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In our previous blog we talked about which decisions you have to make when choosing which camera you need for your application. However for each type of camera, defined by interface, resolution, frame rate, reliability tests etc., there are often several manufacturers to choose from. So how should you determine your final manufacturer choice?
The best way to obtain arguments for your choice is by evaluating cameras with special focus on the image quality.
There are a few general known methods to evaluate image quality and we will briefly mention them in this blog. However it is always important to put your application on the first place. Always ask yourself if the general method of image quality evaluation is also useful in your case. Don’t be afraid to deviate from the standard method if you think it does not lead to the right decision.
Photon transfer curve
A photon transfer curve is basically a measurement where you measure the gray level of the camera at varying light intensity, e.g. photon numbers. This is a very useful measurement as it gives you information about a variety of image quality related specifications: readout noise, conversion gain, saturation level and linearity of the sensor response.
For more information read our earlier blog post:
How to measure the Photon Transfer Curve for CCD or CMOS cameras
Evaluating Machine Vision Cameras versus Comparing Camera Specification Documents
EMVA 1288
The EMVA 1288 standard is specially designed to make comparison of cameras from different manufacturers easy. It basically gives a protocol of which specifications to measure and how to measure them. This includes a photon transfer curve measurement.
For more information read our earlier blog post:
Does the EMVA 1288 Standard help you decide on the right machine vision camera for your application
Modulation transfer function
In some cases the photon transfer curve might not give you the most important information for your application. It might be that in your application the modulation transfer function is more important. In our earlier blog you can read that the MTF is determined by the combination of lens and camera:
Why the Modulation Transfer Function MTF also matters with camera selection especially in NIR
As the mechanical interface of the camera determines in large part the accuracy to which the lens is aligned to the center of the sensor (read more about it in our previous blog), the MTF can be different between manufacturers even if the same sensor technology is used.
If you want to read more about sensor comparison, please read our e-paper about this topic. You can download it here:
