Strange Font problem

Strange Font problem

[Andreas Schneider]

Hello,

since one of the last betas (I guess two weeks ago), a strange problem 
appears in my current document. The first ~10 page are completely fine (i.e. 
as usual) but the following ~20 pages have some kind of a font problem. The 
font looks bolder/grainy when zooming out in Acrobat and also the scrolling 
is pretty slow. After these pages, it's fine again. I don't see any specific 
trigger, there's nothing "special" on these pages.

Sorry that I can't give any more details, but I wasn't able yet to pinpoint 
the problem. Even producing a long test document using \dorecurse didn't 
provoke that problem.

I made a screenshot of one of the aforementioned spots where it switches - 
in this case from "wrong" to "right".

http://aksdb.homeip.net/ConTeXt_Font.png

I guess you can easily see that the font on the upper page (the wrong one) 
looks different from the page below (the right one). They should be the same 
and it even looks correct when zooming further in. Both pages are 
consecutive and there is no code inbetween (no manual break, nothing).

Has someone seen something like this before and can give me a hint where to 
start looking for the trigger so that I can maybe produce a smaller test 
example to help find and fix the root cause?

Thanks in advance,
Andreas.

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Re: Strange Font problem

[Khaled Hosny]

On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
> Hello,
> 
> since one of the last betas (I guess two weeks ago), a strange problem 
> appears in my current document. The first ~10 page are completely fine (i.e. 
> as usual) but the following ~20 pages have some kind of a font problem. The 
> font looks bolder/grainy when zooming out in Acrobat and also the scrolling 
> is pretty slow. After these pages, it's fine again. I don't see any specific 
> trigger, there's nothing "special" on these pages.

Can you check with other PDF readers, it looks like a reader issue to
me. I've got some strange color issues with ConTeXt generated PDFs and
Adobe's reader in the past, namely any page with images would have the
colors brighter than other pages, since the print was fine (and I don't
use Adobe's for screen reading, I didn't bother). Yours might be
something similar.


-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer
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Re: Strange Font problem

[Aditya Mahajan]

On Wed, 16 Jun 2010, Khaled Hosny wrote:

> On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
>> Hello,
>>
>> since one of the last betas (I guess two weeks ago), a strange problem
>> appears in my current document. The first ~10 page are completely fine (i.e.
>> as usual) but the following ~20 pages have some kind of a font problem. The
>> font looks bolder/grainy when zooming out in Acrobat and also the scrolling
>> is pretty slow. After these pages, it's fine again. I don't see any specific
>> trigger, there's nothing "special" on these pages.
>
> Can you check with other PDF readers, it looks like a reader issue to
> me. I've got some strange color issues with ConTeXt generated PDFs and
> Adobe's reader in the past, namely any page with images would have the
> colors brighter than other pages, since the print was fine (and I don't
> use Adobe's for screen reading, I didn't bother). Yours might be
> something similar.

FWIW, I have noticed similar problems with Adobe reader on linux. Pages 
that contained a png image with transparency appeared duller than other 
pages. But evince and xpdf display the result correctly.

I don't know if the font effects are related or not.

Aditya

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Re: Strange Font problem

[Taco Hoekwater]

Aditya Mahajan wrote:
> On Wed, 16 Jun 2010, Khaled Hosny wrote:
> 
>> On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
>>> Hello,
>>>
>>> since one of the last betas (I guess two weeks ago), a strange problem
>>> appears in my current document. The first ~10 page are completely 
>>> fine (i.e.
>>> as usual) but the following ~20 pages have some kind of a font 
>>> problem. The
>>> font looks bolder/grainy when zooming out in Acrobat and also the 
>>> scrolling
>>> is pretty slow. After these pages, it's fine again. I don't see any 
>>> specific
>>> trigger, there's nothing "special" on these pages.
>>
>> Can you check with other PDF readers, it looks like a reader issue to
>> me. I've got some strange color issues with ConTeXt generated PDFs and
>> Adobe's reader in the past, namely any page with images would have the
>> colors brighter than other pages, since the print was fine (and I don't
>> use Adobe's for screen reading, I didn't bother). Yours might be
>> something similar.
> 
> FWIW, I have noticed similar problems with Adobe reader on linux. Pages 
> that contained a png image with transparency appeared duller than other 
> pages. But evince and xpdf display the result correctly.

This happens because on pages with transparency AR switches to a
different color model, and the resulting color conversions are not
producing the same results as conversion to the default (sRGB, I guess)
color model. It is annoying but unlikely to get fixed as this problem
has been around for ages, and more importantly: Adobe is not convinced
this is an actual bug.

It could be the same problem Andreas reported, but it is hard to say
for sure without looking at Andreas' actual PDF.

Best wishes,
Taco

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Re: Strange Font problem

[Hans Hagen]

On 16-6-2010 3:19, Khaled Hosny wrote:
> On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
>> Hello,
>>
>> since one of the last betas (I guess two weeks ago), a strange problem
>> appears in my current document. The first ~10 page are completely fine (i.e.
>> as usual) but the following ~20 pages have some kind of a font problem. The
>> font looks bolder/grainy when zooming out in Acrobat and also the scrolling
>> is pretty slow. After these pages, it's fine again. I don't see any specific
>> trigger, there's nothing "special" on these pages.
>
> Can you check with other PDF readers, it looks like a reader issue to
> me. I've got some strange color issues with ConTeXt generated PDFs and
> Adobe's reader in the past, namely any page with images would have the
> colors brighter than other pages, since the print was fine (and I don't
> use Adobe's for screen reading, I didn't bother). Yours might be
> something similar.

see taco's answer ... what i normally do then is put some invisible 
transparent color on the first page of the document as this will trigger 
the other color machinery in acrobat

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Re: Strange Font problem

[Andreas Schneider]

Khaled Hosny wrote:

> On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
> 
> Can you check with other PDF readers, it looks like a reader issue to
> me. I've got some strange color issues with ConTeXt generated PDFs and
> Adobe's reader in the past, namely any page with images would have the
> colors brighter than other pages, since the print was fine (and I don't
> use Adobe's for screen reading, I didn't bother). Yours might be
> something similar.

Indeed, it works with XPDF, Okular and Foxit Reader (haven't tried others 
yet). That may explain, why I didn't notice the problem earlier. As it 
seems, it even happens with older context versions (I now tried 2010.05.13 
on a different system) and with older versions of my document of which I was 
pretty sure that they looked fine before - apparently I didn't try with 
Acrobat or just didn't notice the problem back then.

Thanks for that hint in the right direction!

Best Regards,
Andreas.

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Re: Strange Font problem

[Andreas Schneider]

Taco Hoekwater wrote:

> This happens because on pages with transparency AR switches to a
> different color model, and the resulting color conversions are not
> producing the same results as conversion to the default (sRGB, I guess)
> color model. It is annoying but unlikely to get fixed as this problem
> has been around for ages, and more importantly: Adobe is not convinced
> this is an actual bug.
> 
> It could be the same problem Andreas reported, but it is hard to say
> for sure without looking at Andreas' actual PDF.
> 
> Best wishes,
> Taco

It seems indeed to be a problem with Acrobat, and not (directly) ConTeXt. As 
I also wrote in my answer to Khaled, it could be even reproduced on a 
different system with an older ConTeXt version.

Of course that doesn't rule out the possibility, that it's triggered by 
something ConTeXt does. Since it is my diploma thesis I'm working on, I 
can't just publish the PDF without consent from my university (which they 
probably won't give at that point). If you are interested in taking a closer 
look at that problem, I could send you the PDF in private. If you aren't (or 
simply don't have the time), it's also no problem ... as long as the print 
version looks fine, which apparently is the case.

Thank you for your insight :-)
Andreas.

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Re: Strange Font problem

[Khaled Hosny]

On Wed, Jun 16, 2010 at 10:09:11AM +0200, Hans Hagen wrote:
> On 16-6-2010 3:19, Khaled Hosny wrote:
> >On Wed, Jun 16, 2010 at 02:32:48AM +0200, Andreas Schneider wrote:
> >>Hello,
> >>
> >>since one of the last betas (I guess two weeks ago), a strange problem
> >>appears in my current document. The first ~10 page are completely fine (i.e.
> >>as usual) but the following ~20 pages have some kind of a font problem. The
> >>font looks bolder/grainy when zooming out in Acrobat and also the scrolling
> >>is pretty slow. After these pages, it's fine again. I don't see any specific
> >>trigger, there's nothing "special" on these pages.
> >
> >Can you check with other PDF readers, it looks like a reader issue to
> >me. I've got some strange color issues with ConTeXt generated PDFs and
> >Adobe's reader in the past, namely any page with images would have the
> >colors brighter than other pages, since the print was fine (and I don't
> >use Adobe's for screen reading, I didn't bother). Yours might be
> >something similar.
> 
> see taco's answer ... what i normally do then is put some invisible
> transparent color on the first page of the document as this will
> trigger the other color machinery in acrobat

Interesting, I've to try this once I'm back working on next edition of
that book(let).

-- 
 Khaled Hosny
 Arabic localiser and member of Arabeyes.org team
 Free font developer
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