These colour samples are taken from various web sites, or by analysing colour charts. However, they may not be accurate and your monitor may not display the colour accurately, and room lighting can make a big difference to the appearance. So any decision on colour needs to be carefully checked when buying paint.
Cross reference tables:
Railway colours were scanned in CIE Lab using a Datacolor spectrocolorimeter from "Britain's Railway Liveries" by Ernest Carter, "Great Western Way", and "Railway Liveries" by Brian Haresnape. Munsell colours in "HMRS Livery Register No 3 LSWR and Southern" were converted to CIE Lab by software. Most BSI and RAL colours were scanned in CIE Lab from paint colour charts, those with * were converted from information on the Internet. The Model Master colours are scanned from the chart in their Terchnical Guide, however these samples are a little small which may affect the accuracy. Other paint colours are less accurate and taken from lower quality printed charts or converted from RGB values on web sites. The Games Workshop colours on their website are not very accurate, 3 colours use the same sample image, and some are scanned from actual paint samples.