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由于fpga实现除法相对复杂，故将除法变为乘法再移位。因此每种方法对图像输入数据均分3步进行，极其有效信号打三拍处理。
`timescale 1ns / 1ps
//
// Description: 彩色图像灰度化
//
module image_rgb2gray(input wire clk ,input wire reset ,input wire valid_i ,input wire [23:0] img_data_i,output wire valid_o ,output wire [23:0] img_data_o
);//常量parameter MODE = 1; //0表示加权平均法，1表示平均法 //Y=0.299*R十0.587*G+0.114*Bparameter C0 = 9'd306; //0.299*1024;parameter C1 = 10'd601;//0.587*1024;parameter C2 = 7'd117; //0.114*1024;//参数声明wire [7:0] R, G, B;assign {R, G, B} = img_data_i;generate if (MODE) begin//1-平均法 1/3 * 512 = 171reg valid_d1; reg [9:0] RGB_avr;reg valid_d2; reg [16:0] RGB_avr_m;reg valid_d3; reg [7:0] RGB_new;always@(posedge clk or posedge reset) beginif(reset) beginvalid_d1 <= 'b0;RGB_avr <= 'b0;end else beginvalid_d1 <= valid_i;RGB_avr <= R + G + B;endend//最大值不可能超过255*3*171 = 17'd130815always@(posedge clk) beginRGB_avr_m <= RGB_avr * 8'd171;endalways@(posedge clk or posedge reset) beginif(reset) beginvalid_d2 <= 'b0;end else beginvalid_d2 <= valid_d1;endend//最大值不可能超过255always@(posedge clk or posedge reset) beginif(reset) beginvalid_d3 <= 'b0;RGB_new <= 'b0;end else beginvalid_d3 <= valid_d2;RGB_new <= RGB_avr_m[16:9];endendassign valid_o = valid_d3;assign img_data_o = {3{RGB_new}};end else begin//0-加权平均法reg valid_d1;reg [16:0] Y_R_m;reg [17:0] Y_G_m;reg [14:0] Y_B_m;reg valid_d2;reg [17:0] Y_s;//最大值，当RGB都等于255时，(C0 + C1 + C2)*255 = 1024*255；不会出现负数reg valid_d3;reg [7:0] Y;always@(posedge clk ) beginY_R_m <= R*C0;Y_G_m <= G*C1;Y_B_m <= B*C2;endalways@(posedge clk or posedge reset) beginif(reset) beginvalid_d1 <= 0;end else beginvalid_d1 <= valid_i;endend always@(posedge clk or posedge reset) beginif(reset) beginY_s <= 0;valid_d2 <= 0;end else beginif(valid_d1) beginY_s <= Y_R_m + Y_G_m + Y_B_m;endvalid_d2 <= valid_d1;endendalways@(posedge clk or posedge reset) beginif(reset) beginY <= 0;valid_d3 <= 0;end else beginif(valid_d2) beginY <= Y_s[17:10];endvalid_d3 <= valid_d2;endend assign valid_o = valid_d3;assign img_data_o = {3{Y}};end endgenerateendmodule
