title: Multiscale contrast enhancement for radiographies: Laplacian Pyramid versus fast wavelet transform.
abstract: Contrast enhancement of radiographies based on a multiscale decomposition of the images recently has proven to be a far more versatile and efficient method than regular unsharp-masking techniques, while containing these as a subset. In this paper, we compare the performance of two multiscale-methods, namely the Laplacian Pyramid and the fast wavelet transform (FWT). We find that enhancement based on the FWT suffers from one serious drawback-the introduction of visible artifacts when large structures are enhanced strongly. By contrast, the Laplacian Pyramid allows a smooth enhancement of large structures, such that visible artifacts can be avoided. Only for the enhancement of very small details, for denoising applications or compression of images, the FWT may have some advantages over the Laplacian Pyramid.
authors.affiliation: Philips Research Laboratories, Division Technical Systems, Hamburg, Germany. dippel@etech.fh-hannover.de
authors.forename: Sabine
authors.initials: S
authors.lastname: Dippel
authors.forename: Martin
authors.initials: M
authors.lastname: Stahl
authors.forename: Rafael
authors.initials: R
authors.lastname: Wiemker
authors.forename: Thomas
authors.initials: T
authors.lastname: Blaffert
mesh_terms: D000465:Algorithms; D016477:Artifacts; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008327:Mammography / Q000379:methods; D010363:Pattern Recognition, Automated; D011856:Radiographic Image Enhancement / Q000379:methods*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012886:Skull / Q000000981:diagnostic imaging