Luminous emittance vs value recorded on image sensor

In summary, the gray level of the wall would be approximately 0.47 if the gray level of the bulb is set to 255.
  • #1
jamesdo
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Assume that I have a light bulb with luminous emittance of 160000lux (16ev), and a gray wall with luminous emittance of 300lux (7ev). I take the photo of this bulb and this background. Is there any approximate formula to estimate the gray level or RGB value of the bulb and the background in the image. In this case, I assume that the exposure is set for the light bulb (so the background should be very dark). Let's say the grayscale is 8 bits. If the gray level of the bulb is 255, what would be the gray level of the wall.

Thanks!
 
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  • #2
jamesdo said:
Assume that I have a light bulb with luminous emittance of 160000lux (16ev), and a gray wall with luminous emittance of 300lux (7ev). I take the photo of this bulb and this background. Is there any approximate formula to estimate the gray level or RGB value of the bulb and the background in the image. In this case, I assume that the exposure is set for the light bulb (so the background should be very dark). Let's say the grayscale is 8 bits. If the gray level of the bulb is 255, what would be the gray level of the wall.

Thanks!
The lamp and the wall have a ratio of emittance of 533. If you use an eight bit A to D conversion it can only handle a ratio up to 255.
 

1. What is luminous emittance and how does it differ from the value recorded on an image sensor?

Luminous emittance refers to the amount of light emitted from a surface or object, while the value recorded on an image sensor is a measurement of the amount of light that is captured by the sensor. In other words, luminous emittance is the source of light, while the value recorded on an image sensor is the result of that light being captured and converted into data.

2. How is luminous emittance measured?

Luminous emittance is typically measured in units of lumens per square meter (lm/m²) or lux (lx). A device called a lux meter is used to measure the amount of light in a specific area, and this measurement can be used to determine the luminous emittance of a surface or object.

3. What factors affect the value recorded on an image sensor?

The value recorded on an image sensor can be affected by a variety of factors, including the amount of light in the environment, the sensitivity of the sensor, and the shutter speed and aperture settings of the camera. Other factors such as the quality of the lens and the presence of any filters can also have an impact on the value recorded on the image sensor.

4. How does the value recorded on an image sensor relate to the image quality?

The value recorded on an image sensor is crucial in determining the image quality as it directly affects the amount of light and detail that is captured in the image. A higher value recorded on the image sensor typically results in a brighter and more detailed image, while a lower value can result in a darker and less detailed image.

5. How does the luminous emittance vs value recorded on an image sensor impact photography and imaging technology?

The understanding of luminous emittance and the value recorded on an image sensor is essential in photography and imaging technology as it allows for the proper adjustment of camera settings to capture the desired level of light and detail in an image. It also helps in understanding the limitations and capabilities of different cameras and sensors, enabling photographers and scientists to make informed decisions when selecting equipment for specific purposes.

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