PngTransparency

Default: 255
Example: none

Sets the last colour that is used as a transparent in a PNG of GIF file when a picture is saved as a PNG of GIF file.

PngWhiteTrans

Default: True
Example: none

Represents the last choice for the use of transparency in a PNG or a GIF file when a picture is saved as a PNG of GIF file.

See 'save picture' and 'save pictures as'