Marcelo Andrade da Costa Vieira

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A new restoration methodology is proposed to enhance mammographic images through the improvement of contrast features and the simultaneous suppression of noise. Denoising is performed in the first step using the Anscombe transformation to convert the signal-dependent quantum noise into an approximately signal-independent Gaussian additive noise. In the(More)
This work proposes a new restoration method to improve mammographic images by using Anscombe Transform and Wiener Filter to quantum noise reduction. Besides, it is performed an image enhancement by using a restoration inverse filter, calculated based on the image system modulation transfer function (MTF). This pre-processing technique were used for a set of(More)
PURPOSE This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. METHODS The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues(More)
This work proposes a preprocessing technique to enhance microcalcifications on digitized mammographic images based on a frequency domain band pass Butterworth filter. The parameters for the filter are obtained from specifications of cutoff frequency and band width that define the dimension of the structures that should be enhanced by the filter. In this(More)
The objective of the present study was to determine the reproducibility of the pixel values obtained with the Digora system (Soredex, Finland). Exposures were standardized, with variation in exposure and scanning time of two photostimulable phosphor plates containing a stepwedge image. The smallest variation in pixel values ranged from 50 to 75%, with the(More)
OBJECTIVES This study applied a simple method to evaluate the performance of three digital devices (two scanners and one digital camera) using the reproducibility of pixel values attributed to the same radiographic image. METHODS Using the same capture parameters, a radiographic image was repeatedly digitized in order to determine the variability of pixel(More)
The design, optimization, and validation of many image-processing or image-based analysis systems often require testing of the system performance over a dataset of images corrupted by noise at different signal-to-noise ratio (SNR) regimes. A noise-free ground-truth image may not be available, and different SNRs are simulated by injecting extra noise into an(More)