High embedding capacity text steganography using optimal color combinations from 24-bit space

The texts "only boats catch connotes ..." and "in the research area of text steganography ...." were not coloured in section 6 (Experimental Evaluation) as in the original manuscript.This article introduces a paradigm-shifting approach to text steganography that fundamentally redefines the capacity limits of covert communication through the synergistic integration of combinatorial color optimization and Huffman compression. By exploiting the combinatorial richness of the 24-bit RGB color space enhanced with lossless compression, we present a framework that achieves unprecedented embedding capabilities—reaching up to 400% effective capacity, representing a 17.9 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo>×</mml:mo> </mml:math> improvement over state-of-the-art permutation-based method (Sadie et al., 2023) for n <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo>=</mml:mo> </mml:math> 10 colors. Our methodology combines optimal color subset selection from 16.7 million possibilities with hybrid combinatorial–permutational encoding and Huffman compression, creating exponential growth in steganographic potential while maintaining format compatibility with standard communication channels. Theoretical analysis confirms <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="script">O</mml:mi> </mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:msup> <mml:mn>2</mml:mn> <mml:mn>24</mml:mn> </mml:msup> <mml:msup> <mml:mo stretchy="false">)</mml:mo> <mml:mrow> <mml:mi>k</mml:mi> <mml:mi>n</mml:mi> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> </mml:math> complexity scaling with only 12% compression overhead, while experimental validation demonstrates practical implementation achieving 350 to 400% capacity with only 5 to 8% cover text modification. The compression-enhanced scheme establishes new benchmarks for high-capacity steganography, offering robust security against statistical detection through dynamic palette selection, adaptive encoding strategies, and compression-induced entropy redistribution. This work represents a significant advancement in digital covert communication, providing a scalable, efficient solution for modern security requirements while enhancing both capacity and undetectability beyond existing text-based steganographic systems.