roxics
Veteran
An interesting bit of news about the Amira and its new UHD ProRes option.
I'm curious how this would look.
I'm curious how this would look.
Arri Amira goes 4K?
- Thread starter roxics
- Start date
Since it uses the camera's Open Gate Mode to leverage the all of the sensor's 3414 x 2198 photosites I would hope it would be much better than attempting to up-res from a 1080P ProRes file. Of course if you have Alexa XT you could do this from the RAW files, but the Amira doesn't currently do raw recording. Even the original Alexa can't do Open Gate recording so this could be a big deal.
Time will tell but this could be beautiful footage. UHD ProRes 4444 from the 3414 x 2198 Alexa Sensor sounds pretty good to me! Might be worth a rental to check it out for sure.
starcentral
Veteran
Coming from a company who was so adversely against 4K - this is quite an interesting development.
Arri is simply providing the option for Amira owners who must deal with the hoards of ignorant producers and directors out there who demand UHD for every little production. Amira owners can now provide this without having to rent another, lesser camera system. I would think this will injure Red and Sony quite a bit because who isn't going to want an Arri UHD file instead of all the others? Amazing company and too bad Red didn't go more in this direction as I'd rather buy US made anyway. Oh well.
abel_claire
DVXuser Sponsor
Andy actually just posted a blog about this: http://blog.abelcine.com/2014/08/26/arri-adds-prores-ultra-hd-recording-to-the-amira/#more-35705
Surf it Mike
Well-known member
We are talking up-rezing from HD to UHD .....right?
starcentral
Veteran
Yes.
But its not actually HD to begin with, the Amira sensor is already around 3200x1800...
Still coming from a company with so much anti-4K marketing behind it, its a joke they resort to uprezzing as their 4K solution.
I'm absolutely baffled by their move. Good thing they have a name behind themselves to be able to pull such a stunt.
But its not actually HD to begin with, the Amira sensor is already around 3200x1800...
Still coming from a company with so much anti-4K marketing behind it, its a joke they resort to uprezzing as their 4K solution.
I'm absolutely baffled by their move. Good thing they have a name behind themselves to be able to pull such a stunt.
Surf it Mike
Well-known member
Can't help but think this is a holding move until they wheel out a true 4K (or beyond) sensor/camera.
EndCredits
Well-known member
Skyfall was uprezed from the Alexa raw files and apparently looked amazing. It was delivered in 2k. So I'd imagine the Amira uhd would look better than some native 4k cameras.
Ebrahim Saadawi
Carbonite Member
The alexa/Amira sensor is 3.4K. They're taking that resolution and doing a 1.2x upscale to 3.8K, or UHD. But since the 3.4K is not 16:9, it's probably upscaling from about 3.2K to 3.8K.
3.2K is fine by me!
3.2K is fine by me!
starcentral
Veteran
My F55 uprezzed by 1.2207032 in post now makes it a 5K camera, so I am absolutely delighted over this latest breakthrough and finally I can compete somewhat with the RED cameras on a much more even level.
Can't wait to tell my clients.
:beer:
Can't wait to tell my clients.
:beer:
Not really - it's maybe worth a bit of theory about Bayer filter sensors.
Basic principle is that for a single sensor with Bayer filtration, the luminance resolution can't be as great as the sensor resolution (as if it was used in a monochrome mode). This is because the whole deBayering process inevitably involves interpolation of values due to each photosite only being able to be red green or blue. If it's (say) a red site, values for green, blue must be interpolated (ie guessed!
) from surrounding sites.It's difficult to give an exact figure as to "how much" the effect will be, not least because it tends to be a roll off of resolution, but the generally accepted figure is something like max luminance resolution being about 75% - maybe 80% - of sensor resolution. And chrominance resolution will be less still.
That means that most "4k" cameras don't actually give full 4k resolution. Expect something more like 3840x0.8, or about 3000-3100.
And it's why decent pro large sensor cameras designed for 1080 HD will have a sensor with substantially more photosites than 1920x1080. Do the maths in reverse and you'd expect something like 33% more on each axis to end up with "true" 1080 HD - so expect at least something like 2560x1440.
More than that is better in terms of pushing aliasing out of band, so presumably why Arri have gone for what they have. It's not as much as some on here have claimed - not the effective count anyway. From the Arri website - http://www.arri.com/camera/amira/camera_details/amira/subsection/technical_data/ :
So for normal HD (1080) use it's only using 2880x1620 out of the total.
Maybe they could use more in UHD mode, but I'd be surprised if it could be as many as 3.4k - wouldn't that be running into lens coverage problems from lenses designed to properly cover the 2880x1620 area? The reason behind having such a higher total than effective count would seem to be to give an area outside of the recorded frame in the viewfinder - to see unwanted items BEFORE they come into shot?
If it's still using 2880x1620 in UHD mode, then using the 80% "rule", this still predicts horizontal res up to (2880x0.8) about 2300 lines.
So higher than 1080 HD (which is why it's wrong to just consider it "up-rezzed HD") - but nowhere near true 4k, or even what an F5/55 will give, at least as far as resolution goes.
Personally, I think it's an indication of Arri realising they've underestimated the market for 4k, period, and this is a stop gap until they can bring out their own true 4k camera. It may take a very long time for 4k to catch on for general broadcast use (if ever), but it's strongly the way the top of the market is going, such as high end drama etc. And for very good reason that's tended to be where you've been most likely to see Arri cameras recently. I wouldn't be surprised to see them worried.
But (using the link above) the actual USED area in 16:9 mode is only 2880 horizontally - not 3.4k, not even 3.2k.
The rest seems to be used for giving out of frame viewfinding. (And unlikely to be usable for actual imaging due to lens coverage issues.
I'm not doubting the images will look good - but calling the output of about 2.9k Bayer UHD seems a bit of a stretch to me.......
starcentral
Veteran
If ARRI is using "open gate" (expanded use of pixel area on the sensor to achieve 3440 x 2200) then as harddrive points out you end up affecting your FOV and DOF, and certain lenses may not cover the entire sensor area anymore.
So if I got this right, ARRI's 4K may actually appear as a combination of uprezzing as well as using a larger area on the sensor.
http://www.arrimedia.com/news/view/48/alexa-xt-open-gate
So if I got this right, ARRI's 4K may actually appear as a combination of uprezzing as well as using a larger area on the sensor.
http://www.arrimedia.com/news/view/48/alexa-xt-open-gate
Ebrahim Saadawi
Carbonite Member
Yes we don't know how much of the 3.4k sensor they're using. They might be using the 2.8K 16:9 gate and downscaling this to 2K for 2K output and upscaling it to 3.8k for UHD output. Or they might be using the entire 3.4k sensor and upscaling to UHD, which I hope they are. If it's the former, they simply should've called it a 2.8k upgrade for the Amira.
They do say a "1.2x upscale", how much resolution would that equal?
It is using more of the sensor it does in HD mode and while there appear to be some lens coverage issues they are well documented on the page linked below. Arri's done their homework and it appears that there are a bunch of lenses that will work. Apparently the Amira upgrade doesn't use as much of the sensor as the Alexa XT so it might fare even better with lens compatibility.
Smart move on Arri's part. I wouldn't have rented an Amira before when an Alexa Classic was available but now this could be the camera to beat. I have friend who has owned an Alexa for more than 2 years and no one has ever shot raw with it. Everyone loves the ProRes 4444 off the cards. Do you guys think this put pressure on Sony to deliver 4K prores with the F5 and F55 or at least 2K 4444?
http://www.arrimedia.com/news/view/48/alexa-xt-open-gate
Smart move on Arri's part. I wouldn't have rented an Amira before when an Alexa Classic was available but now this could be the camera to beat. I have friend who has owned an Alexa for more than 2 years and no one has ever shot raw with it. Everyone loves the ProRes 4444 off the cards. Do you guys think this put pressure on Sony to deliver 4K prores with the F5 and F55 or at least 2K 4444?
http://www.arrimedia.com/news/view/48/alexa-xt-open-gate
Ebrahim Saadawi
Carbonite Member
Are you certain? Haven't seen anything in their press release that indicates using a larger sensor area.
The best way: the sensor has 3414x2198 pixel native. A native 16:9 crop from that sensor is 3414x1920 pixels, then you can upscale that to 3840x2160 quite easily. In simple words if this is the case, this is a 3.4K upgrade. If they're using the same 2800x1620 area, then it's a 2.8K upgrade.