NEW FALSE COLOR MAPPING FOR IMAGE FUSION

A pixel-based color-mapping algorithm is presented that produces a fus ed false color rendering of two gray-level images representing differe nt sensor modalities. The resulting images have a higher information c ontent than each of the original images and retain sensor-specific ima ge information. The unique component of each image modality is enhance d in the resulting fused color image representation. First, the common component of the two original input images is determined. Second, the common component is subtracted from the original images to obtain the unique component of each image. Third, the unique component of each i mage modality is subtracted from the image of the other modality. This step serves to enhance the representation of sensor-specific details in the final fused result. Finally, a fused color image is produced by displaying the images resulting from the last step through, respectiv ely, the red and green channels of a color display. The method is appl ied to fuse thermal and visual images. The results show that the color mapping enhances the visibility of certain details and preserves the specificity of the sensor information. The fused images also have a fa irly natural appearance. The fusion scheme involves only operations on corresponding pixels. The resolution of a fused image is therefore di rectly related to the resolution of the input images. Before fusing, t he contrast of the images can be enhanced and their noise can be reduc ed by standard image-processing techniques. The color mapping algorith m is computationally simple. This implies that the investigated approa ches can eventually be applied in real time and that the hardware need ed is not too complicated or too voluminous (an important consideratio n when it has to fit in an airplane, for instance). (C) 1996 Society o f Photo-Optical Instrumentation Engineers.