1. A method of arranging and storing imagery data and filter coefficients in a Cellular Neural Networks (CNN) based digital integrated circuit (IC) for extracting features out of an input image, the CNN based digital IC containing NE CNN processing engines connected in a loop via a clock-skew circuit, NE is a positive integer, the method comprising: (a) determining how many imagery data groups are required for storing NIM sets of imagery data in the NE CNN processing engines, each imagery data group containing NE sets of the NIM sets of imagery data, where NIM is a positive integer; (b) circularly storing the NE sets of the imagery data of said each imagery data group in the respective NE CNN processing engines; (c) repeating (b) for the remaining imagery data groups; (d) determining how many filter groups are required for storing all filter coefficients for NF filters in the NE CNN processing engines, each filter group containing NE sets of filter coefficients and said each filter group being further divided into one or more subgroups with each subgroup containing a portion of the NE sets of filter coefficients that correlates to a corresponding group of the imagery data groups, where NF is a positive integer; (e) storing the portion of the NE sets of filter coefficients in a corresponding one of the NE CNN processing engines, the portion of filter coefficients being arranged in a cyclic order for accommodating convolution operations with imagery data received from an upstream neighbor CNN processing engine; and (f) repeating (e) for the remaining subgroups; and (g) repeating (e) and (f) for the remaining filter groups, wherein each of the NE CNN processing engines comprises: a CNN processing block configured for simultaneously obtaining M×M convolution operations results by performing 3×3 convolutions at M×M pixel locations using the stored imagery data and the stored filter coefficients, the stored imagery data representing a (M+2)-pixel by (M+2)-pixel region with the M×M pixel locations being a M×M central portion of the (M+2)-pixel by (M+2)-pixel region, where M is a positive integer; a first set of memory buffers operatively coupled to the CNN processing block for storing one of the NE sets of imagery data; and a second set of memory buffers operatively coupled to the CNN processing block for storing the portion of the NE sets of filter coefficients corresponding to said one of the NE sets of imagery data.