Method and apparatus for enhancing the dynamic range of a CCD sensor

An imaging system for responding to a range of image intensities, comprising:

• an image input for receiving an image from an exterior environment;
• an image sensor for sensing the image and for generating an electrical signal in response thereto, said image sensor including at least one charge well for collecting charge in response to the image during an integration period having a start and an end, said integration period being defined as including a first half and a second half with said first half beginning at said start of said integration period and said second half terminating at said end of said integration period, said at least one charge well having a variable well depth;
• an intensity unit, located between said image input and said image sensor, for adjusting an image intensity of the image before the image reaches said image sensor;
• and
• a control subsystem, coupled to said image sensor and said intensity unit, that increases a high end intensity of said range of intensities by decreasing overall said image intensity during said integration period while increasing overall said well depth of said at least one charge well during said integration period wherein, in the event that said image intensity, during at least said first half of said integration period is substantially the same, said control subsystem includes at least a first controller that controls said well depth of said at least one charge well such that said well depth increases at least during some portion of said second half of said integration period and, in the event that said image intensity, during greater than three-quarters of said integration period is substantially the same, said control subsystem includes at least a first controller that controls said well depth of said at least one charge well such that said well depth increases at least during said second half of said integration period, and in the event that said image intensity, during at least a majority of said integration period decreases in a step-wise manner, said control subsystem includes at least a first controller that controls said well depth of said at least one charge well such that said well depth increases during at least said second half of said integration period and in which, under control of said control subsystem, said image intensity has at least a first magnitude that occurs closer to said start than to said end of said integration period and during at least some of said second half of said integration period, said image intensity has at least one decreased magnitude that is less than said first magnitude and at the same time said image intensity has said at least one decreased magnitude, said well depth of said at least one charge well increases from at least a first depth to at least a second depth.