chage of colour in image processing

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naresh850

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Hello,

I would like to chage of colour in image.
My image is in YCbCr(4:2:2) format.

So i need to change the value of Cb and Cr.

Can anybody gives me different value of Cb and Cr for different colour?

Any help would be highly appriciated.

regards
NAresh
 

U CAN SIMPLY USE RGB2GRAY MATLAB COMMAND,RGB2HSI COMMAND
 

hello i m doing all the coding in real time on processor blackfin BF561

I cant use RGB

if you know somtnig about Cb and Cr values for different colours then please let me know
 

use the Gonzal & woods book
Digital Image Processing using matlab
see the chapter color image processing
 

Here is how you can do it.

1. Change YCbCr to RGB using following formula [From Wikipedia]
Code: 
8-bit R'G'B' from YCbCr (601)
=====================================================================
R'd = ( 298.082 * Y'                + 408.583 * Cr ) / 256 - 222.921
G'd = ( 298.082 * Y' - 100.291 * Cb - 208.120 * Cr ) / 256 + 135.576
B'd = ( 298.082 * Y' + 516.412 * Cb                ) / 256 - 276.836
.....................................................................

2. Modify the R,G,B values

3. Convert RGB back to YCbCr using following formula
Code: 
YCbCr (601) from "digital 8-bit R'G'B'  "
========================================================================
Y' = 16  + 1/256 * (   65.738  * R'd +  129.057  * G'd +  25.064  * B'd)
Cb = 128 + 1/256 * ( - 37.945  * R'd -   74.494  * G'd + 112.439  * B'd)
Cr = 128 + 1/256 * (  112.439  * R'd -   94.154  * G'd -  18.285  * B'd)
........................................................................
R'd, G'd, B'd in {0, 1, 2, ..., 255}
Y'               in {16, 17, ..., 235}
   with footroom in {1, 2, ..., 15}
        headroom in {236, 237, ..., 254}
        sync.    in {0, 255}
Cb, Cr           in {16, 17, ..., 240}
 

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