Methods for preprocessing pixel data using a Direct Memory Access (DMA) engine during a data transfer of the pixel data from a first memory (e.g., a DRAM) to a second memory (e.g., an SRAM) are described. The pixel data may derive from a color camera or a depth camera in which individual pixel values are not a multiple of eight bits. In some cases, the DMA engine may perform a variety of image processing operations on the pixel data prior to the pixel data being written into the second memory. In one embodiment, the DMA engine may be configured to determine whether one or more pixels corresponding with the pixel data may be invalidated or skipped based on a minimum pixel value threshold and a maximum pixel value threshold and to embed pixel skipping information within unused bits of the pixel data.