My guess is: No. If the screen itself supported HDR, they almost surely would have touted it, even if it weren't enabled software-wise. It's always possible, of course, but my guess is that it's a hardware limitation.
EDIT: To answer the post above me... There's more to HDR than just increasing the brightness. It has to do with the level of control over the incremental brightness of the individual pixels, especially at near-minimum. If the cutoff for the OLED panel used (meaning, everything below a certain brightness = "off") is too high, then there's simply no way to display true HDR, certification or no.
There is that possibility. Maybe the LG-made P2XL supports it, but not the HTC-made P2, and Google doesn't want to draw attention to that. However, if that's the case, they may never actually enable it on the XL, so that they can keep the two phones on the same level. Remember, they've made a point to say that the two phones are equal except for screen size.Actually there's a big possibility of the phone supporting it.
Besides the fact that the first gen. Pixels support it, (it would weird to have it on those but not the Pixel 2 phones), the Pixel 2 XL most likely uses the same panel as the V30, which is Dolby vision/HDR10 compliant. So it's not a hardware limitation. I'd expect to see it supported out of the box.
There is that possibility. Maybe the LG-made P2XL supports it, but not the HTC-made P2, and Google doesn't want to draw attention to that. However, if that's the case, they may never actually enable it on the XL, so that they can keep the two phones on the same level. Remember, they've made a point to say that the two phones are equal except for screen size.
I really hope that you're right, and that the XL (at least) does support it, and does get enabled. I just have a bad feeling that if it were going to happen, Google would have already made reference to it. It IS a major selling point, after all.
Google themselves said the original Pixel twins will support HDR through software, but as of 10/25/17, YouTube wasn't showing HDR on my Pixel XL. It does show on my Pixel 2 XL, though.Agree. This phone is HDR compatible. And the videos are the best I have EVER seen on a phone! The color accuracy is tremendous and almost breath taking really. Can't believe how good this display is. Also, HDR is not just a "max brightness" or "4k only" feature. The actual [hardware] plays a role in color representation. Honestly, this is the best display on a phone I have used. Amazing.
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The hardware! That's why. The XL uses a much higher resolution/spec display. My OnePlus 3 uses a similar AMOLED display as the regular Pixel 2. And guess what...no HDR! Because the display can't render it. Also, you're saying that the original Pixel phones automatically enable HDR? Play a YouTube video and tell me if it detects HDR.