In this section, we will publish our in-deep tests. Our users can learn what limitations are and potentially how to handle them. So that you know, we made tests based on randomly selected units only. 

It is worth remembering that no perfect instruments exist; each has limitations resulting from the adopted technical solutions. For specific applications, the same instrument may turn out to be unpredictable or be the best choice. There are no universal statements; however, some features can be observed quite repetitively.
An advanced user should understand that certain design features will affect the results - for such advanced users, we have conducted a number of tests in our laboratory, which are often time-consuming. Our articles show technical solutions and try to show how they affect the measurement results.
We analyze the measurement geometry, look at how it has been implemented in practice, and test the stability of measurements in standardized test conditions.
Our tests aim to show how to avoid situations where measurement errors will accumulate and how to standardize production measurement conditions better.

A few rules of a general nature

• The measuring geometry of the instrument must be matched to the type of sample to be measured. Matt uniform surfaces can be measured with almost any measuring geometry - however, in the case of structured and glossy surfaces, the decision must be preceded by tests. They are straightforward to make and don't take much time
  
  
• Measurement aperture size for non-homogeneous objects must include statistically reasonable repetitions to ensure repeatability. Therefore, small apertures cannot be used for low-frequency screen printing or heavy weave fabrics. The repeating pattern must be statistically averaged so that a slight dislocation of the instrument does not cause significantly different readings
  
  
• The illuminator built into the instrument determines the M-condition of the measurement. We need to assess what conditions are appropriate for our measurements and whether our object is sensitive to the phenomenon of fluorescence - that is, whether the UV component invisible to the eye will affect the color.
  
  
• A realistic approach to instruments makes us understand that whenever we mean standards - e.g., Illuminant D50 in the M1 measurement method - there will always be a difference between the theoretical D50 reference and the physically used light source - what can be used in practice is the D50 simulator which never it will 100% reconstruct the spectra of the Sun star. Consequently, technical solutions must compensate for the differences and somehow recalculate the results to represent the expected results better. What they will call compensation, optimization, or calibration, others may call manipulation. In reality, the data is recalculated - in practice, we get the result of complex algorithms, often using AI. Modern instruments don't have an objectively clean, raw output - what we get is the result of advanced engineering. Sometimes we deal with procedures in which manufacturers stretch the results of their measurements to imitate other competing solutions and sometimes also their own from the past.
  
  
• Most instruments are calibrated against a white calibration plate. The known parameters of the stable standard are then used to zero out [potential brightness differences - this is a one-point calibration. Some instruments offer black calibration - which increases precision.
  It should be remembered that light sources - nowadays most often LED - require temperature and supply voltage stabilization for repeatability. Very advanced measurement systems use complicated cooling systems; in other instruments, we find dedicated spectrophotometers compensating for the light source. Simple instruments can force an interval between measurements to cool...
  
  
• Some of the instruments on the market - especially the cheaper ones - are by definition, an engineering mixture of technological and financial compromises, it is easier to compensate for everything by increasing the price and keeping small dimensions. On the other hand, these truncated constructions allow to overcome limitations and enable measurements that were previously possible only in particular conditions.

Conclusion

Refrain from crossing out any solution on the market - learning their limitations, we can use them in tasks that seemed impossible or too expensive recently. By learning their nature, we can reduce potential errors and gain benefits. We encourage you to experiment - and draw conclusions. Standards have yet to cover many areas; even though they are there doesn't mean they are good. Hence the general conclusion - if we obtain repeatability and predictability, we can implement any method.

Basic test methodology

1. Short-term repeatability

In this test, we are taking a series of measurements - if possible, we are measuring instrument calibration tile, or if it is impossible white ceramic tile (Lucideon BCRA). The software should trigger all measurements to avoid micro-displacements so no operator can shake the instrument by triggering with a hardware button.

Additional tests can be taken on Gray and Black samples.