Does a procedure like Polygonize raster to vector exist in QGIS that can do the following:
I have a raster image, a shapefile (.shp) with all the regions of interest and I need a vector output with those polygons only.
As @Joseph correctly stated, the closest to my need is as he suggests:
You use the Clipper tool with the shapefile as the mask to output a raster showing your region of interest. You then use this output as the input to the Polygonize tool (no need to use a mask). This will produce a vector output of your clipped raster.