An image acquisition system for machine vision systems decouples image acquisition from the transmission of the image to a host processor by using a programmable imager controller to selectively disable and enable the transmission of data to the host and by using a system of buffers to temporarily store image data pending allocation of memory. This enables the image acquisition system to acquire images asynchronously and to change the exposure parameters on a frame-by-frame basis without the latency associated with the allocation of memory for storage of the acquired image. The system architecture of the invention further permits interruption and resumption of image acquisition with minimal likelihood of missing data. Data throughput is further enhanced by transmitting to the host only that data corresponding to the region of interest within the image and discarding the data from outside of the region of interest at the camera stage.