---
title: "Image Processing & Stretching"
canonical: https://stackingstarlight.com/processing
description: "Processing and stretching: histogram stretching turns faint linear data into a visible image while preserving stars and controlling background."
---

# Image Processing & Stretching

> Processing and stretching: histogram stretching turns faint linear data into a visible image while preserving stars and controlling background.

Stacked data is **linear** — faint nebulosity sits just above the background and is invisible until stretched. **Histogram stretching** applies a non-linear curve that lifts the dim midtones (revealing faint detail) while holding the black point near the sky background and keeping bright stars from saturating. Done well, stretching unveils structure that was always in the data; done poorly, it crushes blacks or bloats stars. Further processing (color calibration, noise reduction, sharpening, star reduction) refines the stretched image, but stretching is the pivotal step from data to picture.

---

Source: [https://stackingstarlight.com/processing](https://stackingstarlight.com/processing) · Part of [Stacking Starlight](https://stackingstarlight.com) by Michael Kalika.

LLM resources: [LLM index (llms.txt)](https://stackingstarlight.com/llms.txt) · [Complete LLM text (llms-full.txt)](https://stackingstarlight.com/llms-full.txt) · [Markdown homepage (index.md)](https://stackingstarlight.com/index.md)