`TFPWriterPNM`
pt		SaveHeader
pt		InternalWrite
		GuessColorDepthOfImage
		GetColorDepthOfExtension
		GetFileExtension
		Create

`TFPCustomImageWriter`
pt		InternalWrite
pt		InternalBeginFrames
pt		InternalWriteFrame
pt		InternalEndFrames
		ImageWrite
		FrameKinds
		BeginFrames
		WriteNextFrame
		EndFrames

`TFPCustomImageHandler`
pt		Progress
		Create