Apparatus and method for histogram stretching
OwnerEric Jeffrey, Barinder Raiinventors
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Abstract
A graphics controller including a memory and a contrast adjustment module is provided to perform on-board histogram stretching. The memory is configured to store a histogram table for a digital image. The contrast adjustment module is configured to read the histogram table stored in the memory and compute a histogram stretching transfer function based on the read histogram table. The contrast adjustment module is further configured to apply the computed histogram stretching transfer function to digital image data to be subsequently received by the contrast adjustment module.
Claims20
A graphics controller, comprising:
- a memory configured to store a histogram table for a digital image;
- and
- a contrast adjustment module configured to read the histogram table stored in the memory, the contrast adjustment module being further configured to compute a histogram stretching transfer function based on the read histogram table and apply the computed histogram stretching transfer function to digital image data to be subsequently received by the contrast adjustment module.
A contrast adjustment module of a graphics controller, comprising:
- a stretching point computation module configured to compute a first stretching point and a second stretching point to be used in performing a histogram stretching operation, each of the first and second stretching points corresponding to a respective pixel value;
- a transfer function computation module configured to compute a portion of a histogram stretching transfer function based on the first and second stretching points and digital image data to be received by the contrast adjustment module;
- a multiplexer configured to output a contrast adjusted pixel value according to a select signal to be received by the multiplexer, the multiplexer being further configured to receive as an input the portion of the histogram stretching transfer function as computed by the transfer function computation module;
- and
- a comparison module configured to generate the select signal for the multiplexer, the select signal being generated based on the first and second stretching points and the digital image data to be received by the contrast adjustment module.
A method for operating a graphics controller to adjust contrast of a digital image received from a digital imaging device, comprising:
- operating a contrast adjustment module within the graphics controller to read a histogram table stored in a memory of the graphics controller;
- operating the contrast adjustment module to compute a histogram stretching transfer function to be applied to digital image data received from the digital imaging device, the histogram stretching function being based in part on the histogram table read from the memory;
- receiving the digital image data at the contrast adjustment module;
- and
- operating the contrast adjustment module to apply the histogram stretching transfer function to the received digital image data, wherein application of the histogram stretching transfer function to the received digital image data serves to adjust a contrast of a digital image defined by the received digital image data.
Dependencies are inferred from the claim text.