The most important parameter of the projected image is its contrast.
Contrast of a picture is influenced by three factors:
- Projector - its light output, contrast, resolution and projection distance
- Screen - its size, reflectivity, flatness and material structure
- Room lightning - the amount of light, direction and degree of light passing through the window
ANSI (American National Standards Institute) and Infocom (currently AVIXA (AudioVisual and Integrated eXperiance Association) published a standard that specifies the optimal overall (system) contrast of the projected image for individual application. For the calculation purposes, the system contrast includes properties of a projector, projection screen, and room lighting.
|
Category |
Description |
Minimal contrast |
Examples |
|
passive tracking |
The viewer must be able to distinguish texts and images from the background of the image. |
7:1 |
basic image viewing, simple presentation |
|
basic decision making |
The viewer must be able to make basic decisions based on the projected image, they do not depend on the minor details. |
15:1 |
information displays, presentation with detailed pictures, school classes, meeting rooms, multi-purpose rooms. |
|
analytical decision making |
The viewer must be able to recognize all the details in the image. |
50:1 |
detailed drawings, diagrams, surveillance centers |
|
projected video |
The viewer is fully involved in the content of the projected image |
80:1 |
home cinema, viewing post-production video |