{"id":6151,"date":"2020-08-30T15:21:47","date_gmt":"2020-08-30T13:21:47","guid":{"rendered":"http:\/\/www.arnaudom.fr\/wordpress\/?page_id=6151"},"modified":"2020-08-30T15:31:07","modified_gmt":"2020-08-30T13:31:07","slug":"reduction","status":"publish","type":"page","link":"https:\/\/www.arnaudom.fr\/wordpress\/reduction\/","title":{"rendered":"reduction"},"content":{"rendered":"\t\t
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Traitement des images non lin\u00e9aires avec PixInsight (2\/6)<\/h1>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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On commence tout d’abord par cr\u00e9er un clone de l’image en d\u00e9pla\u00e7ant son onglet sur l’espace de travail. On obtient l’image nomm\u00e9e M51nonlineaire_clone<\/span><\/strong>.<\/p>

\"Pix\"<\/div>

Sur cette image, je vais appliquer le process HDRMultiscaleTransform<\/span><\/strong> ou, si vous utilisez mes process icons, allez sur l’ic\u00f4ne Accentuer_les_d\u00e9tails_du_clone<\/span><\/strong>.<\/p>

On r\u00e8gle le param\u00e8tre Number of layers<\/span><\/strong> \u00e0 4<\/span><\/strong>, Number of iterations<\/span><\/strong> \u00e0 3<\/span><\/strong> et on laisse les autres param\u00e8tres par d\u00e9faut.<\/p>

\"Pix\"<\/div>

On applique le process en le d\u00e9posant sur l’image.<\/p>

\"Pix\"<\/div>

Le process a ainsi fortement accentu\u00e9 les d\u00e9tails de l’image (nous reviendrons plus loin dans le traitement sur l’utilisation et l’utilit\u00e9 de ce process).<\/p>

On utilise maintenant le process MorphologicalTransformation<\/span><\/strong> ou, si vous utilisez mes process icons, on va sur l’ic\u00f4ne Reduction_du_bruit_sur_le_clone<\/span><\/strong>.<\/p>

\"Pix\"<\/div>

Dans le menu d\u00e9roulant Operator :<\/span><\/strong> on a s\u00e9lectionn\u00e9 l’option Morphological Median<\/span><\/strong>. On l’applique sur notre clone afin d’en supprimer le bruit.<\/p>

Maintenant on reprend le process StarMask<\/span><\/strong> ou, si vous utilisez mes process icons, on va sur Masque_d_etoiles_a_appliquer_sur_le_clone<\/span><\/strong>. On r\u00e8gle comme tout \u00e0 l’heure le Noise treshhold<\/span><\/strong> \u00e0 0.40000<\/span><\/strong> et on l’applique cette fois sur le clone.<\/p>

\"Pix\"<\/div>

Le r\u00e9sultat obtenu me para\u00eet cette fois tout \u00e0 fait bien, les petites \u00ab pseudo-\u00e9toiles \u00bb qui se trouvaient en bas \u00e0 droite de mon masque pr\u00e9c\u00e9dent ont disparu.<\/p>

\"Pix\"<\/div>

J’applique mon masque \u00e0 l’image et je l’inverse (Mask\/Invert Mask<\/span><\/strong>) pour le v\u00e9rifier.<\/p>

\"Pix\"<\/div>

Si on observe le coin inf\u00e9rieur droit de l’image, seules les \u00e9toiles sont maintenant recouvertes par le masque.<\/p>

\"Pix\"<\/div>

Voil\u00e0, maintenant que je suis content de mon masque, le plus dur est fait, je vais pouvoir r\u00e9duire facilement mes \u00e9toiles.<\/p>

On n’oublie pas d’inverser<\/span><\/strong> \u00e0 nouveau le masque avant de passer \u00e0 la suite.<\/p>

\"Pix\"<\/div>

Pour r\u00e9duire nos \u00e9toiles on va utiliser \u00e0 nouveau le process MorphologicalTransformation<\/span><\/strong> ou, si vous utilisez mes process icons, aller sur l’ic\u00f4ne R\u00e9duction_des_\u00e9toiles<\/span><\/strong>.<\/p>

\"Pix\"<\/div>

Cette fois on a s\u00e9lectionn\u00e9 l’option Erosion (minimum)<\/span><\/strong> dans le menu Operator :<\/span><\/strong> afin de r\u00e9duire les \u00e9toiles. On cache le masque (mais il reste toujours actif) en faisant un clic droit et allant sur Mask\/Show Mask<\/span><\/strong>.<\/p>

On fait ensuite un preview<\/span> <\/strong>sur l’image, en choisissant bien entendu une zone de l’image contenant plusieurs \u00e9toiles relativement brillantes.<\/p>

On n’a plus qu’\u00e0 d\u00e9poser le process sur le preview<\/span> pour voir l’effet obtenu.<\/p>

Preview avant<\/span><\/strong>
\"Pix\"<\/div>
Preview apr\u00e8s<\/span><\/strong>
\"Pix\"<\/div>

Si le r\u00e9sultat est convenable, on peut supprimer le preview<\/span> puis appliquer maintenant le process directement sur l’ensemble de l’image.<\/p>

\"Pix\"<\/div>

L’utilisation des fl\u00e8ches Undo\/Redo<\/span><\/strong> permettent une nouvelle fois de v\u00e9rifier l’aspect de l’image avant et apr\u00e8s la r\u00e9duction.<\/p>

On peut refaire une seconde r\u00e9duction si on le souhaite, l\u00e0 aussi c’est ensuite au go\u00fbt de chacun de voir si l’on pr\u00e9f\u00e8re voir plus ou moins d’\u00e9toiles sur l’ensemble de l’image.<\/p>

Voici l’image centr\u00e9e sur M51 avant la r\u00e9duction d’\u00e9toiles :<\/span><\/strong>
\"Pix\"<\/div>
Et la m\u00eame apr\u00e8s la r\u00e9duction :<\/span><\/strong>
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\n\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\n\t\t\t\t<\/i>\t\t\t<\/span>\n\t\t\t\t\t\tPage 3<\/span>\n\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

Traitement des images non lin\u00e9aires avec PixInsight (2\/6) On commence tout d’abord par cr\u00e9er un clone de l’image en d\u00e9pla\u00e7ant son onglet sur l’espace de travail. On obtient l’image nomm\u00e9e M51nonlineaire_clone. Sur cette image, je vais appliquer le process HDRMultiscaleTransform ou, si vous utilisez mes process icons, allez sur l’ic\u00f4ne Accentuer_les_d\u00e9tails_du_clone. On r\u00e8gle le param\u00e8tre …<\/p>\n

reduction<\/span> Lire la suite\u00a0\u00bb<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-6151","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/pages\/6151","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/comments?post=6151"}],"version-history":[{"count":5,"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/pages\/6151\/revisions"}],"predecessor-version":[{"id":6157,"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/pages\/6151\/revisions\/6157"}],"wp:attachment":[{"href":"https:\/\/www.arnaudom.fr\/wordpress\/wp-json\/wp\/v2\/media?parent=6151"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}