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I'm working with QGIS 2.18 (windows) and the useful atlas tools. My covering layer is a polygon layer (20 features). My atlas template is composed by 4 map elements representing different images raster (3 multibands) located on the same area.

I use the option proposed in the tab called "object property" to lock the layer and the style of the layer (lock layers / lock style for layers). For each raster, I want to be able to automatically apply and set the raster style and enhance the contrast "local histogram stretch".

I join a screen shot representing my atlas template.

enter image description here

Is there a way to automatically assign a contrast stretch ("local histogram stretch") for all my map elements and for each of my 20 atlas sheet?

  • seems like you could use the style manager to save a default style, this will write out a .qml file and then you can apply to others from there. View>>Panels>>Layer Styling, then go to Style Manager tab. – rickD Oct 12 '17 at 21:49
  • Hello. Thanks but according to me your proposal does not allow to assign automatically a contrast stretch to my atlas 's map elements. I would like to affect a "local histogram stretch". So this means that the stretch varies according to each map elements. In my opinion, your proposal allows you to save the style for the entire raster. But thank you for your reply. – user35117 Oct 13 '17 at 8:45
  • Usefull reply here : osgeo-org.1560.x6.nabble.com/… – user35117 Oct 16 '17 at 9:32
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According to Andreas Neumann (http://osgeo-org.1560.x6.nabble.com/qgis-atlas-set-raster-images-s-contrast-stretch-td5338133.html):

This is possible in QGIS 3, as it has the local contrast (stretch and clip at updated current extent) as a styling option of a raster layer.

I know that this may not be the answer you want, but you can already install and use QGIS 3 in parallel with 2.18 - if you just use QGIS 3 to generate the atlas.

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