  Pixel Processor Arrays (PPA) present a new vision sensor/processor
architecture consisting of a SIMD array of processor elements, each capable of
light capture, storage, processing and local communication. Such a device
allows visual data to be efficiently stored and manipulated directly upon the
focal plane, but also demands the invention of new approaches and algorithms,
suitable for the massively-parallel fine-grain processor arrays. In this paper
we demonstrate how various image transformations, including shearing, rotation
and scaling, can be performed directly upon a PPA. The implementation details
are presented using the SCAMP-5 vision chip, that contains a 256x256
pixel-parallel array. Our approaches for performing the image transformations
efficiently exploit the parallel computation in a cellular processor array,
minimizing the number of SIMD instructions required. These fundamental image
transformations are vital building blocks for many visual tasks. This paper
aims to serve as a reference for future PPA research while demonstrating the
flexibility of PPA architectures.
