[XeTeX] graphic special effects question

Ross Moore ross at ics.mq.edu.au
Sat Feb 13 00:53:27 CET 2010

Hi Alan,

On 13/02/2010, at 6:28 AM, Alan Hoenig wrote:

> I hope to be able to produce the following graphic effect from  
> within XeTeX.  If I include a photo (say) within a TeX document,  
> I'd like to be able to superpose a smaller square 'filter' over a  
> portion of it so that the original pic shows through, but appears  
> lighter (or perhaps darker).  That is, all the features of the  
> original are present and visible but filtered by the overlay to  
> appear darker or lighter than the surrounding portion of the  
> photo.  How can I do this?  If there is no XeTeX solution, what is  
> the best way to proceed.  Thanks for any info!

This sound like it just a question of the "opacity" of the overlay,
to be somewhat less than 100%.

So if you use some other PDF tool to create an opaque square
to be your filter, you would simply position it over the main
image, using \includegraphics  and TeX's boxes, in the usual way.

Certainly Adobe's Illustrator can create the opaque image,
but so should many other graphics tools.
You could even do it with Mathematica v6+ .

I don't see this as being a XeTeX thing, but a PDF rendering thing.
It should be the same with pdfTeX or LuaTeX, and only depend upon
whether the PDF browser supports transparency/opacity.

> ---Alan Hoenig

Hope this helps,


Ross Moore                                       ross at maths.mq.edu.au
Mathematics Department                           office: E7A-419
Macquarie University                             tel: +61 (0)2 9850 8955
Sydney, Australia  2109                          fax: +61 (0)2 9850 8114

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