// Load RGB image
Reg_Set(10, "|(USER_MACRO)\example.ppm")
Call("LOAD_PPM")

// Convert to grayscale
#10 = Buf_Num
Call("RGB_TO_GRAYSCALE")
Buf_Switch(#10) Buf_Quit(OK)

// Convert to RGB
Call("GRAYSCALE_TO_RGB")

// Save the image
Reg_Set(10, "|(USER_MACRO)\example_gray.ppm")
Call("SAVE_PPM")

// Cleanup and exit
Buf_Switch(#20) Buf_Quit(OK)
return