In astrophotography, stretching is the process of adjusting the brightness and contrast of an image to reveal details that may be hidden in the original data. The goal of stretching is to bring out the faint details in the image while preserving the overall color and contrast of the object being photographed.

Stretching is typically done using specialized software, such as Adobe Photoshop or PixInsight, and involves adjusting the levels, curves, or other tone mapping tools to manipulate the brightness and contrast of the image. The process is often subjective and depends on the observer’s preferences and the nature of the object being photographed.

During stretching, astrophotographers often use a histogram to visualize the distribution of pixel values in the image. By adjusting the levels or curves, they can adjust the brightness of the image and selectively enhance certain features or areas of the object.

Stretching can be a powerful tool for revealing details in astrophotography, but it must be used carefully to avoid overstretching or exaggerating the features in the image. Overstretching can result in noise, artifacts, or other distortions that may reduce the quality of the final image.

Overall, stretching is an essential step in astrophotography that allows astrophotographers to bring out the details and beauty of celestial objects that may be hidden in the raw data.