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Method for RGB to YCbCr color conversion algorithm, and YCbCr to CMYK color conversion algorithms, for parallel data-driven architecture

IP.com Disclosure Number: IPCOM000029813D
Publication Date: 2004-Jul-13
Document File: 5 page(s) / 52K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for RGB to YCbCr color conversion algorithm and YCbCr to CMYK color conversion algorithms for parallel data-driven architecture. Benefits include improved performance.

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Method for RGB to YCbCr color conversion algorithm, and YCbCr to CMYK color conversion algorithms, for parallel data-driven architecture

Disclosed is a method for RGB to YCbCr color conversion algorithm and YCbCr to CMYK color conversion algorithms for parallel data-driven architecture. Benefits include improved performance.

Background

RGB to YCbCr

              RGB to YCbCr conversion is the most commonly used color coordinate system for the compression of image and video signals. Y is the luminance component and Cb and Cr are the chrominance components. The primary red, green, blue inputs (R, G, and B) can be converted as follows:

Y = 0.299(R — C) + C + 0.114(B — C)

Cb = 0.564(B — Y)

Cr = 0.713(R — Y)

Alternatively, YCbCr values can be converted to RGB (see Figure 1).

YCbCr to CMYK

              Two color spaces used for printing purposes are the subtractive color spaces CMY and CMYK. The subtractive color space CMY produces the primary colors cyan, magenta, and yellow. The YCbCr to CMYK transformation is defined as:

C = 255 – Y – 1.4021(Cr-128)

M = 255 - Y + 0.3441(Cb-128) + 0.7142(Cr-128)

Y = 255 – Y – 1.7718(Cb -128)

              The CMYK color space is the model used for the four color printing process and uses the four color components Ck, Mk, Yk, and K. The fourth component, K, represents the additional color black. The following formula computes K and Ck, Mk, and Yk values based on the CMY values above:

K = min (C, M, Y)

Ck = C – K             Mk = M – K Yk = Y - K

General description

              The disclosed method is an effective implementation of two color conversion algorithms, RGB to YCbCr and YCbCr to CMYK, using multiple instruction multiple data (MIMD) parallel programmable media architecture.

Advantages

              The disclosed method provides advantages, including:

•             Improved performance due to taking full advantage of all processing elements running in parallel

 

Detailed description

              The disclosed method includes color conversion algorithms that utilize image signal processors (ISPs). Internal to each ISP are several processing elements:

•             Input processing element (IPE)

•             Output processing element (OPE)

•             Two multiplier accumulator processing elements, designated as MACPE2 and MACPE3

•             General processing element (GPE)

              One memory storage element (MCH) and two slots are reserved for hardware accelerator processing elements.

              General purpose registers (GPRs) serve as the interconnect between the various processing elements in an ISP. The GPRs are 16 bits wide with 8 additional bits called data valid (DV) bits. The DV-bits...