ST_PixelAsPolygon
Name
ST_PixelAsPolygon — Returns the polygon geometry that bounds the pixel for a particular row and column.
Synopsis
    
     geometry
     
      ST_PixelAsPolygon
     
     (
    
    raster
    
     rast
    
    , integer
    
     columnx
    
    , integer
    
     rowy
    
    
     )
    
    ;
   
Description
Returns the polygon geometry that bounds the pixel for a particular row and column.
Availability: 2.0.0
Examples
-- get raster pixel polygon
SELECT i,j, ST_AsText(ST_PixelAsPolygon(foo.rast, i,j)) As b1pgeom
FROM dummy_rast As foo
    CROSS JOIN generate_series(1,2) As i
    CROSS JOIN generate_series(1,1) As j
WHERE rid=2;
 i | j |                                                    b1pgeom
---+---+-----------------------------------------------------------------------------
 1 | 1 | POLYGON((3427927.75 5793244,3427927.8 5793244,3427927.8 5793243.95,...
 2 | 1 | POLYGON((3427927.8 5793244,3427927.85 5793244,3427927.85 5793243.95, ..