This investigation presents an embedded analog spatial filter, EASF, in a current-mode CMOS image sensor. The EASF successfully identifies the output value of the pixel in B/W so as to benefit specific real world applications. Over the last few years, image quality has been improved by better progress in CMOS process technology; however, low cost issue regarding the integration of backend circuit still is an important competition point in imager design. Embedding an analog mask filter in a CMOS image sensor not only reduces cost, but also improves speed and simplicity of design integration with the backend image processing circuit. In this paper, a 66 x 66 embedded sensor array has been implemented in TSMC 0.35 μm CMOS process. Each pixel occupies a 13.8 μm x 9.8 μm area with a fill factor of 31.2%. The power consumption is 71.14 mW when the sensor operates at 32 frames/sec.