Patent ID: 8311327

Claim:
A backlit image detection system comprising: an input for receiving encoded color image data; a histogram calculator operable to calculate histogram data from received color image data; a detector operable to detect a mid-tone range in normalized histogram data; a selector operable to select a zone of normalized pixel counts within the mid-tone range; a point generator operable to generate data representative of an entry point and an exit point of the normalized histogram data relative to the selected zone, the point generator including: a filter operable to smooth a forward difference of the histogram data by application of a threshold value on the normalized histogram data, an adder operable to add histogram values at an extreme upper range and an extreme lower range of the normalized histogram data, a minimum value calculator operable to calculate a minimum value over the mid-tone range, and a comparator operable to generate the entry point in accordance with a comparison of the calculated minimum value with a preselected minimum value; a plateau detector operable to detect a plateau area in the normalized histogram data in the selected zone between the entry point and the exit point; and a backlit image detection signal generator operable to generate an output indicative as to whether a backlit image portion is present in the color image data in accordance with an output of the plateau detector.