The contrast ratio
Just as important as the achievable brightness is the contrast ratio. This describes the ratio between the brightest and darkest point that can be displayed in the greyscale. The limits are determined by the technology. With a low contrast ratio, for example, black can't be displayed – there is always a grey haze over the image.
Projectors usually achieve a contrast ratio of more than 500 to 1, although this range can hardly be fully used as long as there is ambient light. To display black you need darkness, because black isn't projected – it results from blocking the light to the screen.
Due to their design, projectors with DLP mirror technology often have a higher contrast ratio than LCD devices. However, this drawback is offset by newly developed LCD panels and the additional use of irises and intelligent light control.
Understanding contrast specs: on/off, in-picture and ANSI contrast
On/off contrast is listed in the technical data of every projector. It defines the ratio of the darkest to the brightest signal level: if a projector with a light output of 800 ANSI lumens still projects two ANSI lumens of residual light when displaying black, the contrast is 800:2, i.e. 400:1.
In-picture contrast, by contrast, describes the difference in brightness possible within a single image – due to stray light in the device and the room, it is always considerably lower than the on/off value. ANSI contrast is the official measurement method for this: it is measured with a chessboard pattern, comparing the brightness of all the black squares with the brightness of all the white squares. For the picture you actually see in your living room, this in-picture contrast is often more meaningful than the big on/off figure on the data sheet.
back to projector technology and terms
Matching product categories in the shop:
Further guides:
- Projector buying guide using the BEAM method – overview of all guides
- Projector brightness – rule of thumb: ANSI lumens per square metre
- How many lumens does a projector really need? A practical guide for every scenario – ANSI lumens per scenario, with real-world values
