Traditionally Resene RGB values were measured from dry painted colour samples using sophisticated electronic colour scanning equipment. These RGB values were then converted to LAB and CYMK.
Resene is changing to using LAB values from our colour master samples as the base colour value. From these a RGB value can be mathematically calculated to achieve a given RGB value. That same LAB value can also be converted direct to CYMK and Hex values, reducing the number of conversions required to reach the desired colourspace. Colour accuracy is improved by starting with the largest colourspace then converting to the smaller colourspaces.
There are still limitations in the range of colours that can be shown in the RGB colourspace so some colours do not convert as well because they are out of gamut of the RGB colourspace. These differences are not faults in the conversion or software, but purely limitations of mapping dissimilar colourspaces to each other.
Because of these shifts in conversion, colours can be converted from LAB to RGB and CMYK, but when converted back they may result in different values due to the mapping process.
Mixing paint colours is called subtractive colour, so the colour you see is the colour that the paint does not absorb. For example yellow paint appears yellow because it absorbs all colours except yellow. Mixing light colours (e.g. RGB values) is called additive colour. This means that the object gives out (emits) colour, so that even if it is dark you can still see the colour. A television uses additive colour because it emits colour. Even if the room is completely dark if you turn the television on you can still see the television program. Due to these different colour systems and the limitations of the RGB colour system, the RGB colour system portrays some paint colours better than others.
Electronic colour is a superb tool for getting inspired and visualising the paint scheme prior to painting but must not be used as a substitute for the physical colours. In all cases Resene recommends that you view a physical sample of the colour, ideally by trialling with a Resene testpot where available, before making your final colour selection.
This is the only way to ensure that the colour will be accurate. Don’t settle for anything less.