866574 - Pdf.js rasters the document in too low resolution and with antialiasing when printing

Status: RESOLVED DUPLICATE of bug 1269023

(Firefox :: PDF Viewer, defect, P3)

Description

[Konstantin]

Attachment: Sample 1: Print-Scans (view with external PDF reader for correct rendering!). Compare - Page 1: printed with pdf.js (poor quality) vs. Page 2: printed with external pdf reader (Evince; original quality).

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:20.0) Gecko/20100101 Firefox/20.0
Build ID: 20130329030832

Steps to reproduce:

I printed a black&white text only pdf document
specifically it was http://math.stanford.edu/~dlitt/briefnotes/notes/ClosedLie.pdf


Actual results:

The printed output shows dithering artefacts.

My interpretation is that pdf.js renders the document in a lower resolution than the printer's resolution. In addition pdf.js applies antialiasing techniques which result in pixels being rasterised not only in black&white but gray scale as well.
While this looks good on screen, the printer then starts to dither the gray scale and the document looks ugly.

I also did a print-to-file with pdf.js and I could very well see the gray scale pixels that were produced in the resulting document. (I opened the print-to-file-output document in another pdf viewer and enlarged it)


Expected results:

Pdf.js should have rendered the document in the printer's resolution and using black&white pixels only. This would have created a sharp and good looking document.

Indeed another pdf reader I used (Evince) produced exactly that.

I attached a file with scans of the two prints.
Page 1: A scan of the rasterised output by pdf.js
Page 2: A scan of the good output another pdf reader created.

Comment 1

[Thomas D. (:thomas8)]

Comment on attachment 742911 [details]
Sample 1: Print-Scans (view with external PDF reader for correct rendering!). Compare - Page 1: printed with pdf.js (poor quality) vs. Page 2: printed with external pdf reader (Evince; original quality).

No irony intended, but you actually have to open Sample 1 with an *external* PDF reader (not FF-pdfjs) to view the document correctly and see the difference in quality between pdfjs printout (bad) and external pdf reader printout (good)...

Comment 2

[Konstantin]

Comment on attachment 742911 [details]
Sample 1: Print-Scans (view with external PDF reader for correct rendering!). Compare - Page 1: printed with pdf.js (poor quality) vs. Page 2: printed with external pdf reader (Evince; original quality).

Actually 400% zoom makes the issue visible pretty well in in pdf.js, too.
(at least on my machine...)

Comment 3

[Joel Kleppinger]

Text and table elements should not be rasterized by pdf.js when printing (noticeable when printing to PDF via PDFCreator).  It should print as text and tables with the appropriate style in PDF.  That's where the majority of the poor print quality comes from.

Comment 4

[Gervase Markham [:gerv]]

This actually creates problems beyond the cosmetic. Last time I travelled by Eurostar I printed my tickets (which were given as a PDF) and the gates couldn't read the QR code. This time, I've printed them using evince.

Is anyone currently working on pdf.js?

Gerv

Comment 5

[Gervase Markham [:gerv]]

CCing Vivien - are you working on pdf.js at the moment? If not, who is?

Gerv

Comment 6

[Gervase Markham [:gerv]]

NEEDINFO vivian.

Gerv

Comment 7

[Vivien Nicolas (:vingtetun) (:21) - (NOT reading bugmails, needinfo? please)]

I'm not actively working on pdf.js anymore. Redirecting the needinfo to Yury :)

Comment 8

[Yury Delendik (:yury)]

Bug 745025 addressed this for Mac OSX. Bug 811002 addresses this for Windows. So resolution of this particular bug directly depends on resolution of bug 932289 (at Core->Graphics) -- pdf.js relies on the platform's mozPrintCallback to not rasterize the output.