FiLMiC LogV2 increases the dynamic range of the iPhone XS, iPhone XS Max and iPhone XR up to 12 stops in ideal conditions. Here’s how it works.

The engineers at FiLMiC Pro have combined Apple’s new imaging dynamics with their own computational imaging module called “Cubiform”. The result is improved dynamic range and optimized color encoding when using the new FiLMiC LogV2 profile in the FiLMiC Pro app. FiLMiC LogV2 works on all iOS devices and most Android camera 2.0 API capable devices.

Early iPhone XS Max Tests

In September 2018 I had the opportunity to test the iPhone XS Max with the FiLMiC Pro team in Barcelona. We used the latest build of FiLMiC Pro at the time, which wasn’t optimized for Apple’s new hardware. It was an interesting experience to say the least. A lot has changed in the new devices. It was clear then, that the FiLMiC team had a lot of work ahead of them.

I shot an impromptu and unplanned video a day or two after the iPhone XS Max dropped into Apple stores. While it showed a hint of the potential in Apple’s new hardware and image processing, the grade was a disaster. Apple’s new dynamic tone mapping was constantly fighting with the app’s own image processing. This resulted in very inconsistent shots.

I was subsequently roasted in the video comments for the grade… thanks everyone, you guys are ruthless. The internet has no mercy.

Apple’s new image processing seemed like Voodoo at the time, but things have become much clearer in the months since.

Fast forward to November 2018. I started testing a secretive build of FiLMiC Pro incorporating a brand new custom computational imaging module. This module, called “Cubiform” had been in development for quite some time.

Now this is known as FiLMiC LogV2.

FiLMiC Pro LogV2 X-Rite ColorChecker Test | iPhone XS Max

One thing has become very clear in my months of testing FiLMiC LogV2 on the latest Apple devices. Using a reference chart, such as the X-Rite ColorChecker Passport Video is the best way to ensure consistency in color correction. FiLMiC Pro is now optimized for Apple’s new image processing, but there are still inconsistencies and shifts that are tough to correct without a fixed reference.

What is FiLMiC LogV2?

The performance of the Apple A12 chip allows the FiLMiC Pro engineers to perform more complex math in real-time. The new algorithms in FiLMiC Pro work to complement Apple’s new dynamics and smartHDR, not fight against it.

This results in up to 12 stops of dynamic range from the iPhone XS, iPhone XS Max and iPhone XR under ideal conditions. Even the iPhone SE and iPhone 6S Plus get a 1 to 1.5 stop boost when using the FiLMiC LogV2 profile, approaching 10 stops of dynamic range.

I don’t have first hand experience of how FiLMiC LogV2 is performing on Android devices but the results seem to be similar.

FiLMiC LogV2 Dynamic Range Test Charts

First let’s look at the charts, then I’ll explain a bit about how this is achieved.

As you can see, the latest generation iPhones show a notable increase in dynamic range. Even the iPhone SE without a neural engine manages an extra stop of dynamic range when shooting with FiLMiC LogV2.

Dynamic Range Test Methodology

The tests were performed with a Xyla 21 stop dynamic range testing chart in a light sealed room. All test footage was captured at 4K extreme (H.264) with a framerate of 24fps and a manual white balance of 3800K. Electronic stabilization was disabled.

Below is FiLMiC Pro’s testing methodology as officially documented.

Optimized 8-bit Color Encoding

FiLMiC LogV2 is silky smooth to color grade. It resists the banding and other artefacts of a conventional 8-bit log gamma encoding. Also, FiLMiC LogV2 is not as desaturated as you’d expect. This is because luminance and chrominance are processed separately.

Only when grading some extreme styles did I need to employ some debanding on skies. With a lot of normal looks, this would not be necessary.

FiLMiC LogV2 is close to the limit of what can be done with 8-bit 4:2:0 video from a smartphone.

Beyond this Apple would have to allow or enable encoding to higher video color bit depths. LG and Sony are both making moves in this direction. It seems inevitable that Apple will follow.

How FiLMiC LogV2 Works

FiLMiC Pro doesn’t simply reduce global contrast on an already baked in video stream. If this was the case, the result would be a huge compromise in recorded image information and quality. Furthermore, the problems associated with manipulating 8-bit encoded video in post would be made even worse.

Instead, FiLMiC Pro translates the source 8-bit luminance and chrominance information into a 64-bit space. This information is used to model an expanded luma and chroma map in a mathematical process called gamma vectorization. The result, is a computed fidelity greater than the 8-bit precision of the individual source RGB elements.

Finally, this 64-bit scalar representation of the image is mapped into an 8-bit container for encoding. The output bits are in fact brand new, sampled from the model rather than directly from the source input stream. The resulting image is made up of brand new optimized pixel values, preserving more overall dynamic range and better tonal coherence.

How does FiLMiC LogV2 hold up in post?

Over the past months I’ve shot many tests, mostly with an X-Rite Video ColorChecker Passport under a variety of conditions. I’ve over-exposed, under-exposed, shot with and without ND filters. As long as white balance and exposure are correct, FiLMiC LogV2 is capable of producing truly excellent images.

FiLMiC Pro LogV2 holds up to under exposure quite well, within reason. However, there is no possible recovery of clipped highlights. For the best results in post, carefully watch any highlights that you want to protect. There is little room for error, and limited room for correction, but there is enough room, as long as you take the time to white balance and expose correctly.

I’ve created two video tutorials and written up an article to teach you exactly how shoot with FiLMiC LogV2 and color correct easily by using the X-Rite ColorChecker Passport Video: Shoot and Color Grade FiLMiC LogV2 with the X-Rite Colorchecker Video

FiLMiC have a deLog lut and deFlat lut available for download that help give you a good starting point to getting your video close to Rec.709. You will still need to tweak things after applying the lut in order to line everything up on the scopes. The lut is useful if you don’t use a reference chart, but not necessary if you do.

FiLMiC LogV2 Tips

Use the ColorChecker grey card reference to set and lock white balance often. The light can change quickly outside and throw off your color. Always position the grey card reference so it is evenly illuminated by your key light source or full ambient light. Use the zoom function to fill the frame with the grey card.
Shoot your ColorChecker color chart at the beginning of each camera setup or position. Ensure the chart is illuminated evenly by your key light source or full ambient light and is clearly visible in the frame. Lastly, avoid reflections in the black reference chip to ensure you get a clear black point reference.
FiLMiC Pro’s exposure reticle works very well, you can place it over the brightest area of the image, and lock it once set. For example, this is often the brightest part of the sky or a white object. Set and lock your exposure after locking white balance.
Record the highest possible bit-rate “FiLMiC Extreme”.
Avoid high frame rates for maximum image quality.
Download your FiLMiC Pro video files using iTunes, don’t ever save or export to the iOS camera roll.
You can use the FiLMiC Pro deLog or deFlat lut as a starting point for color correction in post if you find it easier.
Use your recorded XRite Video ColorChecker Passport chart as a reference to make corrections to levels, hue and saturation for each shot that you have recorded a chart. This will guarantee a technically correct Rec.709 image.

Disclaimers

FiLMiC LogV2 and FiLMiC Flat do not correct identically.

It’s best not to mix FiLMiC Flat and FiLMiC LogV2 video as there are differences in tone even after manual correction using the chart. It is possible to match them with more adjustments. However, this can be time consuming and tricky.

Extreme high contrast and backlit scenes.

Very high contrast backlit scenes can cause severe problems. This is because Apple’s dynamic tone mapping and smartHDR attempts to reduce extremes of contrast. In some cases, it will raise shadow and midtone levels too close to highlight levels. The result is an unusable image that cannot be corrected.

Conclusions

FiLMiC Pro’s “Cubiform” image processing combined with Apple’s smartHDR and dynamic tone mapping result in a very usable high dynamic range image when using FiLMiC LogV2. However, shifts in exposure and levels still result in inconsistencies.

These inconsistencies can be corrected easily by shooting and color correcting using a reference chart. FiLMiC LogV2 video also responds well to creative color grading. In conclusion, excellent results can be achieved when these methods are followed.


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