![]() ![]() Similar to the white point remapping, we can approximate a gamma tone curve by using a Curves adjustment: This is because the RAW sensor data is encoded as linear we perceive light in a non-linear fashion, however, where the shadow range is expanded and the highlight range is compressed, so we’ll want to account for this. ![]() We’ll also want to do some gamma conversion. Whilst rudimentary, for the purposes of demonstration we can achieve this by using a simple Levels adjustment, bringing the white point right down to remap it. This is because we count 0 as a value too (absolute black) within the range of bits. Notice the maximum values are 655, rather than 655. The RAW file I’ve chosen is 12-bit, so we need to remap its brightest pixel value-4095-to the equivalent in 16-bit, which would be 65535. For our purposes, the unprocessed image data is represented in 16-bit, which contains 65,536 levels. 12-bit contains 4,096 levels, for example, whilst 14-bit contains 16,384 levels. Most RAW data is captured at 14-bit or 12-bit precision, which determines the levels of brightness the image can contain. Without wanting to get too complicated, this is due to the captured sensor information’s bit depth. at first glance, it’s a little underwhelming. Let’s strip all that away and look at an unprocessed image. Certain RAW tools allow us to extract this data before any significant processing is applied to it. ![]() Now we know what’s in a RAW file, let’s take a closer look at the sensor image data. It’s often used to preview the image on the camera’s LCD screen, and can be used for initial previewing in RAW processing software whilst the actual RAW file is being processed and thumbnailed in the background. Embedded JPEG: a JPEG is often embedded into the RAW file, and may be full or partial resolution.Sensor image data: this is the scene information captured by the sensor, and is used to produce the final image we see on screen.camera settings like ISO, shutter speed, aperture, and sensor metadata, which is used to aid the software RAW processing. Metadata: this includes both camera metadata, e.g.Although interesting, it’s not our main concern for now. Contains information such as identifiers, byte-ordering etc. A header: common in most file formats.Despite this variance, these RAW files all follow a typical structure: RW2 (Panasonic) just to name a few examples. Most camera manufacturers use their own proprietary RAW format, and they can have various filename extensions such as. Let’s start with what’s in a typical RAW file. But why does it offer us these benefits? What is actual RAW data? And why can you dramatically alter the white balance so easily, pull highlights and push shadows, and perform other numerous tweaks that are more successful with RAW compared to JPEG? Let’s have a look. Our general understanding is that it behaves a bit like a ‘digital negative’, rewarding us with more image ‘information’ and more flexibility during editing. If you’re a photographer, you’ve no doubt come across RAW. What’s actually in a RAW file, and how does software convert it to something tangible that we can view and edit? Let’s find out. ![]()
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