The Vivitek DH3660Z claims an exceedingly bright 4,500 lumens. This projector did fall short of its claim, but only just, with its brightest mode, Bright, coming in at 4,269 lumens. Most projectors fall short of their manufacturer claims, some even by 25%, but the Bright mode on this projector came pretty close. 4,269 is plenty bright to handle even the most dire of ambient light circumstances.
You won’t be using Bright Mode, however, because it is ugly. If you have uncontrollable ambient light, but still want pretty decent color, you’ll want to go with Presentation or User Mod. Presentation Mode measured at 3,467 lumens, and User measured 3,113. Movie Mode, the best mode for video content, measured a nicely bright 3,042 lumens. Game Mode follows as the next brightest, at 2,571 lumens, and DICOM SIM. after, at 2,028 lumens.