What is RGBIR?
RGBIR stands for Red, Green, Blue, Infrared. It's a type of image sensor filter pattern that captures both visible light (RGB) and infrared (IR) light simultaneously.
In short: RGBIR sensors are ideal for outdoor/doorbell/security cameras where 24/7 performance is critical, especially in low-light or no-light conditions.
How It Works
Standard image sensors use a Bayer filter (red, green, blue) that blocks IR light to avoid color distortion.
An RGBIR sensor, on the other hand, includes an IR-sensitive pixel in place of one of the green pixels in each 2×2 group.
This allows the sensor to:
- Capture color images during the day
- Detect infrared light at night or in low-light scenes
Benefits of RGBIR for Outdoor & Doorbell Cameras
Improved Low-Light/Night Vision
- IR light (e.g., from IR LEDs) is invisible to humans but visible to IR-sensitive sensors.
- RGBIR sensors can use this light without needing a mechanical IR cut filter (like in standard cameras).
Simplified Design
- No need to mechanically switch between daytime (color) and nighttime (IR) modes.
- Reduces complexity, size, and potential mechanical failure.
Better Power Efficiency
- Lower power consumption due to simplified optics and sensor switching.
Facial Recognition in Darkness
- Some smart doorbell or surveillance systems use RGBIR sensors with IR LEDs for accurate face detection even at night.
Limitations
- Color accuracy may degrade slightly, since part of the green channel is replaced with IR detection.
- Lower resolution per color channel, because one pixel is dedicated to IR rather than RGB.
What is Lux in Imaging?
Lux is a unit of illuminance, which measures how much visible light hits a surface. In the context of image sensors and cameras:
1 lux = 1 lumen per square meter
In Camera Terms:Lux tells you how bright the environment is, and helps define how well a camera can perform in various lighting conditions.
| Light Condition | Approximate Lux Level |
| ------------------------ | --------------------- |
| Direct sunlight | 100,000 lux |
| Cloudy daylight | 1,000–10,000 lux |
| Office lighting | 300–500 lux |
| Twilight / street light | 10–20 lux |
| Full moon | 0.1–0.3 lux |
| Overcast night (no moon) | \~0.001 lux |
Why Lux Matters for Cameras
A camera's low-lux performance defines how well it can capture usable images in low-light environments (e.g., at night or in shadows).
A sensor rated at 0.01 lux can see in near-darkness.
A 0.001 lux camera may produce visible images even under starlight.
Example Use Case
If you're building a doorbell camera, it should ideally:
Detect faces and motion at <1 lux (nighttime with streetlight)
Possibly work with infrared (IR) at 0 lux (total darkness)
Summary
Lux = measurement of light level
Lower lux = darker scene
A "low-lux" sensor = can work well in low light
Essential for outdoor, night-vision, and surveillance applications
Let me know if you'd like a visual example comparing lux levels or how sensors behave in different lighting!
What Is Pixel Size in Image Sensors?
Pixel size refers to the physical dimensions of each individual pixel on an image sensor, usually measured in micrometers (µm or microns).
Example:
A 2 µm pixel is 2 micrometers wide.
A 3 µm pixel is 50% larger than a 2 µm one in both width and height — it collects 2.25× more area of light.
Why Pixel Size Matters
1. Low-Light Performance
Larger pixels = more surface area = more photons (light) captured
➡ Better image quality in dark scenes
| Pixel Size | Low-Light Sensitivity |
| ----------------- | --------------------- |
| Large (2.8–3 µm) | Very good |
| Medium (1.5–2 µm) | Moderate |
| Small (<1 µm) | Poor |
Noise Reduction
Bigger pixels have higher signal-to-noise ratio (SNR).
Less noise in shadows and dark regions.
Dynamic Range
Larger pixels can store more light (higher full well capacity).
Helps prevent blown-out highlights or black shadows in bright/dark mixed scenes.
Resolution vs Pixel Size Trade-off
To fit more pixels on a sensor (higher resolution), pixels must be smaller — which reduces low-light performance unless the sensor is physically larger.
| Sensor Type | Resolution | Pixel Size | Result |
| ----------- | ---------- | ---------- | ------------------------------------- |
| 1/3" 4MP | 2 µm | Small | Good detail, average night vision |
| 1/3" 4MP | 3 µm | Large | Lower resolution, better night vision |
Choosing the Right Pixel Size
| Use Case | Recommended Pixel Size |
| -------------------------- | ---------------------- |
| Daylight only | 1.1–2 µm |
| Indoor security | 2–2.9 µm |
| Outdoor/doorbell (low lux) | **2.9–3 µm or larger** |
Summary
Pixel size is a core factor in how well a camera performs in low light.
Larger pixels = better night vision, less noise, wider dynamic range
But: they often come with lower resolution or higher cost
What Is Dynamic Range in Image Sensors?
Dynamic Range (DR) is the range between the darkest and brightest parts of a scene that a sensor can capture at the same time without losing detail.
In Simple Terms:
Imagine you're trying to take a photo of someone standing in front of a bright window:
A low dynamic range camera will either:
Make the person look like a dark silhouette (loss of shadow detail), or
Overexpose the background (blown-out highlights)
A high dynamic range camera will:
Show both the person and the window clearly and correctly exposed
Why Dynamic Range Matters in Security & Doorbell Cameras
Scenes often include sunlight + shadows, especially outdoors
DR helps you see faces clearly even if backlit
Improves license plate readability in bright/dark conditions
What is HDR in Image Sensors?
HDR stands for High Dynamic Range. It’s a technique that enables cameras to see both very bright and very dark areas of a scene at the same time — without losing detail.
Why It Matters:
In real-world scenes (e.g., outdoors), lighting can vary drastically:
Bright areas (like sunlight)
Dark areas (shadows or inside doorways)
Without HDR, cameras often:
Blow out the highlights (too bright)
Or crush the shadows (too dark)
How HDR Works in Sensors:
| Technique | Description |
| ------------------------------ | ------------------------------------------------------------------------------ |
| **Multiple Exposure HDR** | Takes 2–3 exposures (short + long), merges into one image. |
| **DCG (Dual Conversion Gain)** | Switches between high and low gain in real time for better dynamic range. |
| **Line-based HDR** | Captures alternating short/long exposures line by line on the sensor. |
| **Digital Merge** | Uses ISP (image signal processor) to blend highlights and shadows in software. |
HDR Benefits for Doorbell/Outdoor Cameras:
Face detection in backlit scenes
Read license plates at night with headlights
No “washed out” skies or “blacked out” shadows
What is Mono Mode (Monochrome Mode)?
Mono mode disables color processing and uses the sensor in black-and-white mode.
Why Use Mono Mode?
| Benefit | Explanation |
| ----------------------------- | ------------------------------------------------- |
| **Better sensitivity** | No Bayer filter, so all light reaches the pixel. |
| **Sharper detail** | No interpolation or color processing. |
| **Great for IR/Night Vision** | Monochrome sensors capture infrared light better. |
Color Sensor in Mono Mode:
Some color sensors can switch to mono mode in low light (especially with RGBIR sensors). This improves night vision by:
Ignoring color info (less noise)
Using IR light from LEDs for visibility in total darkness
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