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I frequently need to deal with the contrast and brightness of raster layers in QGIS and I miss the tools in ArcGIS for this task. Should there be a plugin already developed for QGIS? If there is, where can one find it? Regards.

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If the plugin/core tool is not available (and I don't remember such tool among the plugins in the standard repositories) then please evaluate the possibility of supporting its development. –  Giovanni Manghi Dec 13 '11 at 20:15

1 Answer 1

To my knowledge, there's no plugin as such (although one would be useful). But you can achieve the same effects albeit with a bit more effort, by changing the range of RGB values for that raster layer.

On the Style tab of the Layer Properties dialog, you'll see a radio button marked Custom min / max values select it, then play around with the numbers. With a normal colour raster, the range of each channel is (0, 255), but there's nothing stopping you actually setting values outside that range to get a certain effect. There is also a Contrast enhancement option that tells QGIS what to do when it encounters an out-of-range value; you may want Clip to MinMax but play around with it to see what effect it has. Pressing Apply updates the image reasonably quickly, so while not truly interactive, its certainly usable.

As Giovanni says, QGIS is rapidly becoming a mature and popular project, and your support is always welcome. Funding a feature-request is the best way of getting a plug-in to do what you want.

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