A 640x480 pixel image sensor has been developed for low light imaging with a practical resolution. This image sensor combined an active-matrix high-efficiency electron emission device (HEED) with a high-gain avalanche rushing amorphous photoconductor (HARP) target. To meet the requirement for a scaling of the imaging size, we developed a 2/3 in. image sensor based on an active-matrix HEED with 13.75x13.75 mu m(2) pixels. The highly emissive property of 3.8 mu A/pixel was comparable to that obtained previously from a 1 in. device. The possible effect of the pixel size scaling on the image-pickup sensitivity was compensated by a significant increase in the emission current density. The technological potential of the HEED-HARP image sensing has been further enhanced toward practical use.