Disclosed is a method for forming an image of a target from echo return data in an ultrasound system. The method is performed by first moving a probe unit containing an ultrasound transducer over a body to be imaged and receiving echo return data from the ultrasound transducer. This data is combined with output data from a sensor adapted to provide information about the position and/or orientation of the probe unit to produce a series of scanlines (81). These scanlines (81) each include echo intensity data and information defining the position and/or orientation of the scanline (81). A transform is then calculated and applied to the scanlines (81) to map the scanlines (81) to a plane of best fit. This transformed data is then mapped to a raster image formed by displaying an array of pixel (84) buffer brightness values. These values are produced by determining a first set of intersection points (83) between a centreline (82) of a first pixel row and each scanline (81) and determining a second set of intersection points for a second pixel row adjacent to the first pixel row from the first set of intersection points. Subsequently, the value of the data point on each scanline (81) which is nearest to each intersection (83) is assigned to be the pixel (84) buffer brightness value. Where such assignment would result in more than one brightness value for a particular pixel (84), the average of these values is assigned as the pixel (84) buffer brightness value.
