compression d'images appliquee aux angiographies cardiaques

2.6.2. Descriptif résumé de l'algorithme MPEG ....................................... 51
2.6.3. Principaux artéfacts ....................................................................... 52
2.7. Méthode développée par Philips : MLOT ...................................................... 53
CHAPITRE I-2 GENERALITES SUR LES IMAGES MEDICALES ET ANGIOGRAPHIQUES :
ACQUISITION, COMPRESSION ET STANDARDISATION..................... 56
1. Compression des images médicales ........................................................................ 57
1.1. Tendance en radiologie................................................................................. 57
1.2. Tendance en cardiologie ............................................................................... 58
2. Standards d'images médicales ................................................................................. 59
2.1. Pourquoi un standard .................................................................................... 59
2.2. Historique des standards ACR-NEMA et DICOM.......................................... 59
2.3. DICOM et la compression ............................................................................. 59
3. Standards médicaux et standards industriels ........................................................... 60
4. Principe et particularité de l'angiographie cardiaque................................................. 61
5. Quelques propriétés des images d'angiographies cardiaques.................................. 63
CHAPITRE I-3 ALLOCATION DES BITS DANS LA TECHNIQUE FULL FRAME DCT .. 67
1. Introduction ............................................................................................................... 68
2. Coding of the DCT Coefficients ................................................................................ 69
2.1. Full Frame DCT coding scheme.................................................................... 69
2.2. Normalized DCT coefficents.......................................................................... 70
2.3. Zonal splitting of the DCT plane .................................................................... 70
2.4. Uniform optimal quantizer.............................................................................. 72
2.5. Integer bit allocation ...................................................................................... 74
2.6. Coding of the quantized DCT coefficients ..................................................... 75
3. Experimental results and discussion......................................................................... 75
3.1. Experiments................................................................................................... 75
3.2. Discussion ..................................................................................................... 76
3.3. Perspectives .................................................................................................. 78
4. Conclusion ................................................................................................................ 78
CHAPITRE I-4 COMPRESSION FULL FRAME DCT ET RENFORCEMENT DE CONTOUR
80
1. Introduction ............................................................................................................... 82
2. Should the raw image or the processed image be compressed? ............................. 82
2.1. Edge enhancement filtering of digital cardiac angiograms ............................ 82
2.2. Edge enhancement after data compression.................................................. 84
2.3. Edge enhancement before data compression............................................... 84
2.4. integration of the edge enhancement in the compression /
decompression process................................................................................. 85
2.5. Integration of de-enhancement in the decompression scheme ..................
by inverse filtering.......................................................................................... 86
2.6. Improvement of the de-enhancement of compressed images ....................
by regularization ............................................................................................ 86
3. Full Frame DCT coding and directional quantization ................................................ 88
3.1. Block Diagram ............................................................................................... 88
3.2. Full Frame DCT and zonal splitting ............................................................... 88
3.3. Bit allocation, quantization and coding .......................................................... 89
4. Experimental results and discussion......................................................................... 90
4.1. Results from simulations of the compression ................................................ 90
4.2. Results on coded images .............................................................................. 91
5. Conclusion ................................................................................................................ 93