Method and processing unit for generating an output feature map

A method performed by a processing unit for generating an output feature map, the processing unit comprising an input feature map storage configured to store input feature map blocks 40, 41, 42, 43. The input feature map storage is read by the processing unit to generate output feature map blocks 44, 45. The method comprises sequentially loading input feature map blocks into the input feature map storage, using a first input feature map block 43 stored in the input feature map storage to generate a partial computation for a first output feature map block 44, and reusing the first input feature map block 43 stored in the input feature map storage to generate a partial computation for a second output feature map block 45 without reloading the first input feature map block 43 into the input feature map storage.