自動白平衡

依R, G, B 成份，加總整個畫面的像素值 ，先調整成 K = 128

改　ltp_controller.v

宣告

1. reg [26:0] sum_R, sum_G, sum_B; // the total value of R, G, B
2. reg [16:0] average_R, average_G, average_B; 
3. reg [18:0] gray_average; // K: gray_average = (R_average+G_average+B_average)/3
4. reg [26:0] temp_R, temp_G, temp_B;
5. wire [7:0] new_R, new_G, new_B;

計算

1. always@(posedge iCLK  or negedge iRST_n) // sum all the component
2. begin
3. if (!iRST_n)
4. begin
5. sum_R <= 0; // sum R
6. sum_G <= 0; // sum G
7. sum_B <= 0; // sum B
8. end
9. else if (y_cnt == 0 && x_cnt == (H_LINE-1))
10. begin
11. sum_R <= 0; // sum R
12. sum_G <= 0; // sum G
13. sum_B <= 0; // sum B
14. end
15. else if (display_area)
16. begin
17. sum_R <= sum_R + read_red; // sum R
18. sum_G <= sum_G + read_green; // sum G
19. sum_B <= sum_B + read_blue; // sum B
20. temp_R <= 375*{read_red,7'b0}   / average_R; // K = 128, R*K/(R_av/375)
21. temp_G <= 375*{read_green,7'b0} / average_G; // K = 128, R*K/(G_av/375)
22. temp_B <= 375*{read_blue,7'b0}  / average_B; // K = 128, R*K/(B_av/375)
24. end
25. else if (y_cnt == (V_LINE-1) && x_cnt == (H_LINE-1))
26. begin
27. average_R <= sum_R[26:10]; // 375 times (800*480/1024=375)
28. average_G <= sum_G[26:10];
29. average_B <= sum_B[26:10];
30. end
31. end

輸出

1. always@(posedge iCLK or negedge iRST_n)
2. begin
3. if (!iRST_n)
4. begin
5. oHD <= 1'd0;
6. oVD <= 1'd0;
7. oDEN <= 1'd0;
8. oLCD_R <= 8'd0;
9. oLCD_G <= 8'd0;
10. oLCD_B <= 8'd0;
11. end
13. else if (y_cnt < (Vertical_Front_Porch+240))
14. begin
15. oHD <= mhd;
16. oVD <= mvd;
17. oDEN <= mden;
18. oLCD_R <= temp_R > 255 ? 255: temp_R[7:0];
19. oLCD_G <= temp_G > 255 ? 255: temp_G[7:0];
20. oLCD_B <= temp_B > 255 ? 255: temp_B[7:0];
21. 
    
22. end
23. else
24. begin
25. oHD <= mhd;
26. oVD <= mvd;
27. oDEN <= mden;
28. oLCD_R <= read_red;
29. oLCD_G <= read_green;
30. oLCD_B <= read_blue;
31. end
32. end

結果：有部分雜訊出現，推測是除法太慢

待改進
https://blog.csdn.net/a874176979/article/details/79853934