An infrared detector system is described in which a despeckle filter is applied to image data generated by a High Operating Temperature (HOT) detector array. The filter reads the data associated with each pixel of the image generated and compares it with selected neighboring pixels. The comparison yields a series of values that are compared to predetermined thresholds and the pixel is scored according to the number of values that exceed the threshold set. The score assigned to the pixel then determines the treatment of the pixel in the image to be generated. The data value of the pixel may be ignored, included or substituted with an alternative calculated value.