*3.4.2 ASPP module*

It applies four parallel Atrous Separable Convolutions (ASC) with different dilation rates; this allows analysing the extracted features at different scales. Whereas, The ASC is a depthwise convolution with atrous convolutions followed by a pointwise convolution. The ASPP output is 1024 channels.

#### *3.4.3 Decoder module*

The outputs of the ASPP module are concatenated and passed through a 1 1 convolution to reduce the number of channels to 256. This result is upsampled by a factor of four and concatenated with low-level features of the same dimension.

Since the input structure should be aligned with the output structure, thus it is appropriate to share the low-level information, such as edges or shapes, with the higher ones. Then, we apply two 3 3 ASCs and, finally, a 1 1 convolution with two-channel, so that a binary mask is obtained. This result is upsampled by a factor of four to recover the original size of the image.

*Deep Learning-Based Segmentation of Cellular Membranes in Colorectal Immunohistochemical… DOI: http://dx.doi.org/10.5772/intechopen.108589*
