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Method for contrast enhancement with histogram equalization

IP.com Disclosure Number: IPCOM000033842D
Publication Date: 2004-Dec-29
Document File: 8 page(s) / 101K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for contrast enhancement with histogram equalization. Benefits include improved functionality and improved performance.

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Method for contrast enhancement with histogram equalization

Disclosed is a method for contrast enhancement with histogram equalization. Benefits include improved functionality and improved performance.

Background

              An multiservice packet transport platform (MXP) digital media processor is a highly parallel multiple instruction multiple data (MIMD) image processor. Intrinsic to its design is the abundance of data I/O connections between its image signal processors (ISPs), its direct memory access (DMA) memory channels, and its external interfaces. A mesh-connected grid of quad ports flexibly route data among the ISPs (see Figure 1).

             
              Each ISP includes five processing elements (PEs) of the following types:

•             Input (IPE)

•             Output (OPE)

•             Multiplier Accumulator (MACPE)

•             General (GPE)

      The PEs are programmed using MXP assembly language, one memory controller hub (MCH) storage element, and two slots reserved for hardware accelerator processing elements (see Figure 2).

              General purpose registers (GPRs) provide the interconnection between the various processing elements in an ISP. The GPRs are 16-bits wide with 8 additional data valid (DV) bits, which are used as an address to designate the data receiver.

General description

              The disclosed method is a histogram equalization algorithm for use with an MIMD digital media processor and architecture. The method uses multiple processing elements (PEs) within an image signal processor (ISP) and multiple quad ports for optimal implementation.

Advantages

              Some implementations of the disclosed structure and metho provide one or more of the following advantages:

•             Improved functionality due to contrast enhancement with histogram equalization

•             Improved performance due to improved processing efficiency using the parallel and programmable features of the MXP image processing architecture

 


Detailed description

              The disclosed method includes an algorithm that distributes the gray levels within an image so that every gray level is equally likely to occur. It produces a new image with a histogram that is uniformly distributed. The method increases the contrast of a low-contrast image. The processing can make features observable that were not visible in the original image.

              The histogram-equalization algorithm performs three major steps (see Figure 3):

1.           Calculate a global image histogram.
2.           Calculate a look-up table (LUT).
3.           Create a new image.

              A single ISP, designated as ISP2, processes stages 1 and stage 3.

Calculate a global image histogram

              The original image data is written into double data rate (DDR) random access memory (RAM), designate...