does PHP support ancillary chunks in PNG images (background color)

[Bint]

Hi,

I want to create 24 bit PNG image files (red, green, blue, alpha) with
PHP -- that's easy enough. However, I would like to include a background
color value as well, as a default. The Wikipedia article for PNG images
states that PNG includes "ancillary" chunks, one of which is the background
value:

Ancillary chunks
Other image attributes that can be stored in PNG files include gamma values,
background color, and textual metadata information. PNG also supports color
management through the inclusion of ICC color space profiles.

a.. bKGD gives the default background color. It is intended for use when
there is no better choice available, such as in standalone image viewers
(but not web browsers, although Internet Explorer 6 and lower, which does
not support alpha transparency, will display this color as the background of
the PNG).

Is it possible to create a PNG image and file in PHP which includes one of
these 'bKGD' tags?

Thanks!
B