图像处理1:RGB888_YCbCr444

前言 正文 一、YCbCr 1.1 什么是YCbCr

Y通道： 表示图像的强度、亮度 Cb通道： 表示图像蓝色 色度 Cr通道： 表示图像红色 色度

1.2 为什么要用YCbCr

减少色彩信息，进而来减少存储空间 参考资料

对比

用RGB表示一张图片，其中GRB三个通道分别如下： 用YCbCr表示的图像如下：

1.3 如何实现

1. 计算公式 Y = ( 77 ∗ R + 150 ∗ G + 29 ∗ B ) > > 8 C b = ( − 43 ∗ R − 85 ∗ G + 128 ∗ B + 32768 ) > > 8 C r = ( 128 ∗ R − 107 ∗ G − 21 ∗ B + 32768 ) > > 8 Y = (77 *R + 150*G + 29 *B)>>8\\ Cb = (-43*R - 85 *G + 128*B + 32768)>>8\\ Cr = (128*R - 107*G - 21 *B + 32768)>>8 Y=(77∗R+150∗G+29∗B)>>8Cb=(−43∗R−85∗G+128∗B+32768)>>8Cr=(128∗R−107∗G−21∗B+32768)>>8
2. 流水线：相乘——相加——右移8位（舍弃低8位）
3. 行信号打拍

`timescale 1ns / 1ps

module RGB888_YCbCr444
(
	//global clock
	input					clk,  				//cmos video pixel clock
	input					rst_n,				//global reset

	//Image data prepred to be processd
	input					per_frame_vsync,	//Prepared Image data vsync valid signal
	input					per_frame_href,		//Prepared Image data href vaild  signal
	input					per_frame_clken,	//Prepared Image data output/capture enable clock	
	input		[7:0]		per_img_red,		//Prepared Image red data to be processed
	input		[7:0]		per_img_green,		//Prepared Image green data to be processed
	input		[7:0]		per_img_blue,		//Prepared Image blue data to be processed
	
	//Image data has been processd
	output				    post_frame_vsync,	//Processed Image data vsync valid signal
	output				    post_frame_href,	//Processed Image data href vaild  signal
	output				    post_frame_clken,	//Processed Image data output/capture enable clock	
	output		[7:0]	    post_img_Y,			//Processed Image brightness output
	output		[7:0]	    post_img_Cb,		//Processed Image blue shading output
	output		[7:0]	    post_img_Cr			//Processed Image red shading output
);

//==========================================parameter===========================================================
	/*********************************************
	//Refer to  page 5
		Y 	=	(77 *R 	+ 	150*G 	+ 	29 *B)>>8
		Cb 	=	(-43*R	- 	85 *G	+ 	128*B)>>8 + 128
		Cr 	=	(128*R 	-	107*G  	-	21 *B)>>8 + 128

		Y 	=	(77 *R 	+ 	150*G 	+ 	29 *B)>>8
		Cb 	=	(-43*R	- 	85 *G	+ 	128*B + 32768)>>8
		Cr 	=	(128*R 	-	107*G  	-	21 *B + 32768)>>8
	**********************************************/

//==========================================reg=================================================================
reg	[15:0]	img_red_r0,		img_red_r1,		img_red_r2;	
reg	[15:0]	img_green_r0,	img_green_r1,	img_green_r2; 
reg	[15:0]	img_blue_r0,	img_blue_r1,	img_blue_r2;

reg	[15:0]	img_Y_r0;
reg	[15:0]	img_Cb_r0; 
reg	[15:0]	img_Cr_r0; 

reg	[7:0]	img_Y_r1;
reg	[7:0]	img_Cb_r1;
reg	[7:0]	img_Cr_r1;

reg	[2:0]	per_frame_vsync_r;
reg	[2:0]	per_frame_href_r;	
reg	[2:0]	per_frame_clken_r;
//==========================================wire=================================================================

//==========================================assign=================================================================
assign	post_frame_vsync 	= 	per_frame_vsync_r[2];
assign	post_frame_href 	= 	per_frame_href_r [2];
assign	post_frame_clken 	= 	per_frame_clken_r[2];
	
// 当有行信号时，就输出
assign	post_img_Y 	= 	post_frame_href ? img_Y_r1 : 8'd0;
assign	post_img_Cb =	post_frame_href ? img_Cb_r1: 8'd0;
assign	post_img_Cr = 	post_frame_href ? img_Cr_r1: 8'd0;

//==========================================always=================================================================

	// 第一级流水线：执行乘法
	always@(posedge clk or negedge rst_n)begin
		if(!rst_n)
			begin
			    img_red_r0