop; void of artifacts) I think you missed my points. I never talked about zooming: 1) I was pointing in the rendered sample to specific artifacts: there seem to be specific lines causing a staircase effect, and it is **not** a problem of poor antialiasing, as well as poor alignment of layers. 2) Those artifacts do not appear on Acrobat **when rendering at exactly the same resolution**. They appear in pdftoppm's version but not Acrobat's **at exactly the same ppi resolution**. I am aware that zooming in Acrobat would re-render the page at higher ppi, but that is not what I was talking about. Please open the rendered sample and observe the artifacts. Here I attach another rendered sample, at exactly the same resolution (159) rendered with Photoshop 12.1 (CS5.5), which renders similar to Acrobat and do not present those artifacts.
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