Inverse Tone Mapping High Dynamic Range Images

HDR (High Dynamic Range) imaging is an area of increasing importance but most display devices still has LDR (Limited Dynamic Range). While retaining important visual information, various techniques have been proposed for compressing the dynamic range. When used for range compression, multi-scale image processing techniques widely used for many image processing tasks have a reputation of causing halo artifacts. However, they can work when properly implemented as demonstrated. A symmetrical analysis-synthesis filter bank is used and a local gain control is applied to the sub-bands. As also shown, the technique can be adapted for the related problem of inverse tone mapping in which a HDR image is converted to a LDR image and later expanded back to HDR image.