To use this widget type the name of an image (.i2i format) to read in. The image must be of the same dimensions as the currently present image. If two images are currently present, the user is queried as to which of the two images should be replaced. If only one image is currently in DAVE, then it will be replaced; I don't think that the new image can become image2 (the "red" image).
The menu provides for whether you want the image transposed before it is used. The default is not to transpose the image.