Electronic devices may include image sensors having image pixel arrays with image pixels arranged in pixel rows and pixel columns. Each pixel column may be coupled to an active and an inactive current supply circuit. Each active current supply circuit may form a portion of a current mirror circuit that includes a common current source and a common input transistor. Each active current supply circuit may include a mirror transistor for mirroring current that flows through the common input transistor and a permanently enabled enabling transistor for activating that mirror transistor. Mirrored current that flows through a particular active mirror transistor may be supplied to image pixels in the pixel column associated with that particular mirror transistor. Each inactive current supply circuit may include a mirror transistor coupled to the input transistor and a permanently disabled enabling transistor.