One of the qualities of natural brick is the richness offered by the slight colour variations that are in the clay or other material from which bricks were made, how the bricks reacted to the baking or curing process, how they have aged, and in the case of used brick, how they have been recycled. This colour diversity can make it hard to pick one colour choice for paint as an exact match for a brick surface and often a colour scheme that beautifies the overall look with either lighter or darker shades and tints or well-explored colour combinations might be the best option.
Gather paint colour chip strips from the racks at the paint store that you think could be a match for the colours in your brick. Borrowing or purchasing a complete colour fan from the paint store can make the process of matching easier.
Take the colour chip strips or colour fan home and visually match the closest colour chip to the colours in the brick.
If you have an extra brick with the colours you want to match, reverse the process and take it to the paint store and match to the closest chip set or fan while there.
Scan the brick with a hand-held scanner, such as those offered by some major paint retailers, as an alternative to matching colour by eye. Both Benjamin Moore and Sherwin Williams offer smartphone technology in the form of free applications. The scanner returns the closest paint chip code and name to match the colour scanned.
Take a close-up photo of the brick with a digital camera. Load the image to a computer with a colour-corrected monitor and adjust colour if necessary.
Use a free or commercial pixel-grabbing program (set to RGB capture) to get the colour of any pixel in your image. Most graphics, illustration, paint and colour programs have them built in.
Input the RGB code into a free program that allows you to select colour collections from most major paint companies and returns the closest paint matches along with their names and colour codes. Most major paint company websites also have capabilities to convert RGB codes to paint colours in their collections.
Input the colour code into any number of free or inexpensive colour scheme and exploration programs that let you experiment with different shades and tints of colour and try out different colour schemes to see how they go together and might fit with other aspects of your exterior like landscaping.
Virtual painting programs are available on most all the major paint manufacturers' websites and give you an overview of what colour schemes you pick will look on similar houses or on your own if you upload a photo and mask off the different areas. Most also suggest possible colour schemes based on your starting colour selection, colour theory and current colour trends.
Many paint manufacturers offer small sample bottles or pouches of paint in many colours to try committing to quarts and gallons.