PPM Color Calibration Primer

How are you measuring this, what equipment / software are you using? :nerd_face:

I’m using an i1 Display Pro colorimeter for measurements, profiled by an i1Pro 2 spectrophotometer for accuracy. The colorimeter is inexpensive, fast and consistent, but it needs a bespoke correction matrix from the absolute light measurements of a spectrophotometer to be completely accurate. You can use it without and it won’t be far off, but you’re asking and I’m a nerd.

Software you can use the supplied ones, but I never have. There’s a really good functional, if ugly, free open source project called HCFR. The commercial ones are typically geared towards calibration professionals, and the cost reflects that: ChromaPure, CalMan, ColourSpace. HCFR does the job, though.

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Hi @Liersi thanks for your feedback. Could you upload your measurement results or PM them to me?

I am concerned about the low gamma you measured. It is supposed to track BT.1886 which is approximately 2.3. But it is easy to get a too-low or incorrect measurement, sometimes because of not setting the target gamma that your measurement program is expecting, but most often because of reflection from white walls back onto the screen with projection, or some other type of external effect. You can increase the accuracy by projecting from a close distance, e.g. keep the projector at 2-3 feet and the screen size about as large as a TV or smaller.

That said, gamma/EOTF curve standards only apply to controlled dark theatre environment. It’s usually better to err on the lower side, because most people will end up using it in situations with ambient light, where a pure 2.2 or BT1886 gamma will result in loss of perceived brightness. Frequently as low as 2.0 or 1.8 or a non-power curve looks better in such conditions.

The primaries are approximately DCI-P3 but it’s very difficult to get it correctly aligned at this price and size class, you’d need to order 100k or more light engines to be able to select LEDs with the right chromaticity and tolerance. Most of the engine tuning is done after-the-fact, since you can’t always pick which light engine is used in the product due to various factors.

The sharpness control should also affect HDMI, it doesn’t for you?

PS: you’re added to beta list now.

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Sure, which measurements do you need? Grayscale, Primaries? test.PrimariesSheet.csv (585 Bytes) test.GrayScaleSheet.csv (1.3 KB)

I hope this works.

You reminded me to check the references, thank you. EOTF is using BT.1886 reference. Colour space was REC709. I switched it over to DCI-P3.

The looks are about color I understand. I ran some quick measurements on a bunch of them, and gamma/EOTF always behaved the same. Are any supposed to be different here or is that intentional?

The conditions I measure in aren’t bat cave perfect, but pretty good. All directly reflecting walls are draped in black. The screen is effectively recessed into a 2-3m black hole. Beyond that reflections can get back in, but it’s minor. I have to turn on the light to find the PPX remote if I misplace it, for instance. Little black bugger :rofl:

I’ll attach my graphs for the default look 3 (thank you for the beta access) with minor adjustments for the red weakness.

You asked about sharpness. On my PPX, this doesn’t carry over to HDMI from the look of it. But judge for yourself (beware, cellphone images):

Internal:

External:

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:rofl:

Great work, I definitely want to learn more about all of this calibration stuff!
:nerd_face:

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Hi @Liersi What’s your video chip version (Settings > About)? And are you using HDMI for your measurement pattern generator, or is Android somehow involved? What EOTF tracking do you get when you “RESET” the hidden sliders from this thread i.e. without the ‘corrections’ applied?

Also, HCFR uses single shot measurements and doesn’t wait long enough to integrate the measurement in my opinion. Are you able to try with LightSpace or CalMAN too? Or tweak HCFR to dwell longer or take multiple shots per colour?

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Thanks for the response, @Philips_Support_P. I’ll get you the info you asked for tonight, as well as do further testing per your request if time permits (before/after RESET, internal Android/external HDMI). I’ve been using both Android and HDMI sources so far, and they weren’t much different, if at all. I’m in the process of setting up an old RPi as a PGenerator, which will obviously be HDMI.

I’ll also double check what settings I’m using in HCFR for the measurement to make sure. What measurement time do you recommend to get an accurate reading? Also requested a free Lightspace download from their site, it’s about time I checked it out. CalMan is too expensive for me in its current iteration. Wish they still offered enthusiast-but-not-pro licenses.

Will get back to you asap.

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How it’s work ? Can I somewhere set the color the value for green etc ?

Preset 14
Red 780
Green 110
Blue 330

If it’s stupid question sorry…

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You can’t at the moment, unless you sign up as a beta tester. An app to adjust colour is planned to go public at some point, though.

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Any further developments on improving the picture looking flat (washed out) that Liersi mentioned?
I also have an LG PH550 that my kids use and the colors and images on the LG really pops out but the PPM does look washed out or flat in comparison.

If I didn’t have the LG to compare to start with, I probably wouldn’t be thinking about this but since I do, I can’t help thinking that the PPM picture looks flat. :frowning:

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Hey, I’m glad there’s finally someone else on this soapbox. As you can see in this thread, I’ve been saying this and asking for changes for four months. I just said to my girlfriend a minute ago that if more PPX users had another projector to compare it to, they wouldn’t accept it as it is right now. It looks that flat. This isn’t subjective, it’s measurable, the gamma is way too low.

It’s a shame everything went dead here the way it did. Nothing ever came off any of this. Patience was somewhere a few months ago, now it’s obvious no one’s working on anything related.

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This proves comparison breaks happiness :smiley:
I don’t have anything to compare to but I agree that if people sees the image quality is not good enough then something has to be done if possible.

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But let’s not get too hasty here, as marketed the PPM IS a HDR10 projector after all. All those beautiful colors and the wide dynamic range are somewhere in there! If we just close our eyes and open our minds.

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I actually didn’t need a comparison, nor was I ever happy with the way the image looked. I saw it with the naked eye, right away. The measurements just confirmed it. The PPX isn’t worse than another projector, it is measurably way off any of the reference standards for video gamma. The comparison only makes it more obvious.

I was happy to wait for this to be addressed. Now I’m worried that it won’t be, and that would be crushing. People will put this down to bad contrast, which it isn’t. This is entirely fixable, as is the unnecessary sharpening on external input.

This would be a great performer if these were fixed. You can work around a cumbersome UX, but not around flaws like this.

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So what needs to happen according to you? And I don’t mean “Philips should fix it” but where do the fixes need to be done? Is it software, settings, or hardware? Would just getting “proper” settings for the color, brightness and contrast settings be enough?

I’m not a connaisseur nor expert in this field, but if you can tell me exactly what you’d want, I’ll take it to the engineering team and campaign for these changes.

An overlay of the adjustments over what ever is displayed would be what everyone wants.and not just brightness saturation and contrast

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You mean something like this?:

:bulb: :wink:

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Kind of what I meant. But also being able to adjust the RGB value while watching a movie for example. It’s a nightmare to have to go exit a program to the home screen to adjust colour values. I watch a lot of IPTV and not every stream is perfect. So it would be good to turn down the brightness or take some reds out for example.

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Want this asap asap

Hello,
Honestly I’m quite surprised reading posts like this; from the beginning the PPM showed some problems giving good images, and we are waiting a way to adjust colors, sharpness etc as it was done to “passion home cinéma” for his blog review… months ago, maybe 8?

We really need to talk again about what should to be done? After all this time?

Personally i lost any trust in people like Ivo, I’m Sorry, not because Ivo isn’t a good guy but just because they feel the obligation to give answers to questions where is not competent at all.

At the beginning i was really involved on this forum tryng to give help to others and to Philips in order to ameliorate the PPM, now my suggestion is to take it easy and use the PPM as it Is without hoping a big improvement!

if the improvement will arrive i’ll take It like a lottery gift!

Anyway in one year with no more software support will be much more difficult to use all this (new) features!

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