https://github.com/birdybro/rgb_conv_verilog

different rgb colorspace conversion techniques from rgb_xxx to rgb_888
https://github.com/birdybro/rgb_conv_verilog

Last synced: 17 days ago
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different rgb colorspace conversion techniques from rgb_xxx to rgb_888

• Host: GitHub
• URL: https://github.com/birdybro/rgb_conv_verilog
• Owner: birdybro
• License: mit
• Created: 2023-10-31T16:09:43.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-01-17T14:23:00.000Z (11 months ago)
• Last Synced: 2024-12-01T07:07:41.168Z (22 days ago)
• Language: Verilog
• Homepage:
• Size: 19.5 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# rgb_conv_verilog

different rgb colorspace conversion techniques from rgb_xxx to rgb_888 for fpga video

## rgb_222 to rgb_888 conversion with verilog/systemverilog using concatenation

this one's the easiest, there are no issues with scaling the colors up since it divides evenly (i think):

```sv

  logic [1:0] r_2, g_2, b_2;

  logic [7:0] r_8, g_8, b_8;

  always_comb begin

    r_8 = {4{r_2[1]}, 4{r_2[0]}};

    g_8 = {4{g_2[1]}, 4{g_2[0]}};

    b_8 = {4{b_2[1]}, 4{b_2[0]}};

  end

  assign VGA_R = r_8;

  assign VGA_G = g_8;

  assign VGA_B = b_8;

```

## rgb_333 to rgb_888 conversion with verilog/systemverilog using a generated LUT

add rgb333_to_rgb888.* files to your project

for includes in qip:

```ini

set_global_assignment -name QIP_FILE rtl/rgb333_to_rgb888.qip

```

and then add code to instantiate the module:

```sv

  logic [2:0] r_3, g_3, b_3;

  logic [7:0] r_8, g_8, b_8;

  rgb333_to_rgb888 rgb333_to_rgb888

  (

    .address({r_3, g_3, b_3}),

    .clock(clk_vid), // video clock, not pixel clock!

    .q({r_8, g_8, b_8)

  );

  assign VGA_R = r_8;

  assign VGA_G = g_8;

  assign VGA_B = b_8;  

```

## rgb_555 to rgb_888 conversion with verilog/systemverilog using linear interpolation

```sv

  logic [4:0] r_5, g_5, b_5;

  logic [7:0] r_8, g_8, b_8;

  always_comb begin

    r_8 = (r_5 << 3) + (r_5 >> 2);

    g_8 = (g_5 << 3) + (g_5 >> 2);

    b_8 = (b_5 << 3) + (b_5 >> 2);

  end

  assign VGA_R = r_8;

  assign VGA_G = g_8;

  assign VGA_B = b_8;

```

## rgb_565 to rgb_888 conversion with verilog/systemverilog using concatenation

```sv

  logic [4:0] r_5, b_5;

  logic [5:0] g_6

  logic [7:0] r_8, g_8, b_8;

  always_comb begin

    r_8 = {r_5, r_5[2:0]};

    g_8 = {g_6, g_6[1:0]};

    b_8 = {b_5, b_5[2:0]};

  end

  assign VGA_R = r_8;

  assign VGA_G = g_8;

  assign VGA_B = b_8;

```

## rgb_565 to rgb_888 conversion with verilog/systemverilog using shifts (less accurate)

```sv

  logic [4:0] r_5, b_5;

  logic [5:0] g_6

  logic [7:0] r_8, g_8, b_8;

  always_comb begin

    r_8 = r_5 << 3;

    g_8 = g_6 << 2;

    b_8 = b_5 << 3;

  end

  assign VGA_R = r_8;

  assign VGA_G = g_8;

  assign VGA_B = b_8;

```