What Trapezoid Correction of Projector Is

05.06.2020 0 iCODIS Official

We often see “trapezoid correction” when we buy projectors, so what exactly does trapezoid correction mean?

What is trapezoidal correction?

Trapezoidal distortion occurs when the projector is not vertically aligned with the screen or when the projection screen has an inclined surface.

What is trapezoidal correction

Early projectors did not have trapezoid correction. Projector is usually in a fixed position, which greatly limited the placement of furniture. As projectors become lighter and more portable, the demand for simpler projector solutions is also growing.

Why to use trapezoidal correction

Why to use trapezoidal correction

If you want the projector to project a normal picture, it is better to form a relatively vertical position with the projected object. However, in the actual operating environment, due to hoisting restrictions and site restrictions, it is completely impossible to achieve a perfect projection angle. Therefore, trapezoidal correction function came into being.

Characteristics of trapezoid correction

At present, high-end projectors in the market have been basically equipped with trapezoidal correction function. Generally speaking, trapezoidal correction is basically divided into two types: optical trapezoidal correction and digital trapezoidal correction. At present, most projector products basically adopt digital trapezoidal correction. This trapezoidal correction method supports vertical trapezoidal correction function, i.e. the projector can adjust its height in the vertical direction. The resulting trapezoid can make the picture rectangular through vertical trapezoidal correction by the projector, thus facilitating users' use.

In addition to vertical trapezoid correction, many manufacturers have also developed horizontal trapezoid correction technology, which is the same as vertical trapezoid correction. Horizontal trapezoid correction technology also belongs to digital trapezoid correction technology. Generally speaking, software is used to correct images to avoid distortion of horizontal images.

trapezoid correction demo

Two trapezoid correction methods

Today, two trapezoidal correction methods have evolved, manual trapezoidal correction and digital trapezoidal correction.

Manual trapezoidal correction is basically the physical adjustment of the projector lens to project at a higher or lower angle than on a flat surface. Manual adjustment works well in some cases, but it cannot eliminate horizontal keystone distortion. The projector also needs to be far away from the screen to achieve the effect.

Digital trapezoidal correction

LCD and DLP projectors are both digital display devices. Some new projectors can change the angle of the image before it reaches the projection lens, which makes the final projected picture rectangular in any case. This makes it more flexible to set up projectors in a variable environment.


Different projectors can provide different amounts of trapezoidal distortion correction. For vertical (up and down) ones, some projections provide a correction of 12 degrees while others provide a correction of up to 45 degrees.

It can be said that all projection products on the market have set up trapezoidal correction function, and some have even introduced automatic trapezoidal correction according to the algorithm, thus greatly improving the use experience of projectors.

Trapezoidal correction is a necessary function in the daily use of projectors. Most of the projectors that need this function are mini-projector products, because this kind of products have great flexibility and different placement positions. Trapezoidal correction technology can be used to avoid distortion and has strong practicability.


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