Global brightness change compensation system and method

A pre-processing method for reducing identified brightness changes between a first video source frame and a subsequent second video source frame in a video frame sequence, the method comprising:

• a) receiving the video frame sequence, the sequence including the second source frame having an array of second source pixels;
• b) storing a first brightness compensated frame representing a brightness compensated version of the first source frame, the first compensated frame having an array of brightness compensated first pixels;
• c) pre-processing the second source frame using a brightness model with at least two model parameters to identify a brightness variation between a selected group of the second source pixels and a corresponding selected group of the compensated pixels;
• d) identifying the brightness of the second source frame by selecting a suitable set of the model parameters for each group of the second source pixels and compensated pixels, the suitable parameter set used to calculate a brightness offset for reducing the identified brightness variation from the group of second source pixels to more closely correspond to the brightness level of the compensated pixels, and
• e) producing a second brightness compensated source frame by applying the brightness offset to the second source frame;
• wherein the reduction of the brightness variation between the second source frame and the first compensated frame provides the second brightness compensated source frame for input to an encoder.

A computer program product for video frame pre-processing to reduce identified brightness changes between a first video source frame and a subsequent second video source frame in a video frame sequence, the computer program product comprising:

• a) a computer readable medium;
• b) an input module stored on the computer readable medium for storing the video frame sequence, the sequence including the second source frame having an array of second source pixels;
• c) a frame memory module coupled to the input module, the memory module for containing a first brightness compensated frame representing a brightness compensated version of the first source frame, the first compensated frame having an array of brightness compensated first pixels;
• d) a brightness pre-processor module coupled to the frame module, the pre-processor module having a brightness model with at least two model parameters for identifying a brightness variation between a selected group of the second source pixels and a corresponding selected group of the compensated pixels;
• e) a brightness filter module coupled to the pre-processor module, the filter module for selecting a suitable set of the model parameters for each group of the second source pixels and compensated pixels, the suitable parameter set used to calculate a brightness offset for reducing the identified brightness variation from the group of second source pixels to more closely correspond to the brightness level of the compensated pixels, thereby producing a second brightness compensated source frame;
• wherein the reduction of the brightness variation between the second source frame and the first compensated frame provides the second brightness compensated source frame for input to an encoder.