The Vivado HLS tool supports variable image sizes on the input and outputs. The loop counters of each loop nest should be compared against some variable value, typically coming from the outside world. In addition, the tripcount pragma, which does not impact the result of synthesis, can be used to provide meaningful values during reporting, giving the ability to tune performance for the image range. In such an implementation, the line buffers and memory should be sized on the largest image size the design would support. There is no requirement that all images must be the same size, just be sure to allocate enough memory in hardware to handle the largest image.