An RGB signal carries visual information as three separate color channels (red, green, and blue) that combine to produce a full spectrum of colors on a screen. Each channel transmits its own intensity level independently, and your display blends them together at every pixel to create the image you see. This approach, called additive color mixing, starts from black and adds light: combine all three channels at full intensity and you get white, turn them all off and you get black, and every other color is some mix in between.
How Additive Color Mixing Works
Your screen is made up of millions of tiny sub-pixels, each one red, green, or blue. An electrical charge causes each sub-pixel to glow at a specific brightness. Three adjacent sub-pixels (one of each color) form a single pixel, and by varying their individual brightness levels, that pixel can appear as virtually any color. A pixel with the red and green sub-pixels at full brightness and blue turned off looks yellow. Red and blue together produce magenta. All three at equal low intensity produce gray.
This is fundamentally different from how ink or paint works. Paints use subtractive color mixing, where adding more pigment absorbs more light and makes things darker. RGB signals do the opposite: adding more light makes things brighter. That’s why RGB is the native language of anything that emits light, from TVs and monitors to phone screens and LED panels.
Analog RGB Signal Levels
In an analog RGB signal, each color channel is a continuously varying voltage. The standard peak level for each channel is roughly 700 millivolts across a 75-ohm load. At 0 volts, that channel is completely off. At 700 mV, it’s at full brightness. Everything in between represents a shade of that color. So the signal is literally a voltage waveform that the display reads moment by moment, line by line, to paint an image on screen.
This is why analog RGB was long considered the gold standard for retro gaming and classic video equipment. Each color travels on its own wire with its own voltage, so there’s no need for the display to decode or separate colors from a mixed signal (as it would with composite video, where everything is crammed onto a single wire). The result is a sharper, cleaner image with more accurate color.
Sync Signals: Telling the Display Where to Draw
Color data alone isn’t enough. The display also needs timing information so it knows where each line starts and where each frame begins. This timing data is called the sync signal, and RGB systems handle it in several ways.
- Separate sync (RGBHV): Two dedicated wires carry horizontal and vertical sync pulses independently. This is the method VGA connectors use and is common in computer monitors.
- Composite sync (CSync): The horizontal and vertical timing pulses are combined into a single sync signal on one wire. A pure composite sync signal, stripped of any video data, provides the cleanest timing reference and avoids image jitter.
- Sync on green (RGsB): The sync information is embedded directly into the green channel’s voltage, eliminating the need for a separate sync wire entirely. Some professional video monitors and certain game consoles use this format.
A common but less ideal approach is pulling sync from a composite video signal, which carries color and brightness data on top of the sync pulses. This works, but the extra data riding on the signal can introduce slight jitter or instability compared to a clean composite sync.
Common Connectors That Carry RGB
Several physical connectors have been used to transmit RGB signals over the years. The VGA connector, a 15-pin D-sub plug familiar from decades of computer monitors, dedicates pins 1, 2, and 3 to red, green, and blue respectively, with separate return (ground) pins for each color channel and additional pins for horizontal and vertical sync. SCART, the chunky rectangular connector common on European televisions, also carries RGB on dedicated pins, with pin 15 for red, pin 11 for green, and pin 7 for blue.
BNC connectors, often used in professional and broadcast settings, typically run each color channel and each sync signal on its own separate cable, giving you four or five individual BNC plugs for a single RGB connection. This approach offers the best signal isolation but takes up more space. In the modern digital world, HDMI and DisplayPort both carry RGB data, just in digital form rather than as analog voltages.
Color Depth: How Many Colors RGB Can Represent
The number of possible colors in an RGB signal depends on how many bits are used to represent each channel. In the most common setup, each channel gets 8 bits, meaning each one can express 256 brightness levels (0 to 255). Multiply 256 × 256 × 256 across the three channels and you get roughly 16.7 million possible colors. This is what “24-bit color” or “true color” refers to.
Higher bit depths push that number dramatically. At 10 bits per channel (30-bit color, often called “deep color”), each channel has 1,024 levels, producing over 1 billion possible colors. At 12 bits per channel, the total jumps to over 68 billion. The practical benefit of deeper color is smoother gradients. In scenes with subtle shifts, like a sunset or a shadowed wall, 8-bit color can show visible banding where one shade steps abruptly to the next. Ten-bit color largely eliminates that.
RGB vs. Component Video (YPbPr)
RGB isn’t the only way to transmit color information. Component video, labeled YPbPr on the back of many TVs, takes the same underlying color data and reorganizes it. Instead of sending red, green, and blue directly, it sends one channel for brightness (Y) and two channels for color difference information (Pb and Pr). The brightness channel is actually a weighted mix of all three RGB values, with green contributing the most (about 59%), red contributing 30%, and blue about 11%, reflecting how the human eye is most sensitive to green.
This reorganization was originally designed to be compatible with black-and-white television (which only needed the brightness channel) and to allow more efficient bandwidth use. The color information can be compressed more aggressively than brightness without the viewer noticing, which is why formats like YCbCr 4:2:2 exist in the digital world. They reduce the resolution of color data while keeping full brightness detail. For the sharpest possible image, especially with text or fine graphic detail, full RGB (equivalent to 4:4:4 color sampling) preserves every bit of color information at every pixel. That’s why PC monitors default to RGB, and why gaming setups benefit from selecting RGB output when the option is available.
RGB Color Spaces: sRGB and Adobe RGB
Not all RGB signals describe the same range of colors. A color space defines exactly which shades of red, green, and blue are used as the “anchor points” and therefore how wide the overall palette is. The two most common are sRGB and Adobe RGB.
sRGB was developed in 1996 by Microsoft and HP as a universal standard. It covers about 97% of the colors most cameras capture and most displays can show, making it the default for web content, consumer cameras, and the vast majority of screens. If you’re viewing something on a phone, laptop, or standard monitor, you’re almost certainly looking at sRGB content on an sRGB display.
Adobe RGB, introduced in 1998, covers a roughly 35% larger range of colors, particularly in the cyan and green areas. It was designed to better match the output range of professional printing presses. The catch is that a standard sRGB monitor can only display about 76% of the Adobe RGB palette. You need a specialized wide-gamut monitor (from brands like Eizo or BenQ’s photography lines) to actually see the difference. For photographers and print professionals, shooting and editing in Adobe RGB preserves more color detail for the final print. For everyone else, sRGB is the practical standard.
Digital RGB and Display Processing
Modern digital connections like HDMI and DisplayPort transmit RGB data as streams of binary values rather than analog voltages, eliminating the noise and signal degradation that analog cables can introduce. Your graphics card or media player encodes each pixel’s red, green, and blue values as numbers, sends them digitally, and the display’s controller converts those numbers into the voltages that drive each sub-pixel.
One practical consideration with digital displays is processing latency. When a signal arrives at a modern TV or monitor, the display’s internal processor may scale, sharpen, or color-correct the image before showing it. This adds a small delay between when the signal is sent and when you see the result. CRT monitors had essentially zero processing delay because they drew the RGB signal directly to the screen as it arrived. Modern displays in “game mode” try to minimize this processing to keep lag low, which matters for competitive gaming or any application where responsiveness is critical.