AWhat changed
Ahmed, Natarajan and Rao introduce a discrete cosine transform with an FFT-based computation and report close performance to the Karhunen-Loeve transform for specified correlated-signal models and filtering/rate-distortion comparisons.
Scientific scope
Ahmed, Natarajan and Rao introduce a discrete cosine transform with an FFT-based computation and report close performance to the Karhunen-Loeve transform for specified correlated-signal models and filtering/rate-distortion comparisons. Exact 1974 IEEE Transactions on Computers C-23(1),90-93; the assessed article is on pages 90–93. Adjacent correlation/sequential-machine letters excluded. Finite cosine/Chebyshev basis and inverse, with a 2 M-point FFT computation; Comparisons use Toeplitz covariance rho^abs(i-j),0<rho<1: variance example M 16/rho 0.95; scalar diagonal Wiener filtering with white zero-mean uncorrelated noise, Table I rho 0.9/SNR 1/M 2-64; Gaussian-source rate-distortion example M 16/rho 0.9. Close-to-KLT reported within these settings, not exact eigenvectors/optimal compression for arbitrary covariances or all data. No general vector-filter/JPEG/video-codec validation. Full transform is reversible; loss requires subsequent selection/quantization. Standard tiny DCT-II matrix checks use own normalization, not certified reconstruction of original glyphs. No independent scientific/calibration certification.
Evidence
Source-linked, scoped account of the original work. The published scope states the scientific assumptions and remaining verification limits. WRS has not independently certified the full proof, experimental result or system benchmark.
Contributors
- Nasir Ahmed · SCIENCE: Original source-listed scientific author of this scoped work; byline does not determine effort fractions.
- T. Raj Natarajan · SCIENCE: Original source-listed scientific author of this scoped work; byline does not determine effort fractions.
- K. R. Rao · SCIENCE: Original source-listed scientific author of this scoped work; byline does not determine effort fractions.
- Ahmed, Natarajan and Rao, Discrete Cosine Transform, IEEE Trans. Computers C-23(1),90-93(1974), original correspondence
- IEEE-deposited Crossref identity for 1974 DCT correspondence
- DBLP exact DCT paper byline and publication identity
Provisional WRS assessment, edition 2026-10-16.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
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