Is there a plugin or function in QGIS that allows for RGB raster color adjustments to enhance visibility of specific features captured on a map?
Example:
I'd like to enhance contrast and saturation of high resolution orthomosaic to make drainage system (below the soil) more visible and easier to vectorize. Output raster is less saturated (but better color balanced) than original photos from which was made so it makes harder to spot all lines.
It can be obviously done in i.e. Photoshop but due to file size limitations and potential loss of georeferencing I prefer to use QGIS for that.
Best Answer
If I got it right, you don't need any plugins. Just play with the stretching of the bands. There are plenty of options. This is a screen of QGIS 2.18
You can even highlight specific features, filling the Min-Max values of each band according to their range. Of course you could create some training areas in your features and do some kind of image classification, but if you just want to enhance a bit these areas just navigate above them with the value tool and fill the Min-Max values accordingly.
Here's an example of this procedure for fast stretching of features: