Shoulder
In the context of cinematography and imaging, the ‘shoulder’ refers to the upper portion of a film or digital camera's characteristic curve in Standard Dynamic Range (SDR) formats. It represents the transition from the brighter midtones into the highlights, where the response to light begins to plateau or level off. This describes how a camera captures and reproduces details in the highlights when working within SDR constraints.
Key aspects of the 'shoulder' in SDR include:
Compression: Within SDR, as the curve approaches the shoulder, it starts to flatten. This means the highlights in SDR are compressed, preventing them from becoming overly bright and washed out but can lead to a reduction in highlight detail if not managed correctly.
Highlight Roll-off: A smooth shoulder in SDR results in a gentle roll-off into the highlights, giving a more natural look to the brightest areas of an image. This soft transition is often sought after to avoid harsh clipping in the highlights.
Avoiding Overexposure: It's crucial not to overly rely on the shoulder even in SDR. Excessively bright highlights can lose detail, even if they don't appear blatantly overexposed.
However, with the advent of High Dynamic Range (HDR) imaging, there's more latitude and room for highlight detail. HDR can capture a broader range of luminance values, allowing for more detail in both shadows and highlights compared to SDR. This means that while the concept of the 'shoulder' still exists in HDR, it is extended, offering more flexibility in post-production and reducing the risk of highlight clipping, thereby retaining more details in brighter areas.