AVTOP has provided this short FAQ to help customers understand some of the technical issues surrounding passive and active 3D systems for private use.
Question: Does active technology (shutter glasses) offer more resolution than passive 3D technology?
Answer: Currently, yes. In passive 3D technology, a polarizing filter (a Film‐type patterned retarder) in the display causes it to emit light using the interlaced technique (one field for the left eye and one for the right). The polarized glasses designed for this technology allow each eye to see only the correct half of the lines, whereby at typical viewing distances the image can appear to contain regularly spaced horizontal gaps, reminiscent of an old tube TV.
Q: Why do two fields in passive 3D technology not combine to give a frame with full HD resolution?
A: Picture errors become visible in each eye as a result of the black stripes mentioned above (the lines intended for the other eye), which correspond to the highest vertical resolution. In addition, the viewer is not able to overlay these finely structured images so that they complement one another. This structure only disappears when the viewer moves far enough away from the picture. At the necessary distance, however, the viewer is not able to perceive the highest‐resolution picture details.
Q: Do two 3D channels add up to give an image with higher resolution?
A: No. In practice, even under ideal conditions, the opposite is usually the case. 3D technology is significantly more susceptible to loss of resolution, as a result of its complexity and the additional elements involved in recording (e.g., beam splitters) and playback (glasses and filters in the display).
On top of this, there is the problem of the image being darker; with all currently available technologies, more than 50% of the brightness is lost in comparison to 2D. This causes a further reduction in the image’s subjectively perceived resolution.
Therefore, although current playback technology necessarily means some detail is lost, one might argue that the second perspective in the image introduces new picture information (albeit to a lesser extent). In strict terms, however, this has nothing to do with image resolution.
Q: Do the observed weaknesses in 3D operation also lead to poorer picture quality in 2D?
A: According to our tests, this is only the case with passive glasses technology. With some TVs with
passive 3D technology, we identified the following disadvantages in comparison to normal TVs:
‐ Limited viewing angle: Microlenses or frame patterned retarder layers limit the viewing angle.
‐ Detail reproduction: To reduce crosstalk, fine details are often filtered out of the image.
However, one major advantage of 3D TVs should not go unmentioned: Since the technical demands for good 3D are far more challenging than for good 2D, 3D TVs are frequently also more powerful in 2D operation — and, especially in terms of motion sharpness, are often better than devices that deal solely with 2D.
Q: What are 3D displays with 4K resolution needed for?
A: Currently, these are used primarily to combat the reduced resolution of passive systems (polarization or autostereoscopic). If you the number of lines doubles, you can halve them without fearing a loss of resolution in the picture. 3D sources in 4K resolution are therefore not necessary, following the introduction of 4K displays — formats such as Blu‐ray with MVC (that is, with two complete high‐definition 3D channels) deliver excellent results with displays of this kind.