---
title: "The Signal Journey — From Photon to Pixel"
canonical: https://stackingstarlight.com/signal-journey
description: "Follow a photon end to end: from deep space through the telescope and sensor, then calibration, stacking, and stretching to a finished image."
---

# The Signal Journey — From Photon to Pixel

> Follow a photon end to end: from deep space through the telescope and sensor, then calibration, stacking, and stretching to a finished image.

This page traces one photon's journey and, with it, the whole pipeline. **1) Capture:** photons cross light-years, enter the telescope, and are recorded as a noisy raw frame. **2) Calibration:** bias/dark/flat frames remove the camera's electronic baseline, thermal signal, and optical defects. **3) Stacking:** dozens to hundreds of calibrated frames are aligned and averaged, raising SNR by √N and rejecting outliers (satellites, cosmic rays). **4) Stretching:** the faint linear data is non-linearly stretched so dim detail becomes visible without blowing out stars. The result: a clean, detailed image from individually unusable frames.

---

Source: [https://stackingstarlight.com/signal-journey](https://stackingstarlight.com/signal-journey) · 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)