The cpdf_place_inline_image() function places an image created with the php image functions on the page at position (x-coor, y-coor). The image can be scaled at the same time.
The optional parameter mode determines the unit length. If it's 0 or omitted the default unit as specified for the page is used. Otherwise the coordinates are measured in postscript points disregarding the current unit.
See also cpdf_import_jpeg().