Blueline is a blue photographic proof used to check the placement of all image elements.
Blueline paper is a brand of photographic paper used for technical drawings such as blueprints. This thin sheet is coated with light-sensitive chemicals, which cause its surface to turn blue when exposed to sunlight.
Contact printing utilizes paper as part of its process, with negative or positive images placed over it and exposed to light, where exposed areas turn blue while those not exposed remain white.
Blue lines in photography refer to films or papers used for blueprinting purposes. A blue line acts as an inverted negative of its subject image, used to create positive copies on white paper – this process is known as blueprinting.
Blue lines can be created by first exposing film or paper to light; contact printing can be done by placing the negative directly against the paper and underneath it. After development, any exposed areas turn blue; the darker your original image, the deeper the blue line created from this process.
Once a blue line has been drawn, it can produce a positive copy by shining light through its negative and onto paper, where exposed areas will turn white while non-exposed ones remain blue.
Blueprinting is an integral component of construction projects, enabling architects and engineers to produce accurate plans of buildings. Blueprinting can also be used to create replicas of paintings or images.
Digital photography made creating images more manageable. Still, many prefer Blueline photography for its greater control and quality prints. This technique produces prints far superior to those created with digital technology while providing photographers more freedom to create images that cannot be duplicated.