YUV is a family of color spaces used as a part of the Color image pipeline in video and digital photography systems [20]。 Y is the luminance component and U and V are the blue difference and red-difference chromatic purity components。 YUV is not an absolute color space。 It is a way of encoding RGB information。 The actual color display depends on the actual RGB colorants used to display the signal。 Therefore a value expressed as YUV is only predictable if standard RGB colorants are used [21]。

For efficiently compress the color information when the high performance of Ethernet transportation is acquired, convert color information from RGB color space to YUV form is necessary and the conversion relationship is defined as follows:

⎡Y ⎤ ⎡ 0。257 0。504 0。098 ⎤ ⎡ R ⎤    ⎡0。063⎤

⎢U ⎥  ⎢0。148    0。291 0。439 ⎥ ⎢G⎥  ⎢0。500⎥ (5)

Figure 5。   The Structure of RAW to RGB Module。

⎢⎥ ⎢ ⎥⎢⎥⎢ ⎥

information to t  the  final details  abo  t  the  view, but

⎢⎣V ⎥⎦

⎢⎣ 0。439

0。368

0。071⎥⎦ ⎢⎣ B ⎥⎦

⎢⎣0。500⎥⎦

most digital cameras in the market are use only one CMOS chip to obtain the view information for the perspective of cost。 The traditional way is using Bayer

When the signal is processed in an embedded   system,

to   design   a   unit   to   achieve   floating   calculation  is

complicated。 In regard to this matter, multiply the formula by 1024 and the result are rounded as follows:

⎡Y ⎤ ⎡ 263 516 100 ⎤ ⎡ R ⎤ ⎡ 66 ⎤

The stream format is:

Y0 ,U0 ,Y1,U1,Y2 ,U2 ,Y3 ,U3 ,Y4 ,V4 ,Y5 ,V5 ,Y6 ,V6 ,Y7 ,V7 。

The pixels that reconstitute are:

⎢U ⎥  ⎢152

298 450⎥ ⎢G⎥  ⎢512⎥

(6)

Line  1:  { Y0 ,U0 ,V4  },  { Y1,U1,V5 },  { Y2 ,U2 ,V6 },

⎢⎥ ⎢ ⎥⎢⎥ ⎢ ⎥

⎣⎢V ⎥⎦ ⎣⎢ 450

377

73⎥⎦ ⎢⎣ B ⎥⎦

⎢⎣512⎥⎦

{ Y3 ,U3 ,V7 }

The data process flow of RGB to YUV is presented in Fig。 6。

The main stream format of YUV is 4:4:4, 4:2:2, 4:2:0 and so on。 Each of them is save all Y component signal and loose some U and V component signal。 The quality of the image will not change。 We analyses the advantage of each stream format and optimize the format。

Line  2:  { Y4 ,U0 ,V4 },  { Y5 ,U1,V5 },  { Y6 ,U2 ,V6 },

{ Y7 ,U3 ,V7 }

D。SDRAM Control Module

The SDRAM is the storage of the image obtained from CMOS image sensor。 It is synchronization between the SDRAM and the image sensor that play an important role for the panoramic mosaic camera [22]。 Therefore, there are two separate SDRAM is used in the design, each SDRAM correspond to one image sensor。 To ensure the functional performance, the frequency breadth is calculated。