[pdftex] bug with included transparent graphics

[James Quirk]

On Mon, 31 Dec 2007, Victor Ivrii wrote:
> 
> On Mac OSX 10.4.11, pdftex-1.40.3 neither AR 8.1.1 nor AR 7.0.9 nor 3
> other pdf viewers show any difference between colors on the first and
> second pages (I run few tests uncommenting corresponding lines). At
> least for me. I am not sure how to measure accurately and objectively
> colors (I cannot rely upon much on my eyes comparing two close
> shades).
On my Linux box I used kcolorchooser to measure the colors and
I would guess that OSX provides a similar functionality. However,
try the case:

\pagecolor[HTML]{505050}  % page 2 is #021518

for which the change from page 1 (#505050) to page2 (#021518) is quite 
marked and your comments concerning visual perception do not apply. 
Actually, I've just tried it on my wife's XP box and there is no change in 
the page colours and so it looks like it is a Linux-specific bug. This is 
unfortunate as the pre-release program for Linux AR8.1.2 has just closed 
and so it might be some time before a bug fix can make it to a public AR 
release.

James

> 
> However it is a well-known effect that the visual perception of the
> same color changes if the surrounding objects change their colors; I
> suspect that the degree of this illusion could be individual.