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Posted to dev@pdfbox.apache.org by Daniel Wilson <wi...@gmail.com> on 2010/02/26 22:43:44 UTC
Do we have any examples of trying to *use* or *evaluate* a
PDFunction?
The gradients I'm trying to implement for PDFBOX-615 are defined in part by
functions.
We are parsing the functions and instantiating derivatives of PDFunction ...
but I can't find anything that evaluates the function. e.g. if I pass the
function 2, what does it return?
A quick grep didn't find any such examples ... in fact the only classes that
contain an instance of PDFunction are PDDeviceN and PDSeparation, both of
which return an empty function rather than returning the one that the class
was loaded with.
Is this a known gap in our support of functions? Does someone know where,
in fact, we do use them? Or is this one of those things, no one's really
sure about?
Thanks!
Daniel
Re: Do we have any examples of trying to *use* or *evaluate* a PDFunction?
Posted by Andreas Lehmkuehler <an...@lehmi.de>.
Hi,
Daniel Wilson schrieb:
> Thanks, Andreas.
>
> The spec in that area is certainly not easy to follow, but I _think_ I have
> types 2 & 3 implemented. And perhaps I can/should revisit the tintTransform
> functionality ...
That would be great, especially type 2 functions are used from time to time
within the PDSeparation colorspace.
BR
Andreas Lehmkühler
> Daniel
>
> On Sat, Feb 27, 2010 at 6:31 AM, Andreas Lehmkuehler <an...@lehmi.de>wrote:
>
>> Hi,
>>
>> Daniel Wilson schrieb:
>>
>> The gradients I'm trying to implement for PDFBOX-615 are defined in part
>>> by
>>> functions.
>>>
>>> We are parsing the functions and instantiating derivatives of PDFunction
>>> ...
>>> but I can't find anything that evaluates the function. e.g. if I pass the
>>> function 2, what does it return?
>>>
>>> A quick grep didn't find any such examples ... in fact the only classes
>>> that
>>> contain an instance of PDFunction are PDDeviceN and PDSeparation, both of
>>> which return an empty function rather than returning the one that the
>>> class
>>> was loaded with.
>>>
>>> Is this a known gap in our support of functions? Does someone know where,
>>> in fact, we do use them? Or is this one of those things, no one's really
>>> sure about?
>>>
>> That is a known gap. Have a look at [1]. I thought that I understood how
>> these
>> functions work, but when I tried to implement e.g FunctionType2 I'd
>> realized
>> that I didn't. Obviously it is a little bit more tricky than I expected or
>> probably it is just my limited ability to understand complex english texts.
>>
>> Thanks!
>>> Daniel
>>>
>>>
>> BR
>> Andreas Lehmkühler
>>
>> [1] https://issues.apache.org/jira/browse/PDFBOX-519
>>
>
Re: Do we have any examples of trying to *use* or *evaluate* a
PDFunction?
Posted by Daniel Wilson <wi...@gmail.com>.
Thanks, Andreas.
The spec in that area is certainly not easy to follow, but I _think_ I have
types 2 & 3 implemented. And perhaps I can/should revisit the tintTransform
functionality ...
Daniel
On Sat, Feb 27, 2010 at 6:31 AM, Andreas Lehmkuehler <an...@lehmi.de>wrote:
> Hi,
>
> Daniel Wilson schrieb:
>
> The gradients I'm trying to implement for PDFBOX-615 are defined in part
>> by
>> functions.
>>
>> We are parsing the functions and instantiating derivatives of PDFunction
>> ...
>> but I can't find anything that evaluates the function. e.g. if I pass the
>> function 2, what does it return?
>>
>> A quick grep didn't find any such examples ... in fact the only classes
>> that
>> contain an instance of PDFunction are PDDeviceN and PDSeparation, both of
>> which return an empty function rather than returning the one that the
>> class
>> was loaded with.
>>
>> Is this a known gap in our support of functions? Does someone know where,
>> in fact, we do use them? Or is this one of those things, no one's really
>> sure about?
>>
> That is a known gap. Have a look at [1]. I thought that I understood how
> these
> functions work, but when I tried to implement e.g FunctionType2 I'd
> realized
> that I didn't. Obviously it is a little bit more tricky than I expected or
> probably it is just my limited ability to understand complex english texts.
>
> Thanks!
>>
>> Daniel
>>
>>
> BR
> Andreas Lehmkühler
>
> [1] https://issues.apache.org/jira/browse/PDFBOX-519
>
Re: Do we have any examples of trying to *use* or *evaluate* a PDFunction?
Posted by Andreas Lehmkuehler <an...@lehmi.de>.
Hi,
Daniel Wilson schrieb:
> The gradients I'm trying to implement for PDFBOX-615 are defined in part by
> functions.
>
> We are parsing the functions and instantiating derivatives of PDFunction ...
> but I can't find anything that evaluates the function. e.g. if I pass the
> function 2, what does it return?
>
> A quick grep didn't find any such examples ... in fact the only classes that
> contain an instance of PDFunction are PDDeviceN and PDSeparation, both of
> which return an empty function rather than returning the one that the class
> was loaded with.
>
> Is this a known gap in our support of functions? Does someone know where,
> in fact, we do use them? Or is this one of those things, no one's really
> sure about?
That is a known gap. Have a look at [1]. I thought that I understood how these
functions work, but when I tried to implement e.g FunctionType2 I'd realized
that I didn't. Obviously it is a little bit more tricky than I expected or
probably it is just my limited ability to understand complex english texts.
> Thanks!
>
> Daniel
>
BR
Andreas Lehmkühler
[1] https://issues.apache.org/jira/browse/PDFBOX-519