An infrared thermal imaging system based on un-cooled infrared focal plane array technology is presented. To reduce costs

a 16 pixel × 4 pixel infrared focal plane array detector MLX90620 is used to detect the infrared intensity of radiation. An improved algorithm which combines bilinear interpolation and polynomial interpolation is used to get high quality and high resolution infrared image

and the image is interpolated by polynomial interpolation

to improve its resolution to 64 pixel × 16 pixel

then bilinear interpolation method is adopted to advance image resolution from 64 pixel × 16 pixel to 256 pixel × 64 pixel. Experiments on human body shows that the algorithm can not only improve image resolution

but also keep more details.