{"id":9704,"date":"2015-04-26T10:49:37","date_gmt":"2015-04-26T10:49:37","guid":{"rendered":"https:\/\/groupeastronomiespa.be\/astrogas\/gain-noise-stack-ii\/"},"modified":"2025-06-08T22:46:05","modified_gmt":"2025-06-08T20:46:05","slug":"gain-noise-stack-ii","status":"publish","type":"post","link":"https:\/\/groupeastronomiespa.be\/astrogas\/gain-noise-stack-ii\/","title":{"rendered":"Gain, Noise & Stack (II)"},"content":{"rendered":"

Pour r\u00e9duire les effets du seeing en imagerie plan\u00e9taire, les temps de pose sont souvent r\u00e9duits, quitte \u00e0 sous-exposer.
\nIn planetary imaging, the exposure time is often reduced in order to help freezing the seeing, even if it leads to underexposure.<\/em><\/p>\n

En imagerie de protub\u00e9rance solaire, r\u00e9duire le temps de pose permet de capturer la surface et les protub\u00e9rances en une fois.
\nFor solar prominence imaging, a shorter exposure time allows capturing the surface and the prominences in one shot.<\/em><\/p>\n

Pour \u00e9lever le niveau de signal, sans augmenter le temps de pose, on peut jouer sur le gain de la camera, au d\u00e9triment du niveau de bruit.
\nFor increasing the signal level without increasing the exposure time, one can increase the camera gain, at the cost of the noise.<\/em><\/p>\n

Mais l’empilage qui sera fait permettra de r\u00e9duire le bruit de toute fa\u00e7on.
\nBut the later stacking allows reducing the noise anyway.<\/em><\/p>\n

L’image de gauche est faite avec un gain de 300. Stack de 150 brutes. Milieu: l\u00e9ger ajustement par courbe de la m\u00eame image. Droite: gain pouss\u00e9 \u00e0 600 et stack de 200 brutes. Le m\u00eame renforcement a \u00e9t\u00e9 appliqu\u00e9 sur chaque image.
\nThe left pic is realized with a gain set to 300; stack of 150 raws. Middle: the same, with a slight curve adjustment. Right: the gain is pushed to 600; stack of 200 raws. The same sharpening has been applied on each pic.<\/em><\/p>\n

\"\"<\/a><\/p>\n

Une comparaison objective de l’effet final du gain est difficile, car m\u00eame si les images ont \u00e9t\u00e9 captur\u00e9es dans la foul\u00e9e, les conditions de seeing ne sont jamais exactement les m\u00eames. Mais augmenter le gain n’est pas si effroyable.
\nAn objective comparison of the final effect of the gain is difficult; even if the pics have been captured the one after the other one, the seeing conditions are never exactly the same. But increasing the gain is not that terrible.
\n<\/em>
\nCS
\nAlex<\/p>\n\n\n

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\n Veuillez voter<\/span>\n <\/div>\n <\/div>\n","protected":false},"excerpt":{"rendered":"

Pour r\u00e9duire les effets du seeing en imagerie plan\u00e9taire, les temps de pose sont souvent r\u00e9duits, quitte \u00e0 sous-exposer. In planetary imaging, the exposure time is often reduced in order to help freezing the seeing, even if it leads to underexposure. En imagerie de protub\u00e9rance solaire, r\u00e9duire le temps de pose permet de capturer la […]<\/p>\n","protected":false},"author":16,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[3],"tags":[],"class_list":["post-9704","post","type-post","status-publish","format-standard","hentry","category-astrobricolage"],"_links":{"self":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9704","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/users\/16"}],"replies":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/comments?post=9704"}],"version-history":[{"count":1,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9704\/revisions"}],"predecessor-version":[{"id":11980,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9704\/revisions\/11980"}],"wp:attachment":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/media?parent=9704"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/categories?post=9704"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/tags?post=9704"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}