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 topage 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 <= 0; img_red_r1 <= 0; img_red_r2 <= 0; img_green_r0 <= 0; img_green_r1 <= 0; img_green_r2 <= 0; img_blue_r0 <= 0; img_blue_r1 <= 0; img_blue_r2 <= 0; end else begin
			    img_red_r0 <= per_img_red * 8'd77; img_red_r1 <= per_img_red * 8'd43; img_red_r2 <= per_img_red * 8'd128; img_green_r0 <= per_img_green * 8'd150; img_green_r1 <= per_img_green * 8'd85; img_green_r2 <= per_img_green * 8'd107; img_blue_r0 <= per_img_blue * 8'd29; img_blue_r1 <= per_img_blue * 8'd128; img_blue_r2 <= per_img_blue * 8'd21; end
	end // 第二级流水线：执行加法 always@(posedge clk or negedge rst_n)begin if(!rst_n) begin
			    img_Y_r0 <= 0; img_Cb_r0 <= 0; img_Cr_r0 <= 0; end else begin
			    img_Y_r0 <= img_red_r0 + img_green_r0 + img_blue_r0; img_Cb_r0 <= img_blue_r1 - img_red_r1 - img_green_r1 + 16'd32768; img_Cr_r0 <= img_red_r2 + img_green_r2 + img_blue_r2 + 16'd32768; end
	end // 第三级流水线：右移8位=除以256 ？？是的，往右移8位，把低8位挤走了 always@(posedge clk or negedge rst_n)begin if(!rst_n) begin
			    img_Y_r1 <= 0; img_Cb_r1 <= 0; img_Cr_r1 <= 0; end else begin
			    img_Y_r1 <= img_Y_r0 [15:8]; img_Cb_r1 <= img_Cb_r0[15:8]; img_Cr_r1 <= img_Cr_r0[15:8]; end
	end //------------------------------------------ //lag 3 clocks signal sync  // 上面有3级流水线，因此经历了3个时钟，于是需要把输入的行、使能信号等进行3次打拍操作 // 这里的打拍操作比较厉害，值得学习！！ //--------------------------------------------- always@(posedge clk or negedge rst_n)begin if(!rst_n) begin
			    per_frame_vsync_r <= 0; per_frame_href_r <= 0; per_frame_clken_r <= 0; end else begin
			    per_frame_vsync_r <= {per_frame_vsync_r[1:0], per_frame_vsync}; per_frame_href_r <= {per_frame_href_r [1:0], per_frame_href}; per_frame_clken_r <= {per_frame_clken_r[1:0], per_frame_clken}; end
	end //==========================================状态机================================================================= //==========================================模块例化================================================================= endmodule