The Zoomify Image Viewer can display crosshairs centered in the display. The HTML parameter zCrosshairsVisible=1 will enable this effect. In addition, the Zoomify JavaScript functions Z.Utils.drawCrosshairs() and Z.Utils.hideCrosshairs() can be used to set properties of the crosshairs and to hide them. See the Zoomify Parameter List in the Documentation folder and the Zoomify Function in the Developer Resources folder for details.