CloseView is a control panel that came with all Macs (or were made available to all Macs) beginning with System 7 through to Mac OS 9.2.2.
Using the CloseView control panel, you could magnify part of the display up to 16 times and to invert the colors of the display.
However, in some circumstances, the user could experience performance problems when using this control panel. To turn off CloseView, press command-option-O or open the CloseView control panel and click the Off button.