August 2015
The remote Control for Xiaomi Yi cameras app allows you to control your Xiaomi Yi camera over Wifi. The app supports live preview and media download over Wifi as well. Features: - Start/stop capturing and change the capturing mode (video, photo, time-lapse, burst, self-timer). Change settings. Yi Home 1080i Camera This could easily be a 5 start review but for a one issue which gets the yi camera experience off on the wrong foot. The Yi only works with a 2G network, that in and of itself is not reeally a big problem. The problem arises when you go through the setup process. Get full remote control of your Xiaomi Yi Action Camera. Key Features: Live preview. Change camera modes (photo. Download the latest apps to use with your YI Action Camera or your YI Smart Camera. Preview, store, and share instantly.
Introduction
The Xiaomi Yi action camerawas introduced in early 2015.It is similar in many respects to some of the popular GoPro cameras, butcosts considerably less (about $70 as of August 2015). Unlikemany of the cheap GoPro competitors, the Xioami Yi has an excellent sensor (16megapixel Sony Exmor R BSI CMOS) and processor (Ambarella A7LS),and is capable of producing excellent images and video. Unfortunately, straight out ofthe box, its performance isn't nearly as good as it could be. This page describessome tweaks and modifications that can dramatically improve this camera'simage quality.
Image Quality Weaknesses
The Xiaomi Yi has an excellent 16 megapixel sensor and a 155 degree fisheyelens that is surprisingly sharp across the most of the frame. By default, theimages it produces are pretty good, but there are a number of issues thatnegatively affect image quality:
- Poor Focus. The camera has a fixed-focus lens that has been pre-focused at thefactory. Unfortunately, it seems that the Xiaomi Yi has been focused for the'selfie enthusiast', optimally focused on subjects only a few feet from thecamera. My guess is that this was a deliberate design decision. After all,with such a wide-angle lens and small sensor, even if the camera is focusedat 6 feet, the depth of field is enormous, and subjects at much greater distancesare technically 'in focus' as well. The problem is that 'in focus' doesn't meanoptimally focused (see my depth-of-field calculator for more information).And, in the case of the Xiaomi Yi, objects at distances of more than about 20 or 30 feet appear visiblysofter than those at 6 feet, even though they are all technically 'in focus'.Interestingly, when viewing the video produced by the Xiaomi Yi it is muchharder to detect this focus problem than when looking at the still images. Thisis because the video is 1080P, so each individual video frame only contains 2 millionpixels. In contrast, the still images contain 16 million pixels, making this focusproblem much more apparent. When downsized from 16 million to 2 million pixels,the softness in distant objects is hard or impossible to detect.
- High ISO. By default the Xiaomi Yi typically chooses fast shutterspeeds. This probably makes sense for an action camera that might often be inrapid motion, and slow shutter speeds could produce blurry images.However, in order to achieve these fast shutter speeds, the Xiaomihas to also use a high ISO setting. Higher ISO settings add noise and reduce detailin images.
- Aggressive Noise reduction. The Xiaomi Yi shoots JPEG images, and applies anaggressive amount of noise reduction to the images. As a result, the imageslook very smooth, but a lot of fine detail has been lost. Perhaps to counteractthe detail loss as a result of the noise reduction, the Xiaomi Yi applies aconsiderable amount of sharpening to the image. The result is that distant objectsoften appear plasticky and featureless.
- JPEG only. The camera only produces JPEG images. RAW files are favoredby many photographers for their ability to allow for much greater post-processinglatitude than JPEG images.
Viewed at small sizes, the images from Xiaomi Yi look good... | ...however, viewing at 100% reveals poor focus and loss of detail due to aggressive noise reduction |
Improving Image Quality
Luckily, all of these problems can be solved with some minor hacking. This is probablya good place to issue a standard disclaimer that hacking your camera will almostcertainly void the warranty, and could damage or break the camera. That said,I haven't experienced any problems doing anything described here.
- Focus adjustment. As mentioned above, the camera's focus was fixed at thefactory and was not designed to be adjusted by owners. However, it isn'timpossible. The lens' focus can be adjusted simply by rotating it. Rotatingclockwise makes it focus at longer distances; counter-clockwise rotation causesit to focus at shorter distances. In order to rotate the lens, the camera'scase must be opened and some glue that normally prevents the lens fromrotating must be removed. Youtube has many videos that illustrate how to dothis. Most users find that a small clockwise rotation of about 15-20 degreescauses the camera to be optimally focused at longer distances.
- Manual selection of ISO, exposure, whitebalance, noise reduction (and more). The Xiaomidoesn't offer the user any ability to change many important photographic optionssuch as ISO, shutter speed, white-balance, etc. However, it turns out thatthe Xiaomi has an undocumented 'back door' that allows for adjustment of theseparameters as well as many others: When the camera starts up it checks to seeif there is a file on the SD card with a name of 'autoexec.ash'. If so, itwill read that file and execute any commands contained in that file. Thecommands are undocumented, but intrepid hackers have already worked out whatcommands can be used to adjust exposure length (shutter speeds of up to 8 seconds),ISO (100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600) and to disableauto-whitebalance (which sets the white-balance at a daylight preset).The Xiaomi Yi's noise reduction can be turned down somewhat, but not completelydisabled (not yet, at least). There are many resources on the web with information about theautoexec.ash file and the commands that can be used to adjust the Xiaomi Yi's settings. Hereare a couple of good places to start reading: one,two.
- RAW format. The autoexec.ash file can also be used to force the camerato produce raw files (in addition to the JPEG images that the camera produces).Raw files contain the raw sensor data prior to any sharpening, noise reduction,contrast adjustment, white balancing and compression. All these adjustments can be made later when processingthe images. When raw capture is enabled on the Xiaomi Yi, it will createtwo files for each shutter press: one with a 'jpg' file extension and the other with a 'RAW' extension(e.g. YDXJ0298.jpg and YDXJ0298.RAW). The raw files aren't in a format thatis readily readable by most software, but can be easily converted (details below) to a standardDNG file which canbe opened by Photoshop and other image editing software.
Rotating the lens clockwise by about 10-15 degrees
produces much better focus on distant objects
Even afer focus adjustment, setting ISO 100 and turning down noise reduction as much as possible, JPEG images still exhibit loss of fine detail... | RAW file allows for exposure and white-balance adjustment (shown here) as well as retention of much more fine detail |
Xiaomi Yi Configurator (XYC)
Although the autoexec.ash file allows the user to adjust the settings on thecamera, it isn't always convenient or easy to adjust the contents of the file,particularly when out 'in the field' photographing. My solution was to createa small program called 'Xiaomi Yi Configurator' (XYC) that runs inside the cameraand allows the user to configure exposure, ISO and other settings via aninteractive menu. Once the user has changed the settings, XYC creates a new autoexec.ashfile and the settings are applied next time the camera starts.
XYC takes advantage of the fact that the camera runs a small version of theLinux operating system, and can run a telnet server. This means that anytelnet client can connect to the camera and run the XYC program on the Xiaomi Yi camera.Telnet clients are freely available for all operating systems (e.g. Windows,iOS, Android, iPhone, Unix, etc.) This makes XYC a truly cross-platform approachfor changing settings on the Xiaomi Yi camera. This thread has moredetails on accessing the Xiaomi Yi using telnet.
The steps for running XYC vary a little depending on what type of computeror phone you are using and the specifics of your telnet client software, butthe general procedure is as follows:
- First time only: Copy the xyc.sh file to the top level of the camera's micro SD card.
- First time only: Create an empty file (no contents) named 'enable_info_display.script', and placethis at the top level of the camera's micro SD card. This file instructsthe camera to start the telnet server when the camera turns on.
- Turn on the Xiaomi Yi's wifi, and connect your computer/phone to the xiaomi Yi'swifi network. (Using the official Xiaomi Yi app to connect to the Xiaomi Yi'swifi network may be helpful in this step).
- Use your telnet client to establish a telnet connection to the Xiaomi Yi.the IP address for the camera is 192.168.42.1. The user ID is 'root', andthere is no password.
- First time only: If this is the first time you are running XYC, you willneed to change the file permissions for xyc.sh so that it can be executed. Inorder to do this, type the following command at the telnet console:
chmod 755 /tmp/fuse_d/xyc.sh - Run XYC with the following command:
/tmp/fuse_d/xyc.sh - XYC will present a menu of choices that allow you to view/adjustcamera settings (exposure, ISO, auto-whitebalance, noise reduction and RAW format).Type a number to select a menu choice. Settingscan be changed by entering numeric values or 'y' or 'n' responses. In mostcases hitting 'enter' will retain the default/current value for a setting.XYC also allows you to create a time-lapse script that will execute the nexttime the camera starts. The camera's built-in time-lapse feature does notappear to work correctly with RAW files, so XYC's time-lapse feature maybe useful instead if shooting RAW files.
- After making any desired configuration changes, restart the camera in orderfor them to take effect.
XYC main menu on an Android phone | XYC settings adjustment using an Android phone |
Creating a time lapse script | Showing SD card information |
Creating DNG Raw Files
The raw files produced by the Xiaomi Yi need to be converted to a DNG formatso that they can be read by standard raw processing software. I use a modifiedversion of the procedure outlined in this thread.In order to create DNG files from the Xiaomi Yi's raw files, two steps are necessary:
- Run raw2dng, a program originally created for Nikon Coolpix cameras butalso works well with the Xiaomi Yi files, to convert the raw data into a DNG file.I use the command-line version of this program (available here) rather thanthe graphical version because it allows for the automation of DNG creation (see below)
- Run exiftool (available here)to modify the 'whitelevel' and 'blacklevel' points in the DNG file, and embedXMP metadata sothat the DNG files open in Adobe Camera Raw with defaults that approximate theappearance of the Xiaomi Yi's JPEG images.
Converting RAW files to DNG format
Final Thoughts
The Xiaomi Yi is a great little camera, but it is a pity that it comes fromthe factory with a lens focused for the selfie-enthusiast and image settingsthat destroy a lot of the detail that the camera is capable ofcapturing. I hope that a future version of the Xiaomi Yi (a Xiaomi Yi Pro, perhaps?)might be targeted towards photographers who want more manual control over the cameraand the ability to capture detailed landscapes where distant subjects are well focused.The current Xiaomi Yi can be hacked to do this, but most people won't bother,and if they look too closely at the images may end up concluding thatthe camera just isn't very good.
Downloads
- Xiaomi Yi Configurator (XYC) program and raw conversion batch file (Version 0.2.0. Updated Dec 5 2015)
Xiaomi Yi Software For Mac Windows 10
Links and More Reading
- Max Lyons Software: http://www.tawbaware.com/
- Max Lyons Image Gallery: http://www.tawbaware.com/maxlyons
- Contact: maxlyons@tawbaware.com