For high-quality viewing of a movie in a completely dark room (even without preparing the room to eliminate reflections), the minimum illumination of 1 square meter of the surface of a matte white screen with a gain of 1 is required in the region of 100-120 lux, no more. Thus, a typical 120" screen (approximately 4 sq.m.) requires about (100-120) x 4 - 400-500 lumens. This is how good cinema projectors usually shine in cinema modes with hardware filters. With on / off contrast not less than 2000:1 (better than 6000:1), which is provided only by fairly expensive models.Moreover, the absurdity of the situation in cheap projectors is that, on the contrary, they set a monstrous brightness of 1500-3000 lumens, while disabling the capabilities of hardware cinema filters on the above 400-600 lumens. They simply cannot be obtained without hanging filters on the ND2-4 lens yourself. Although it is they (cheap models) who need it in the first place. At the same time, cheap models are also completely inconvenient for installation in residential premises (and cheap models bought by poor people who are usually cramped in living conditions) - they do not have a normal lens shift of -50 / + 50% vertically and horizontally, which is the minimum necessary when suspended on a short rod from the ceiling so that the projector does not interfere with living room and hanging the screen, for example, above the window.
Therefore, cheap projectors are not in demand. And the expensive ones have become meaningless today - Hollywood is practically dead. R.I.P.
World sales of projectors do not exceed 8-10 million per year, which is an order of magnitude less than sales of TV and everything else. Despite the fact that watching a movie on something other than a projector and a diagonal of less than 105-120 "- in fact, do not watch a movie. As well as high-quality multi-channel sound. And 4k projectors (with real 4k matrices) are still monstrously expensive, especially with high-quality optics (even Sony has plastic and not very sharp optics in younger models priced at $6k+, which reduces 4k resolution to 2.5-3k in practice).
We are more likely to wait for OLED TVs rolled into a tube (like projector screens) with 100"+ diagonals than to see cheap 4k projectors with all the necessary technologies and the comfort of installation in residential areas for those who are cramped in space.
150 lumens, it seems kind of pointless to waste hardware on this device. Even cheap toy projectors have more brightness. It would ony be visible in the darkest room, and even then not very bright. I suspect that value is incorrect.
The Xiaomi Redmi Projector and Redmi Projector Pro are now available to pre-order in China. The gadgets have a 1080p resolution and up to 150 ANSI lumens brightness. The Pro has more advanced automated image correction tools than the standard model, including autofocus and obstacle avoidance.