In theory it shouldn’t. Pixel shifting is done at 240Hz. You still get 60Hz at 1080p.
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Just to be clear, this isn’t Philips technology. It comes straight from Texas Instruments. The entire array is mounted on a quadrature voice coil and shifted half a pixel in each direction while it draws 4x the frame rate. That, plus some image processing.
In theory I agree. The thing is that mirrors have to move multiple times to create a wide range of colors scale, in addition to the shifting itself.
Yes, I’d really like to know what they’re doing in that beefy FPGA. 
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Ahh, so the whole DMD is rotated in some fashion (or pivoted). Yes, I know this TI technology
Maybe because of pixel shifting to get 1080p and moves to merge RGB colors we have a shatter effect that written about in Image quality subjective review.
Where the pixel shift might be objectionable is very very fast action, such as sword play scenes or when punches are being thrown very near to the camera. In this case it appears the PPM GPU can’t keep up and drops the highly changing frames, and the pixel shift drawing style exacerbates the issue.
For me it is all somewhere between truths. Because I’ll have 1080p on a wall, but with some kind of shortcomings or crutches which I can’t see in first use (or in a store for preview when it will available), but I’ll recognize during usage of PPM.
I’ve read that, but I’d like to know the conditions of that test. For instance I’d be trying to playback the scene with an external HDMI device so we can rule out the PPM GPU.
Good question. I’ll try to do a 4 way test between raspberry pi 4 to PPM over HDMI, Android to PPM over USB C, playing locally on a microsd stick in the PPM, DLNA streaming, all using the same time and see if I can see any difference.
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Hi guys, it’s a very relevant topic and worthy of clearer explanation.
1080p via pixel shifting is every bit as native as almost all consumer 4K projectors. You get a 60hz refresh rate and 1920x1080 pixels on the wall.
If you don’t interpret it as 1080p, remember that other display technologies like wheel-based projectors (lamp light instead of led light) also use similar tricks: a lamp based projector has a rotating wheel which alternately shows red green and blue channels of the image. Some also have yellow or white. So you never really see the entire rgb pixel at once. In fact even on non-pixel shifting dlp the same principle applies, the mirrors alternately show each separate colour channel one after the other.
The speed of this switching is fast enough that you typically won’t notice a different even at 60hz and surely not at 24hz. But this is a bit subjective, some people are more sensitive to this, just like the “rainbow effect” on wheel based projectors.
We don’t believe that this qualifies as false marketing. On the other hand, there are many advantages to using this newer DMD than the bigger 1080p option without pixel shifting. It uses substantially less power which makes it possible to make the PicoPix Max so portable, and for the battery to last up to 3 hours long. Where it makes sense to use the larger 1080p DMDs, we’ve done so, for example on the Screeneo S and U series projectors.
Hope this helps!
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Regarding all the questions/remarks regarding to the DLP + Actuator/pixel shifting polemic… Does anyone know if the 30 000hours lifetime advertised is for the LED+actuator (so the mechanic part is included in the advertised lifetime), or if the lifetime actually is only for the LED but not for the actuator/mechanical part?
For me this is the only point which matter actually! Don’t want to be screwed with a 30 000hours LED still working but a broken actuator (and so a bricked projector!)
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4 way test observations:
Test videos: DaVinci’s Demon S02E04, night sword fight by the fire and brawl in the ship’s hold, medium quality for; Star Wars Ep IV remastered, attacking the death star scenes, very high quality file
HDMI and USB-C video input were noticably brighter but compression artifacts were also more visible vs playing locally stored and DLNA steamed versions of the same file. “Multiple sword” effect present in all versions of playback. Stuttering and dropped frames noticeable if you’re looking for it in all versions.
Then I turned auto keystone and auto focus off. Stuttering got maybe 20% better. Not perfect but a little better on scenes with huge fast motion .
My hunch is theres something that needs optimizing in the image processing stack.
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@usafballer it is native 1080p, because for each unique pixel in 1080p source you will see a unique pixel on the screen. the projector chip works on 240hz sending a different pixel every 60hz and pixel shifting to present each pixel on the right spot on the wall. so a square of 4 pixels is created using a single led pixel on the chip.
This is a pico device, that runs on batteries, and the chip inside is one intended for pico projectors. putting in a chip that would have 4 pixels for each 4 pixels shown and would need 4 times the light source, so with current light source you would get almost 4 times less light (i.e. effectively 200 lumen), instead you are getting 800 lumen as the light is concentrated on less physical pixels.
So bigger chip eats about 4 times more power, heats more, and does not go on batteries - it is no longer a pico projector.
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Interesting. Dropping frames on HDMI?
Question, are you feeding in 50/60Hz signals? If yes, what happens with 24, or vice versa?
I think that’s what I’m seeing, yes. It’s very very subtle, but does make for just a hint of jerkiness in frames with big motion. If I watch mouths of speaking actors very carefully I think I can see it there too .
I didn’t check the mode setting on the HDMI from the pi, I’ll try to remember to do that later.
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Thanks! My physics degree is rusty but I get it. Had a hard time finding the specific white paper on it though.
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I’m not sure why you are trying to compare this colourwheel projectors. The PPM is still a single chip DLP projector, the single DLP chip projectors still have to create separate Red, Green and Blue images for each frame. Yet the PPM, with the pixel shift, it has to create separate Red, Green and Blue images for each of the four pixel phases.
Yes, it has advantages in making it lower power and more compact but there are disadvantages too. which are deliberately not being talked about.
Yes, it will display 1080p60, but is it native 1080p? No. In the same way 4K pixel shift projectors will display a 4K image, the manufacturers never actually market them as being “native” 4K. The only manufacturer that I have seen use the term ‘native 4K’ is Sony, but then they really do have LCoS chips with 4096 x 2160 physical pixels. Native resolution is a specific term, and in this instance Philips is using it incorrectly.
In the same paragraph you state that it you see 1920x1080 unique pixels, but then state that a square of 4 pixels is created by a single physical pixel on the chip. Native resolution is a specific term that refers to the physical pixels ONLY. The ‘apparent resolution’, ‘perceived resolution’, or ‘displayed resolution’ is 1080p, but the native (physical pixel) resolution is most certainly not. I am not saying Philips should have advertised it as a ‘native 540p’ projector, but when they called it ‘native 1080p’ they were directly stating it was something it is not.
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There is a minor pivot of the entire DMD, and it creates 4 pixels from one mirror. It can update each pixel of that 4 pixel quad every 1/60th of a second, likely interleaved with an overall 240hz signal. I haven’t seen a good white paper on it, but this is how they can create a 1080P projected image. You keep equating each individual mirror on the DMD with “one pixel” and that’s not true since the entire DMD is in motion, as well as each mirror on the DMD being in an different state. Now, if your eye can detect in a single 1/240th second freeze frame, that only 1/4 of the pixels on the 1080P screen are being illuminated (if I’m understanding this correctly, which I leave room that I don’t), then you obviously need to look elsewhere than this PPM product, but since the entire display fully refreshes in 60hz, and the content you are displaying is going to be 60hz or lower, I’m not sure what you are complaining about here. TI advertizes it as a true 1080P, Full HD DMD, so why shouldn’t Philips get to say that as well?
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