You can add transparent pictures to a PDF using our MBS Real Studio DynaPDF Plugin. The InsertPicture function can be called with a picture and a mask picture. This way you can get transparent pictures easily into a PDF.
You insert a picture like this:
Where p is the picture, m is the mask picture and the 4 other parameters are the rectangle where to place the picture.
call d.InsertPicture(p, m, x, y, w, h)
Of course you also can use transparent picture files (GIF, PNG, TIFF) with InsertImage function. Or if you have picture in memory buffer, use InsertImageFromBuffer. For selecting the right picture in a multi picture tiff file, use InsertImageEx.
PS: You only need the DynaPDF Starter Edition for this.