With their 2019 8-Series and 6-Series, TCL introduced the iPQ Calibration app. Designed to run on iOS devices and certain Android models, it is meant to help someone calibrate their TV without needing extra equipment or to hire a professional to do it for them. Now that the iOS version has been released, we decided to use it on our 2019 75” TCL 825 TV and see how it compares to doing a full calibration using CalMAN and thousands of dollars in equipment.
How TCL iPQ Calibration Works
The TCL iPQ Application doesn’t perform a complete calibration, but instead focuses on the grayscale from 50% to 100% in 10% increments. To do so, it installs an app into the Roku TV platform and when you launch the iPQ App on your phone it will detect the TV and automatically start the Roku app. The app will then load a series of videos, which are full field test grayscale test patterns with a target rectangle on them. Using your phone, you take a series of photos using the target rectangle for alignment, and that data is fed back to the TV. The TV then makes adjustments to the grayscale based on your photos, and then you do a second series of photos to measure how much the grayscale changed and if it improved or got worse. In all, the whole process takes under 10 minutes from start to finish.
When it’s done, the TCL iPQ app presents you a screen showing how much your image improved, including dE2000 error levels and xy coordinates for the grayscale targets. You can then choose to apply these settings to the grayscale or keep your existing settings. We measured the TCL 825 in Movie mode, leaving the brightness where it was already set and doing it in a standard living room where there is some ambient lighting. We considered doing it with the backlight set to 200 nits and in a completely dark room, but went with the way we thought most people are likely to use the app.
In our test, the TCL iPQ App reported that our grayscale dE2000 from 50% to 100% fell from 2.18 to 1.35, on average. In every case the adjusted image was more accurate than the starting image. But one question remained for us: Is the app accurate? To test this we measured the TCL 825 before and after the iPQ calibration using CalMAN software and a Klein K-10A meter that was profiled to the TCL screen, using the SDR Analysis workflow in CalMAN. Since this is reference grade equipment, we were certain of the results that it provides to us.
When we look at the data, we see that the grayscale on the TCL 825 actually has an increased red tint compared to before calibration with iPQ. So why is the iPQ calibrated image worse than before? There are a number of possible reasons. TCL is having to use the average of all the iPhone cameras (we used an iPhone 7+ for the test) and our specific phone could easily be different than the average. Without being able to profile the camera we don’t know how accurate it is. It’s also possible that some ambient light, or the daylight from the windows, was impacting the white balance of the camera. Unlike the Klein K-10A, light is entering the image here and can impact the results we are getting.
To see what the TCL 825 is capable of, I performed a full calibration using CalMAN software. Having done this on the TCL before, I left the colors alone and stuck to grayscale, as doing the colors before led to noticeable issues in the resulting image. I only made minor adjustments to the grayscale as well to avoid introducing artifacts or banding into the image. Even the best color management system can introduce errors if you push it too far, so knowing the limits is what a calibrator has to be aware of.
Doing this by hand I was able to greatly reduce the overall grayscale error on the TCL and move the gamma closer to the desired 2.2 target. It took me under an hour to perform the manual calibration, including the setup of equipment, but the results were much better than what the iPQ Calibration App was able to provide and made the TCL even better. It started out great, but can improve with a full calibration, though I only calibrated for SDR and not HDR in this test.
iPQ Calibration App Conclusions
The idea of the iPQ Calibration App excited me, as if someone could improve the grayscale of their TV without having to buy anything else, it would be great. Maybe it won’t provide the full performance of a professional calibration, but just improving the grayscale would be a big improvement for many TVs. Unfortunately, in our testing it looks like the iPQ Calibration App managed to make the grayscale worse, not better, and so at least in my case I wouldn’t use it. On other TVs or with other phones, maybe the results are different, but for a user there is no way to be able to be certain of that.
In the end, we think this holds promise for the future, but it’s not quite there yet. Maybe if the TV is too bright for phone cameras to work accurately, TCL can make the TV automatically reduce brightness in the future, or offer suggestions to do this in a dark room. Both of these might the app performance, but we would need to do more testing to see. Since users aren’t told this and wouldn’t know to check, we left the TV at the default settings since that was the most common scenario. So today I wouldn’t use the iPQ App, but I’m hopeful that TCL can improve this in the future.