Pointillism is a style of art in which the image is created from many tiny dots of color. The technique was developed in the late 1880's as a branch of impressionism. It relies on the ability of the eye and mind to blend the myriad of tiny dots into a single cohesive image. While developed for painting, this technique is actually the way much of our modern technology works from TV's, computer monitors and even most printing systems. They all depend on the small dots of color (red, green, blue for TV type systems and cyan, magenta, yellow and black for printers) to form a full range of tones that make-up the images we see every day. The smaller the dots the more resolution a particular device has.
For more information about Pointillism check out these links:
Using Pointillism in photography is a little more difficult and comes down to either taking a picture of something that already has a pointillist nature such as a computer monitor, or doing something in post processing to mimic the pointillist painting style.
I decided to go the former route and create a macro image of a computer monitor screen while doing some testing of a lens with the Sony A7r (and a Canon 50 mm 3.5 macro lens). This image really shows the limitations of the JPEG compression and the sRGB colorspace. When reduced in size you can being to see lines or moire patterns that are not in the original image. These are a product of the computer downsizing the image on the fly based on your computer monitor and a slight smearing introduced by the JPEG compression. The image should be more colorful. The original image is about 5000 pixels square.
Here is what the a 1:1 crop the edge of the eye portion of the image so that you can see how the dots are structured.