A method of correcting an image for ambient light in an optical touch-sensitive device, the optical touch-sensitive device comprising a screen, a light source and an image sensor with two or more fields of pixels, the method comprising: integrating a first field of pixels in an image data frame for a different duration of ambient light exposure than a second field of pixels in the image data frame, comprising: exposing the image sensor for an "on" state interval during which the light source is in an "on" state and for an "off' state interval during which the light source is in an "off' state; and for alternating frames n and n+1: for frame n, reading intensity levels of the first field of pixels after integration of one "on" state interval, and then reading levels of the second field of pixels after integration of one "on" state interval and two "off' state intervals; and for frame n+1, reading intensity levels of the second field of pixels after integration of one "on state interval, and then reading levels of the first field pixels after integration of one "on" state interval and two "off' state intervals; reading intensity data from the first field of pixels and the second field of pixels; determining an ambient light value for one or more pixels in the image data frame from the intensity data, utilizing these differences in intra-frame and/or inter-frame ambient light exposure; and adjusting one or more pixels of the data frame for ambient light based upon the ambient light value. integrating a first field of pixels in an image data frame for a different duration of ambient light exposure than a second field of pixels in the image data frame, comprising: exposing the image sensor for an "on" state interval during which the light source is in an "on" state and for an "off' state interval during which the light source is in an "off' state; and for alternating frames n and n+1: for frame n, reading intensity levels of the first field of pixels after integration of one "on" state interval, and then reading levels of the second field of pixels after integration of one "on" state interval and two "off' state intervals; and for frame n+1, reading intensity levels of the second field of pixels after integration of one "on state interval, and then reading levels of the first field pixels after integration of one "on" state interval and two "off' state intervals; exposing the image sensor for an "on" state interval during which the light source is in an "on" state and for an "off' state interval during which the light source is in an "off' state; and for alternating frames n and n+1: for frame n, reading intensity levels of the first field of pixels after integration of one "on" state interval, and then reading levels of the second field of pixels after integration of one "on" state interval and two "off' state intervals; and for frame n+1, reading intensity levels of the second field of pixels after integration of one "on state interval, and then reading levels of the first field pixels after integration of one "on" state interval and two "off' state intervals; for frame n, reading intensity levels of the first field of pixels after integration of one "on" state interval, and then reading levels of the second field of pixels after integration of one "on" state interval and two "off' state intervals; and for frame n+1, reading intensity levels of the second field of pixels after integration of one "on state interval, and then reading levels of the first field pixels after integration of one "on" state interval and two "off' state intervals; reading intensity data from the first field of pixels and the second field of pixels; determining an ambient light value for one or more pixels in the image data frame from the intensity data, utilizing these differences in intra-frame and/or inter-frame ambient light exposure; and adjusting one or more pixels of the data frame for ambient light based upon the ambient light value.