What if images produced from PDFs within the timeline of LiveCycle need to all be the same size? PDFs that are the same size, dimension-wise, can turn out as images of different sizes after processing with the toImage activity. For example, two PDFs could be 8.5 x 11 inches in size. But one would convert to an image that is 1700 x 2200 pixels in size and the other would convert to an image that is 2550 x 3300 pixels in size.
Use the same DPI argument for each of the PDFs. The resulting images will not be an exact match with one another, however. In my test a variation of ten pixels or so could be seen as the result of differences in the areas of the PDF page that are converted to image. But PDFs that are the same dimensions before conversions result in images that are the same pixel height and width (or very close to it).
The documentation for the toImage operation of the Convert PDF service