Add Raster Stretching/Enhancement based on portion of image in current window

[jgr007]

I'd like to have the option to do enhancement/stretching based on the statistics of the portion of the image displayed in the current window (vs. stats of entire image). I posted a message to the developer list and Peter Ersts suggested that this would be a good one to add to the code base and asked that I file a ticket on it. Hopefully this is the right way to do that. :)

[ersts]

It turns out this actually would have been a little easier as a plugin, but it should be core functionality. The issue at hand is that the layer itself does not know what is currently being display. draw() accepts a render context object which is used to determine what portion of the layer to display, but that object comes from the map canvas.

There is a solution in the trunk now, r 12015.

[cgsbob]

Replying to ersts:

It turns out this actually would have been a little easier as a plugin, but it should be core functionality. The issue at hand is that the layer itself does not know what is currently being display. draw() accepts a render context object which is used to determine what portion of the layer to display, but that object comes from the map canvas.

There is a solution in the trunk now, r 12015.

What a handy addition to qgis! I was thinking that it would be nice to have this functionality available using the legend right click menu.

[ersts]

The option "Stretch using current extent" was added to the right-click legend menu in r14031. This option is not available for "Palette" layers. If this menu option is selected while displaying a single band with a color map or as pseudo color, it will switch the layer back to gray scale. Additionally if, you to not have a contrast enhancement set stretch to min max will automatically be selected.