One note I would add is that the 2-click option does not work with a singleband pseudocolor renderer(neither does the raster toolbar which offers a 1-click stretch). So I think updating the right-click>"Stretch using current extent" to work with singleband pseudocolor would be excellent to include. Also, I agree that min/max would be good as a default, for singleband at least. Beyond that I like the sound of solution and I would love to see this functionality in QGIS.
a On Fri, Sep 2, 2016 at 3:38 AM, Even Rouault <even.roua...@spatialys.com> wrote: > Hi, > > There has been interest expressed to improve the usability of the contrast > enhancement function. Basically there are workflows where you want the > min/max > values used by contrast enhancement to be updated each time you pan or zoom > the canvas. From what I've seen, here's what currently exists: > - a long method (6 clicks): through the Style tab of the layer properties > - a faster method (2 clicks): through the "Strech using current extent" of > the > contextual menu of the layer panel. > > When you have several rasters loaded, even the 2-click method is > inconvenient, > so there's a need for a 0-click solution (once the layers have been > configured) > > Another shortcoming in the current implementation is that the settings of > the > "Load min/max values" foldable group are not persistant, which requires re- > setting them if you're not happy with the default Cumlative count cut > method. > And if you use the "Strech using current extent" menu item, the genuine > min/max values are used (not the 2-98% cumulative count cut) > > So I was thinking to something along the following lines: > - make the min/max settings persistant > - remove the "Load" button and "Clip extent to canvas" checkbox, and > replace > them by 3 radio buttons to determine the scope of statistics : "Whole > raster", > "Current canvas" and "Updated canvas". See the attached > proposal_min_max.png. > The function of the Load button would be replaced by the general Apply / OK > buttons. > - when the user manually enters the min/max values, the 2 groups of radio > buttons (method to compute min/max and scope of statistics) would be > unchecked > so that is is clear that they don't come from computed statistics. I also > think that when you select "Current canvas", once the Apply/OK buttons have > been pushed, the checked state of Current canvas shouldn't be saved. This > way > when you display the layer properties you have a good idea of where the > current min/max values come from. > - make the "Strech using current extent" method honour the way min/max are > computed in the min/max settings instead of using systematically the > min/max. > So when "Updated canvas" would be selected, it would have no (extra) > effect as > expected. > > Any opinions ? > > Even > > -- > Spatialys - Geospatial professional services > http://www.spatialys.com > > _______________________________________________ > Qgis-developer mailing list > Qgis-developer@lists.osgeo.org > List info: http://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-developer >
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