Dear all, as expressed by the title, I have a very strange behaviour between colors and figures. Here is the example :
\setupcolors[state=start]
\definecolor[gris][r=0.310,g=0.333,b=0.341]

\starttext
  \placefigure{}{\externalfigure[myfigure]}
  \color[gris]{\tfd Some text}
\stoptext

If myfigure is a PDF file, everything is ok with MKII, MKIV and XeTeX. If myfigure is a PNG file with transparency, then the "gris" color is ok with MKII but not with MKIV and XeTeX if the resulting document is read with Adobe Reader on Linux (when read with evince, colors are ok !!!!!). In the latter case, the "gris" color is very dark close to black and the green of myfigure becomes flashy...
Quite puzzling !