Active pixel image cell with embedded memory and pixel level signal processing capability

An imaging array, comprising:

• (a) a plurality of active pixel image cells arranged into rows and columns, wherein each active pixel image cell further comprises
• (i) a photosensor which generates an electrical signal representing an output of the sensor;
• (ii) a first control element for transferring an electrical signal corresponding to a first output of the photosensor to a storage element;
• (iii) a storage element for storing the electrical signal corresponding to the first output of the photosensor;
• (iv) a second control element for causing an electrical signal corresponding to a second output of the photosensor to be produced as a first output of the pixel;
• and
• (v) a third control element for causing the electrical signal stored in the storage element to be produced as a second output of the pixel substantially simultaneously with the production of the first output of the pixel;
• and
• (b) at least one signal processing element having as two inputs the first and second outputs of an active pixel image cell in the imaging array and having an output which is a result of performing a signal processing operation on the two inputs.

A method of operating an active pixel imaging cell, comprising:

• generating a first photosensor output signal from a photosensor contained in the pixel;
• transferring the first photosensor output signal to a storage element contained in the pixel;
• generating a second photosensor output signal from the photosensor contained in the pixel;
• providing the second photosensor output signal as a first pixel output;
• and
• providing the first photosensor output signal stored in the storage element as a second pixel output substantially simultaneously with the first pixel output.

An active pixel imaging cell, comprising:

• a photosensor which generates an electrical signal representing an output of the photosensor;
• a first and a second storage element, wherein each storage element has a first and a second node, with the first node of each storage element electrically connected to an output node of the photosensor;
• a first control element for selectively grounding the second node of the first storage element;
• a second control element for selectively grounding the second node of the second storage element;
• and
• a third control element for transferring a signal present at the second node of the first or second storage element to an output node of the pixel.

A method of operating an active pixel imaging cell, comprising:

• generating a first photosensor output signal from a photosensor contained in the pixel;
• transferring the first photosensor output signal to a first storage element contained in the pixel;
• generating a second photosensor output signal from the photosensor contained in the pixel;
• transferring the second photosensor output signal to a second storage element contained in the pixel;
• generating a signal representing a difference between the first and second photosensor outputs;
• and
• transferring the signal representing the difference between the first and second photosensor outputs to an output node of the pixel.