Beginning with version 2.38, Camera FV-5 can shoot 16-bit RAW photos as well as the usual JPEG on the OnePlus One, regardless whether you run the original CyanogenMod ROM shipped with your phone (based in Android 4.4 KitKat) or the newer CyanogenMod CM12 based on Android 5.0 Lollipop. RAW photos are stored in the industry-standard DNG files (Adobe Digital Negative). RAW photographs store exactly the information as it was captured by the sensor, with no processing applied. Therefore, you can extract a lot of detail from the RAW image, and also you can process it to your liking, adjusting exposure from a greater dynamic range source, adjusting white balance, and applying any kind of noise reduction algorithm, just to name a few. The DNG images include color correction instructions embedded on the DNG metadata to help the DNG converter software better develop the RAW image into a JPEG image. The image correction instructions generated by Camera FV-5 result in images with slightly different color and contrast that the one used by the stock camera RAW photos, because the internal RAW capture implementation is also different.
First, ensure that you have the latest version of Camera FV-5 from the Play Store, specifically the version that introduces the RAW capture in the OnePlus One. Then, follow these steps to enable RAW capture.
When you enable RAW capture, you will get JPEG+DNG (i.e. both developed and raw images). The RAW photos are stored as DNG files. The file names match the ones of the JPEG files that you can completely customize. Also, DNG files are stored on the same folder used to store the JPEG images, and you can choose any folder on your internal memory to store your pictures.