A Primer on iPhone 12 HDR Video

Apple introduced many new features to its iPhone 12 lineup. Many people know about its 5G cellular capabilities, better camera (improved sensor and new ProRAW format), and faster processor (A14 Bionic chip with better performance and power efficiency). However, fewer people are aware that it also introduced a Dolby Vision HDR video recording option. This is kind of a big deal if you are a serious videographer, and it may also be a very useful feature for casual videographers like me. The purpose of this primer is to help you understand what high dynamic range (HDR) video is and why you might or might not want to enable it on your video recordings.

Let’s start by discussing what HDR video is. In short, there are limitations to the colors that computer screens can display as compared to what colors the human eye can actually perceive. Standard dynamic range (SDR) video is captured with 8-bit recordings which capture a very good representative sample of all the colors that human eyes can see. HDR video ups the game to 10-bit recordings which capture an even better representative sample of what humans can see (but still falls short of capturing everything humans can see). The result is truer pure red, pure green, and pure blue colors, as well as all color combinations of reds, greens, and blues.

Taking this a step farther, techies refer to these representative samples of colors as a “color gamut” or “color space” which you can liken to an artist’s palette.  The more colors you can mix on a palette, the better you can paint the true colors of a scene. Color spaces are represented by CIE chromaticity diagrams. CIE is French for Commission internationale de l'éclairage which was established in 1913 and is also known as the International Commission on Illumination. In a CIE chromaticity diagram, the full range of colors is represented by a horseshoe-like shape, and triangular shapes represent color spaces of a variety of different SDR and HDR video formats as depicted here:

A given display can only reproduce the color combinations that reside inside the triangle that is formed by its primary (red, green, and blue) colors. As you can see, HDR video (e.g., Rec. 2020 color space) can reproduce a larger subset of colors than SDR video (e.g., Rec. 709 color space). The end result is higher luminance (brightness intensity) and more detail in both shadows and highlights.

From what I can tell, there are similarities and differences in HDR videography and HDR photography. From a technical perspective, HDR video boils down to a wider color space. HDR photos, on the other hand, are images that are the result of the blending of multiple different exposures of the same scene, all within a single color space. Also, HDR photos can be viewed on any display, while special HDR displays are needed to fully leverage the wider color space of HDR video. So the HDR look is achieved in very different ways between HDR photos and HDR videos. However, what HDR photos and videos share in common is that you can get better representation of tonal range. Note that one can go overboard with HDR photography, and that might be the topic of another blog.

Although HDR video is “better” than SDR video, there are potential tradeoffs. First, HDR video requires more storage space than SDR video, so this may impact how much video you can save on your iPhone as well as iCloud (if you use that service). Second, because there are lots more computations involved, recording HDR video requires more energy and can drain your battery more quickly. Finally, if you share and/or edit your HDR videos, you may need to be mindful of the color spaces you want to support. Most of the common sharing options automatically adjust for differences in color space and ensure compatibility. For example, when editing and sharing HDR videos in Photos, Clips, iMovie, and other applications, you will be prompted to specify the color space. Things are currently a little more complex for Final Cut Pro where you need to create a new Final Cut Pro library and set the color processing for the library to Wide Gamut HDR and then tweak some other settings. Color space conversions and tone mapping might be the topic of another blog post, but for now check out this Apple support page and this Apple white paper for more information.

All of this leads us to a single question: Should you enable HDR video recordings on your iPhone 12? I’d say yes if all of the following are true:

• You care about getting better color quality (it might not be noticeable to casual observers but might make a difference to those who have an eye for color “trueness”)
• The differences in storage space and battery life are not a concern (probably not a significant deterrent for most people)
• You are sharing videos by “conventional” means (i.e., via Apple software applications) which automatically make adjustments or prompt you to ensure color space compatibility
• If you edit videos for the purpose of publishing them to other platforms (e.g., YouTube), then you are willing to learn about supported color spaces and the conversions between them, in case issues arise

To enable or disable HDR video on your iPhone 12, go to Settings > Camera > Record Video and toggle the “HDR Video” option. If you’re interested in learning more about color spaces, a good starting point might be this series of lessons in Khan Academy.

Photos from Mars 2020 Perseverance Rover

I previously wrote about NASA’s launch of its Mars Perseverance Rover. Yesterday it successfully landed on the surface of Mars, and you can watch recorded coverage of the landing here:

Did you know that NASA will be posting raw images that are taken from the Perseverance Rover? You can find them here.

 

I was disappointed to find only 3 low-resolution (2 of the 3 images are 320x240 pixels, and the other is 1280x960 pixels) .png files at the moment. Perhaps they will post high-resolution raw files (i.e., straight out of the camera and unprocessed) at a later time. Maybe Perseverance only had the bandwidth to send thumbnails and the original raw files will take more time to be transmitted back to earth. Nevertheless, how cool is that?

Also notice that on the Raw Images website, each photo is accompanied by an acquisition date along with its corresponding day on Mars which is referred to as a sol or a Martian day. A sol is 24 hours, 39 minutes, and 35.244 seconds long which is only slightly longer than an earth day. However, a Martian year is approximately 668 sols, equivalent to approximately 687 Earth days. All 3 of the currant images were taken on February 18, 2021 which is designated as sol 0.

I plan to check back occasionally to see if more interesting images from Perseverance are posted to the Raw Images site. While looking for photos, I also happened to find the archives of raw images from the Mars Curiosity Rover (launched in 2011) which you can view here. Happy exploring, earthlings!

COVID-19 Vaccination: How is California Doing?

It is well-known that there are numerous logistical issues related to the manufacturing and equitable distribution of COVID-19 vaccines. That being said, the vaccines are slowly but surely making their way into all 58 counties in California. The official website for California Coronavirus Response provides many resources, including a COVID-19 state dashboard where cases, deaths, tests, and vaccine administration are shown in dashboard views. While many of us are quite familiar with dashboards for the daily and total cases, deaths, and tests, the  California COVID-19 Vaccine Dashboard is a relatively new addition to these data visualizations.

The vaccine administration dashboard is simple in nature. It displays the quantity of vaccine that has been shipped, delivered, and administered throughout all 58 counties in California. As depicted above, the CDC Pharmacy Partnership for Long-Term Care Program and CDC Federal Retail Pharmacy Program doses are a subset of the total. A live and interactive view of the dashboard is available here:

COVID-19 Vaccination: Is It My Turn?

As soon as the first COVID-19 vaccine was approved in December 2020, the state of California launched its “Vaccinate All 58” campaign with the aim of providing vaccinations for residents of all 58 California counties in a safe and equitable manner.

According to the campaign, “vaccines will be administered in phases by prioritizing groups according to risk and level of exposure. Initial doses will go to California’s essential health care workers and those among our most vulnerable in long-term care settings.” For more details, see the vaccine distribution plan and the Phase 1A vaccine distribution recommendations at the California Department of Public Health website.

While this background information may be interesting and useful to some, if you’re one of millions of Californians who are wondering when it will be your turn to get vaccinated, check out My Turn. According to the site, “Find out if it’s your turn by answering a few questions. It only takes a few minutes. If you’re eligible and vaccine appointments are available through My Turn, you can schedule one. If it’s not your turn yet or appointments are not available, you can register to be notified when you’re eligible or when appointments open up.”

I am not yet eligible for a COVID-19 vaccine, but I registered to be notified and will gladly schedule an appointment for the COVID-19 vaccine as soon as supplies become available for my demographic.