Colour printing is the best way to make your own photos from a picture you have taken with your digital camera. It is also a great way to print your business correspondence such as charts, graphs, brochures, and cards.
The process by which printing for commercial purposes is called four colour process printing. This is because four colors of ink are used. The three primary colours are cyan, magenta, and yellow as well as black. There are two techniques that are used to accomplish four colour printing. The pre-press stage is used when original images are converted to a form by using colour separation and screening to allow them to be used on a printing press.
By using this process the printing plates can transfer colour impressions onto paper on the printing presses using lithography. Another method is also becoming more frequently used. Six colour process printing adds two more colours to the original four. Orange and green are the two added colours for a wider range of printing. These systems will still use color separation to get the printed images desired.
There are also color printing processes that can only use one colour ink as well as many colours that are not primary colours. The use of a number of colour inks that are not primary colours is called spot colour printing. These inks are usually a special formula that is not supposed to be mixed with other colors of ink to achieve the shade you need. There are many colours that are possible using this method.
Spot colour can be inks that are from very pale colours to a fluorescent or metallic colour. Before the advent of digital imaging the main way of doing this was to take a picture of the image you were printing three times. A filter had to be used each time.
When this was done you had each of these images to change the optical configuration. The three main colours used to reproduce the printed picture are cyan, magenta, and yellow. By combining these three colours, the printed picture should be a reproduction of the one being used. However, this is not what happens. Because of the limited abilities of the ink pigments the colours do not look like the image being used. This is where the black comes in. It is used to improve the image. The shadow and contrast are much improved by using black ink. There are many methods that are used to obtain the black separation that is needed for the image you are printing. These techniques may include:
Grey component replacement
Under color removal
Under color addition
When this is used it is called CMYK. For optimal reproductions of the image you want to copy this must be used to ensure the colours look professional and true.