Hisense is preparing a firmware update for the PX4 Pro that adds a dynamic iris and a stronger rainbow-effect reduction mode, with October named as the target. The two headline features cannot be used at the same time. The changes were detailed this week by ProjectorScreen.com, which has the Q0917 build running on its review sample, and Hisense has said a comparable update is coming to the C3 series.
The dynamic iris is the larger change. Until now the PX4 Pro’s aperture has been fixed: seven manual positions plus two Cinema presets, chosen once and left there. The new mode moves the aperture according to the average picture level of the image and adjusts as scenes change. It defaults to off, and switching it on disables Scenario Enhancement, Brightness Enhancer and Laser Luminance Level adjustment, so it takes over the projector’s brightness controls rather than sitting alongside them.
The PX4 Pro went on sale in the United States in late July at $3,999.99, rated at 3,500 ANSI lumens and running VIDAA instead of Google TV. Its manual iris was measured position by position in ProjectorScreen’s August review, which makes it unusually easy to say what an automated version would be automating.
With the iris open, that HDR Theater sweep recorded about 2,088 compensated lumens and 3,021:1 native contrast. Manual 3 kept 83 percent of the light, at roughly 1,733 lumens, and reached 4,144:1. Manual 4 held 73.2 percent and 4,629:1. The last position, Manual 7, produced 4,873:1 while surrendering nearly half the output, down to about 1,079 lumens.
Run those numbers end to end and the curve has a clear shape. The first four steps deliver 87 percent of all the contrast the iris has to give, and cost 27 percent of the light. The remaining three steps buy the last 13 percent and cost another 450 lumens on top. That is exactly the shape that makes a moving aperture worth building: it can sit near the open end while a scene is bright and fall toward Manual 4 when the picture goes dark, instead of forcing the owner to pick one compromise in a menu and live with it through a whole film.
The same measurements carry a second point that has had less attention. No manual position reached the figure on the box. Hisense advertises up to 6,500:1 with the iris; the highest native contrast anywhere in that review was 5,545:1, from an earlier SDR sweep at iris 6 with output down around 1,313 lumens. A dynamic iris does not merely close the gap, it changes the test — full-field white and full-field black measured with the aperture free to move is a different measurement from a static one, and it is the standard way a number of that size becomes reachable without anything improving inside a single frame. Whether the published specification gets restated after October is worth watching.
The other addition is an RBE Reduction control aimed at the rainbow breakup that single-chip DLP produces for some viewers. Its labelling needs a footnote: Off keeps the baseline anti-rainbow behaviour the projector already had, and On selects a stronger mode. The stronger setting defaults to off and works in Filmmaker and Theater Night.
It also conflicts with the iris, Brightness Enhancer, Laser Luminance Level, the light sensor and energy-saving mode. In plain terms, stronger rainbow reduction and the new dynamic iris cannot run together.
That collision is not a corner case, because the two features are aimed at the same person. Someone who sees rainbows is most likely to see them on high-contrast material in a dark room, which is also the only condition under which a closed iris is worth its brightness penalty. The August review listed rainbow effect as noticeable to sensitive viewers and laser speckle as visible but heavily screen-dependent, and recommended that anyone sensitive to either audition the projector on the screen they intend to buy. Those owners now get two answers and a choice between them.
The on-screen description for the stronger setting warns that enabling it “increases noise from the device.” Nothing in the release notes says whether that means acoustic noise or image noise, and ProjectorScreen has said it intends to look closely at that when it tests the build.
The distinction matters more here than it would on most projectors. Running quieter than the PX3-Pro was one of the concrete gains reviewers credited to the PX4 Pro — roughly 2 dB by informal comparison, with a fan pitch that fades into a room rather than sitting on top of it. If the stronger rainbow mode spends that margin, the update hands owners a fix for one distraction by reintroducing another.
Hisense has not described how its implementation works. Valerion, the premium sub-brand of AWOL Vision, describes its own anti-RBE technology as raising the projector’s refresh rate and blending colour sequences with image processing fast enough that the eye cannot separate them. A mode built along those lines asks the light engine to do more work per frame, and more work means more heat to move. A warning about noise attached to a feature of that kind is at least consistent.
Valerion put its version across the existing lineup at CES on 6 January, free of charge, covering the Valerion Pro, Pro 2, StreamMaster Plus and StreamMaster Plus 2 alongside the flagship Max, and claiming to eliminate up to 99.99 percent of rainbow artefacts. It requires a two-part update, Android system firmware followed by DLP display engine firmware, and the company warns that doing only the first half leaves the feature switched off.
Since then, owner threads for other triple-laser models have spent the year asking their manufacturers the same question. What Hisense is doing is the version of this that counts: adding the control to hardware that already shipped, rather than holding it for next year’s model number. The C3 series is next in line, a line that began its global rollout this month at 4,000 and 5,000 lumens.
None of it moves the price. The PX4 Pro was selling on Amazon this week at $3,997.97 against a $4,497.97 list, which is where it started, and the machine reached Britain at last year’s PX3-Pro price while American buyers paid $500 more. This is a retention update, not a discount lever.
The question that decides whether it lands is not whether the dynamic iris beats Manual 4 on a test pattern. It almost certainly will, on paper. It is whether an aperture that moves with the picture stays invisible on an ultra short throw with a 0.2 throw ratio, firing up a wall from a few inches away into a room whose black floor is already set by everything the screen is bouncing light off. Irises that pump on cross-fades are an old complaint, and no specification sheet has ever predicted one. October is when that gets answered.