On 04/06/2010, at 11:59 PM, Manuel Pégourié-Gonnard wrote:

> This explains the difference in the output format. Unfortunately, I'm not sure
> how to reliably handle this.

Easy :) Update my version.
Unfortunately MacPorts is a big pain to use and everything must be compiled 
from scratch.
And ImageMagick uses *a lot* of dependencies.

Hence the delay on this message.

I've now updated the Makefile for the newer version of ImageMagick but the 
numbers are all a hack.
Maybe now it will work?

BTW, the reason that you get "rounding errors" or whatever I was calling them, 
is that the PDFs must first be converted to PNG (with a specific resolution) 
before being compared. Imperceptible changes in glyph placement can affect how 
the image is discretised, and you can end up with a line of pixels, say, (or 
sometimes just a single pixel) that have ended up being generated differently.

There might be some antialiasing effects that're compounding the problem but I 
haven't looked into ImageMagick enough to know if that's the case (and if so, 
how to turn it off).


>>> Or maybe we can combine both modes: ship the .safe.pdf files (I think they 
>>> are
>>> valuable) and allow a (local) regression-testing mode. It should be doable 
>>> by
>>> adjusting the location of the reference files depending on the target.
>> 
>> That's a good idea.
>> 
> But it makes more work for you :-)

Remind me if I forget, but that doesn't seem like toooooo much work.

-- Will


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