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GAMMA FILTER [5 records]

Filter results by subject field Alphabetical list of terms

Filter results by subject field

Alphabetical list of terms

Record 1 2007-01-31

English

Subject field(s)
  • Remote Sensing
DEF

A digital filter that performs digital signal processing, and is able to adapt its performance to optimally suit the input signal.

CONT

An adaptive filter uses a filtering window that runs over the entire image pixel-by-pixel, generating new (filtered) values of the pixels. As the name suggests, an adaptive filter can adapt to the varying nature of an image by adjusting the coefficients of the filtering window depending upon the local variance in the intensity values of pixels.

OBS

Adaptive filters mainly include the Kuan filter, the LEE filter, the Frost filter and the Gamma MAP filter.

OBS

adaptative filter: term officially approved by the RADARSAT-2 Terminology Approval Group (RTAG).

French

Domaine(s)
  • Télédétection
DEF

Filtre numérique dont les coefficients, estimés au sens d'un critère donné, s'adaptent aux variations des signaux reçus.

CONT

Le filtre adaptatif consiste à ajuster la puissance du filtre en fonction des critères des statistiques locales de l'image. Ce filtre peut être utilisé lorsque le rapport signal sur bruit est faible. Ce type de filtre réduit le bruit en conservant le maximum de détails dans l'image.

OBS

filtre adaptatif : terme uniformisé par le Groupe de travail de la terminologie de RADARSAT-2 (GTTR).

Spanish

Campo(s) temático(s)
  • Teledetección
Save record 1

Record 2 2006-06-01

English

Subject field(s)
  • Remote Sensing
DEF

[A filter used] to remove random noise while preserving high frequency features (edges).

CONT

The Gamma filter performs gamma map filtering. Gamma filtering is primarily used on radar data to remove high frequency noise(speckle) while preserving high frequency features(edges). The Gamma Map filter was first proposed by Kuan.... Lopes modified the Kuan Map filter by assuming a gamma distributed scene and setting up two thresholds. The gamma filter size ranges from 1 to 11. Different filter sizes will greatly affect the quality of processed images. If the filter is too small, the noise filtering algorithm is not effective. If the filter is too large, subtle details of the image will be lost in the filtering process. A 7x7 filter usually gives the best results.... The GAMMA filter performs spatial filtering on each individual pixel in an image using the grey level values in a square window surrounding each pixel. The dimensions of the filter must be odd, and can be from 3x3 to 11x11 pixels.

CONT

Gamma Filter yields the best smoothing and despeckling. Moreover, it seems to keep the edges without blurring the minimum. Eight textures are applied, based on the cooccurrence matrix. These textures include mean, variance, homogeneity, contrast, dissimilarity, entropy, second moment, and correlation.

OBS

The term MAP stands for Maximum A Posteriori.

OBS

gamma filter : term officially approved by the RADARSAT-2 Terminology Approval Group(RTAG).

PHR

Gamma-gaussian, gamma-beta, gamma-gamma MAP filter.

French

Domaine(s)
  • Télédétection
DEF

Filtre utilisé pour enlever les bruits aléatoires des images, tout en préservant les caractéristiques les plus pertinentes (bordures).

OBS

Pour le lissage et le déchatoiement des images, ce filtre surclasse tous les autres filtres.

OBS

filtre gamma : terme uniformisé par le Groupe de travail de la terminologie de RADARSAT-2 (GTTR).

Spanish

Save record 2

Record 3 2006-01-17

English

Subject field(s)
  • Remote Sensing
CONT

The Kuan filter smoothes the speckle in the image data without removing [image] edges or sharp features.

CONT

The Kuan filter is similar to the LEE filtre but makes fewer simplifying assumptions in the calculations.

OBS

Adaptive filters mainly include the Kuan filter, the LEE filter, the Frost filter and the gamma MAP filter.

OBS

Kuan filter: term officially approved by the RADARSAT-2 Terminology Approval Group (RTAG).

French

Domaine(s)
  • Télédétection
CONT

Le filtre de Kuan [...] est semblable au filtre de LEE mais les estimateurs de variance locaux (weighting function) sont différents. Puisque le filtre de Kuan n'applique pas d'approximation au modèle original, il peut être considéré supérieur au filtre de LEE.

OBS

Le filtre de Kuan appartient à la famille des filtres adaptatifs.

OBS

filtre de Kuan : terme uniformisé par le Groupe de travail de la terminologie de RADARSAT-2 (GTTR).

Spanish

Save record 3

Record 4 2002-03-21

English

Subject field(s)
  • Remote Sensing
CONT

The LEE filter (Laplacian Egde Enhancement filter) is useful in detecting edge and linear features [contrasts] in imagery.

OBS

Adaptive filters mainly include the Kuan filter, the LEE filter, the Frost filter and the Gamma MAP filter.

OBS

LEE filter: term officially approved by the RADARSAT-2 Terminology Approval Group (RTAG).

French

Domaine(s)
  • Télédétection
OBS

Le filtre de LEE sert au lissage des données-images tout en préservant les contours et les contrastes d'image.

OBS

Le filtre de Kuan appartient à la famille des filtres adaptatifs.

OBS

filtre de LEE : terme uniformisé par le Groupe de travail de la terminologie de RADARSAT-2 (GTTR).

Spanish

Save record 4

Record 5 2002-03-15

English

Subject field(s)
  • Remote Sensing
CONT

[The] Frost filter allows [the reduction of] speckle while preserving edges in a radar image. This filter is intermediate between LEE filter and median filter.

CONT

The Frost filter differs from the LEE and Kuan filters [in such a manner] that the scene reflectivity is estimated by convolving the observed image with the impulse response of the SAR system.

OBS

Adaptive filters mainly include the Kuan filter, the LEE filter, the Frost filter and the Gamma MAP filter.

OBS

Frost filter: term officially approved by the RADARSAT-2 Terminology Approval Group (RTAG).

French

Domaine(s)
  • Télédétection
CONT

En imagerie radar, le filtre de Frost sert à atténuer le chatoiement de l'image tout en préservant les contours. Ce filtre [est considéré comme] un filtre intermédiaire entre le filtre de LEE et le filtre médian.

OBS

filtre de Frost : terme uniformisé par le Groupe de travail de la terminologie de RADARSAT-2 (GTTR).

Spanish

Save record 5

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