I am attempting to replace several shape objects with TRANSPARENT images, but GemBox does not support (respect) the Transparency of the Image.
Excel supports setting a TRANSPARENT color for images (allowing all pixels "behind" the image object [of that specified color] to "show through" the image).
Official response
Mario - GemBox
Hi, This feature request has been implemented and is available in the latest versions of GemBox.Spreadsheet. Regards, Mario