MATLAB Source Code for Bidirectional Conversion Between RGB and HSI Color Models

This article explores the bidirectional conversion between RGB and HSI color models with comprehensive MATLAB source code. The RGB color model represents colors through combinations of three primary channels: Red (R), Green (G), and Blue (B). In contrast, the HSI model characterizes colors using three fundamental attributes: Hue (H) defining color type, Saturation (S) indicating color purity, and Intensity (I) representing brightness level. The MATLAB implementation includes two core conversion functions: 1. RGB-to-HSI Conversion Algorithm: - Normalizes RGB values to [0,1] range - Calculates Hue using trigonometric functions based on normalized R, G, B components - Computes Saturation through minimum/maximum RGB value differences - Derives Intensity as the average of R, G, B components - Handles special cases for achromatic colors (when R=G=B) 2. HSI-to-RGB Conversion Algorithm: - Processes colors sector by sector based on Hue values (0-120°, 120-240°, 240-360°) - Applies sector-specific transformation equations to reconstruct RGB values - Ensures proper normalization and boundary checking The provided MATLAB code demonstrates practical implementation of these color space transformations, enabling better understanding and application of both color models in image processing and computer vision tasks. The conversion functions include error handling for invalid input values and maintain color consistency during bidirectional transformations.