LabVIEW
systematic documentation errors in Vision
Many Vision function help descriptions contain an ad hoc note reading "Note: This VI modifies the source image. If you need the original source image, create a copy of the image using the IMAQ Copy before using this VI." This should read: “Note: This VI modifies the source image. If you need the original source image, create a copy of the image using the IMAQ Copy before using this VI, or wire a separate destination image to the Image Dst input."
Additionally, there are Vision functions that modify the source image if no destination image is wired that do not have the note in thier help description. For instance; LowPass, CannyEdgeDetection, FillHole, Label,... etc.
You may wish to remedy the inconsistency by removing this note. In order to avoid race conditions, the programmer already has to know that the image wire only carries a pointer. It is rather intuitive that the VI modifies the image space that belongs to the pointer.
If you wish to leave this note in the help files, then you need to correct it. Your note indicates that even if the Dst input is wired, that the source image might be modified. This requires a programmer to either test several Vision functions to determine that your note is erroneous, or to make unnecessary copies of images in the false belief that the note is correct.
If you are going to leave the note in half of the vision functions, then you need to place the same note in all vision functions that modify the source image if Image Dst is not wired to a separate image. Otherwise, this gives the impression that the source image is not being modified if such behavior is not noted in the help description.
Additionally, there are Vision functions that modify the source image if no destination image is wired that do not have the note in thier help description. For instance; LowPass, CannyEdgeDetection, FillHole, Label,... etc.
You may wish to remedy the inconsistency by removing this note. In order to avoid race conditions, the programmer already has to know that the image wire only carries a pointer. It is rather intuitive that the VI modifies the image space that belongs to the pointer.
If you wish to leave this note in the help files, then you need to correct it. Your note indicates that even if the Dst input is wired, that the source image might be modified. This requires a programmer to either test several Vision functions to determine that your note is erroneous, or to make unnecessary copies of images in the false belief that the note is correct.
If you are going to leave the note in half of the vision functions, then you need to place the same note in all vision functions that modify the source image if Image Dst is not wired to a separate image. Otherwise, this gives the impression that the source image is not being modified if such behavior is not noted in the help description.
