In the projector daily use, the projector position wants as far as possible and projects large screen to have the right angle to be able to guarantee the projection effect (like the picture).
Looked from the side
Looked from above
If is unable to guarantee two vertical, the picture can have the trapezoid. In this kind of situation, the user needs to use "the trapezoid adjustment function" to adjust the trapezoid, guaranteed the picture becomes the standard the rectangle.
The trapezoid adjusts usually has two methods: Optics trapezoid adjustment and the digital trapezoid adjust, optics trapezoid adjustment is refers through adjusts the lens the physical location to achieve the adjustment trapezoid the goal, another kind of digital trapezoid adjustment is realizes the trapezoid through the software method to adjust, the nearly all projector manufacturer all has used at present the digital trapezoid adjustment technology, moreover uses the overwhelming majority projector which the digital trapezoid adjusts all to support the vertical trapezoid adjustment function, namely the projector may adjust own altitude in the vertical direction, from this trapezoid which produces, carries on the vertical direction through the projector the trapezoid adjustment, then causes the picture to become the rectangle, thus has facilitated user's use. But in the practical application, besides needs to be vertical the trapezoid adjustment, but also the frequently bias produces the trapezoid, this brings inconveniently for some users' uses. For example in the classroom, The projector in order to vertical places with the screen, can affect student's line of sight. If the projector has the horizontal trapezoid adjustment function, is not may solve this problem? In view of this kind of situation, many projector manufacturers all are researching and developing "the horizontal trapezoid adjustment function".
The horizontal trapezoid adjustment and the vertical trapezoid adjust all belongs to the digital trapezoid to adjust, all is through the software interpolation algorithm to demonstrated before the picture carries on the shape control and compensates. The horizontal trapezoid adjustment has solved because the projector lens and the screen are unable the horizontal direction picture keystone distortion which is vertical produces, thus enables the projector to be allowed in screen side also to be allowed the similar realization standard rectangle projection picture. Now, again returns to in the classroom which mentioned a moment ago, we may move the projector side, student's line of sight no longer is affected.
At present, Epson, Sony, Panasonic, NEC etc the world famous manufacturer uses this technical in the development development the product. But therefore the technical principle has its limitation, inevitably has the influence in the use to the picture quality.
The digital trapezoid adjusts regarding to the picture precision request not high application, may the very good solution keystone distortion question, the usability be extremely strong, but requests a higher application regarding these to the picture precision not really to be suitable. This is because, The picture after the adjustment, picture some lines and the character edge can appear the burr and not the smooth phenomenon, causes the clarity is not very ideal. At present, in view of this question, the projector merchant is conducting the thorough research, seeks in the technology solution, believed the new breakthrough and pleasantly surprised cannot too be far.