1Projection and imaging systems

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

Examples of projection distances

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.

Overview of recommended contrast values ​​for individual applications
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