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EMVA 1288 Overview: Imaging Performance 


Throughout the FLIR website, we make references to certain terms and specifications that relate to the imaging performance of a camera. This page provides a simple and straightforward description to these specifications. 



Other Helpful Resources for Choosing a Camera:

What specifications are tested and what do they mean?

right blue arrowQUANTUM EFFICIENCY (abbreviated as QE)

2 Examples of Quantum Efficiency

Unit of measurement: Percent (%)

Definition: The percent of photons converted to electrons at a particular wavelength by the sensor.

What does this really mean? A sensor with a high quantum efficiency means the sensor is more efficient at turning incoming light to an electrical signal. A higher QE means a greater sensitivity for detecting light; this is particularly beneficial to most applications but is especially beneficial in low-light applications. In addition, certain sensors may be geared towards better sensitivity at different wavelength ranges. Depending on your application certain QE results at certain wavelengths might be more important than others. For example, higher QE in the near-IR range (850 - 950nm) is important in low-light traffic monitoring. Some of the best sensors FLIR offers have a peak QE of 70%-80% (refer to image for chart example). No sensor is 100% efficient.

What affects the results? Results are inherent of a manufacturer's sensor design. Newer sensors, such as Sony Pregius sensors, tend to have higher QE.

 

right blue arrowTEMPORAL DARK NOISE (also known as Read Noise)

Example of how Temporal Dark Noise impacts an image

Unit of measurement: Electrons (e-)

Definition: Noise in the sensor when there is no signal.

What does this really mean? Lower temporal dark noise means a cleaner image. All sensors exhibit some level of temporal dark noise. Temporal dark noise is caused by the electronics on the sensor. Temporal dark noise is not affected by exposure time. Note that temporal dark noise does not include shot noise.

What affects the results? Results are inherent to both sensor and camera manufacturer's design. Newer sensors take advantage of techniques to lower temporal dark noise. Camera manufacturers can futher reduce noise through lowering the pixel clock and turning off certain electronics around the sensor such as FLIR's low noise imaging mode.

 

right blue arrowSATURATION CAPACITY (also known as Full Well Depth)

Saturation Capacity of Sensors

Unit of measurement: Electrons (e-)

Definition: Amount of charge that a pixel can hold.

What does this really mean? Each pixel is like a well or bucket that can hold electrons. Saturation capacity shows the maximum number of electrons that an individual pixel can store and is, in general, related to a sensor's pixel size. The higher the saturation capacity the higher the potential dynamic range. The lower the number the faster the pixel will reach maximum charge. If you imagine all the pixels reaching saturation capacity it would basically show as a white screen on your monitor. Saturation capacity on its own isn't a perfect metric to base sensor performance on because temporal dark noise and quantum efficiency work in relation to it for dynamic range and signal to noise ratio results.

What affects the results? Results are inherent to the manufacturer's sensor design. Newer sensors with improved pixel designs will have higher saturation capacity results. In general though, the larger the pixel size the more likely the saturation capacity will be higher.

 

right blue arrowSIGNAL TO NOISE RATIO (abbreviated as SNR or SN)

Signal to Noise Ratio for Camera sensors

Unit of measurement: Decibels (dB) or Bits

Definition:Ratio between the signal at saturation versus the noise at saturation. Noise at saturation is predominantly shot noise.

What does this really mean? The higher the number the more contrast and clarity you'll have in the image in relation to the noise in the image. For example, if you have a SNR of 1, the object you're imaging will be indiscernible to the noise in the image. A high signal to noise ratio is an important specification for very low light applications such as darkfield microscopy and fluorescence imaging. All sensors in the FLIR camera portfolio have a SNR above 35 dB with the best achieving results higher than 40 dB.

What affects the results? Results are inherent to both sensor and camera manufacturer's design. Temporal dark noise, shot noise, quantum efficiency and saturation capacity results will affect the ratio.

 

right blue arrowDYNAMIC RANGE

Signal to Noise Ratio for Camera sensors

Unit of measurement: Decibels (dB) or Bits

Definition:Ratio between the signal at saturation versus the minimum signal the sensor can measure.

What does this really mean? The higher the number the more levels of grayscale detail you'll achieve in the image. In other words, dynamic range describes the camera's ability to detect the maximum and minimum of light intensities (shadows and highlights). Models with higher dynamic range can detect more detail in the darks and lights. Outdoor applications such as surveillance, where both very bright and dark areas are being imaged at the same time, or autonomous vehicles, in which cameras are exposed to rapidly changing lighting conditions, will benefit from a higher dynamic range as they are more able to gather useful data in very bright and very dark scenes.

What affects the results? Results are inherent to both sensor and camera manufacturer's design. Temporal dark noise, quantum efficiency and saturation capacity results will affect the ratio. The camera's Analog to Digital Converter (ADC) can also affect the dynamic range as a lower bit ADC could cap the maximum dynamic range.

 

right blue arrowABSOLUTE SENSITIVITY THRESHOLD

Absolute Sensitivity Threshold for Camera Sensors

Unit of measurement: Photon (γ)

Definition: Number of photons needed to have signal equal to noise.

What does this really mean? The lower the number the better the camera can detect useful imaging data out from the noise of the camera. This specification is more important for applications in very low light situations. Unlike looking at just QE or temporal dark noise, absolute sensitivity threshold gives a better understanding of low light performance because it already takes into account the QE and temporal dark noise of the sensor along with shot noise.

What affects the results? Results are inherent to both sensor and camera manufacturer's design. Absolute sensitivity threshold takes into account both temporal dark noise, shot noise and the quantum efficiency of the sensor.

 

right blue arrowGAIN

Absolute Sensitivity Threshold for Camera Sensors

Unit of measurement: Electrons over 16 bit ADU (e-/ADU)

Definition: Parameter indicating how big a change in electrons is needed to observe a change in 16bit ADUs (better known as grey scale)

What does this really mean? To understand this specification better, imagine a 16 bit grey scale chart. 16 bits of grey equals 65,535 unique levels of grey (refer to image). In order for the sensor to register a jump to the next grey level you would need a specific number of electrons. This is what this specification describes.

What affects the results? Results are inherent to sensor and camera manufacturer's design. Saturation capacity and the specified ADU (in this case, we use 16 bit) will change the results.




  Where can I find camera sensor results?  




Imaging Performance Specification PDF

For detailed EMVA 1288 performance results with QE curves please download the Imaging Performance Specification PDFs located under the "Documents" tab of each model.
Camera Sensor Review

Camera Sensor Review ThumbnailFor a side-by-side comparison of our USB 3.1 and GigE models download our Sensor Review PDFs here. Note: These PDFs do not include our QE charts.
 




  Additional Resources  

 

Video: Why is the EMVA 1288 standard important?

Video: How a sensor works & what performance points are measured

White Paper & Video: How to Evaluate Camera Sensitivity

How to evaluate camera sensitivity white paper and video link


For detailed information on the EMVA 1288 Standard visit the EMVA 1228 website.

Download EMVA 1288 Official and Release Candidate documentation .