Before we can understand Apple ProRAW, we need to know what the RAW format is – the original name is “RAW Image Format”, which means “unprocessed”. An image recorded in RAW format is the raw data that the image sensor converts from a captured light signal to a digital signal.
The biggest advantage of the RAW format is that there is a lot of room for post-production adjustments.
Although the RAW format is not uncommon anymore, iPhone has been able to capture photos in RAW format on third-party software such as RAW+ and Halide. So what’s the difference between ProRAW and RAW images recorded by third-party software?
According to Apple at the press conference, ProRAW allows photographers to take photos in RAW format as well as using Apple’s computational photography technology. It offers many of the features of multi-frame image processing and computational photography, such as Deep Fusion and Intelligent HDR, combined with the depth and latitude of the RAW format.
Apple has built a new image pipeline that combines the various data processed by the CPU, GPU, ISP and NPU into a new deep image file. And things like sharpening, white balance, and tone mapping become photo parameters instead of being composited directly into the photo. This gives users full creative power over color, detail, and dynamic range.
ProRAW is supported by all four cameras in the iPhone 12 Pro series, but not when using Portrait mode. In addition, as the A-series chip performance continues to refine, there is no shutter delay when using ProRAW, and RAW files are computationally generated at the moment the photo is taken. Compared with RAW files taken by third-party software, ProRAW adds computational photography technology to it, which theoretically results in better quality negatives and leaves more room for creators to play.
Apple says it has provided an API for third-party apps to take photos in ProRAW format. But again, this should be limited to the iPhone 12 Pro series. Generally speaking, cameras take photos in RAW format at the mainstream level of 12bit and 14bit, and some high-end medium-format cameras can also reach 16bit. The larger the number, the higher the color depth and the richer the photo information. The larger the number, the higher the color depth and the richer the photo information, but the larger the size.
ProRAW can achieve 12bit color depth, which is enough for cell phones and other mobile devices, after all, the current top mobile device screen can only display 10bit color depth. In addition, considering the memory capacity of cell phones, ProRAW is about 25MB per photo, so theoretically, 14bit photos have four times the amount of data than 12bit, and the size will increase accordingly.