Ghost artifact detection and removal in HDR image processing using multi-level median threshold bitmaps

摘要

A ghost detection method for high-dynamic range (HDR) image creation using multi-level median threshold bitmapping. At each of multiple levels, median threshold bitmaps (MTBs) are generated for each original low-dynamic range image. At each level, the MTBs of the multiple original images are compared to generate a ghost map for each original image which indicates the locations of ghost pixels in the original image. For each original image, the ghost maps generated at the multiple levels are combined to generate a combined ghost map. The multiple combined ghost maps can then be used in creating the HDR image, for example, by discarding pixels in an original image that are indicated by the corresponding combined ghost map as being a ghost pixel.

主权项

1. A method for generating a high dynamic range (HDR) image from a set of M images at different exposure levels, implemented in one or more processors, comprising:
(a) for each image m of the set of M images, where m=1, 2, . . . M, the one or more processors generating N level-n median threshold bitmap (MTB) for n=1, 2, . . . N, where N denotes a highest level, each level-n MTB being a gray-scale image having the same size as the image m and 2n gray levels, generated from the image m by mapping the pixel value of each image pixel of the image m to one of the 2n gray levels, wherein the pixel value mapping maps pixel values falling within each of 2n non-overlapping ranges to a gray level, wherein the 2n ranges collectively span a total pixel value range of the image m, and wherein an approximately equal number of pixels of the image m is mapped to each gray level; (b) for each level n, the one or more processors comparing the M level-n MTBs corresponding to the M images to generate a level-n ghost map for each image m, each level-n ghost map being a binary map having a size equal to the size of the corresponding image m and having pixel values indicating whether the corresponding pixels of the corresponding image are ghost or not; (c) for each image m, the one or more processors combining the N level-n ghost maps using pixel-wise OR to generate a combined ghost map, where the combined ghost map has pixel values indicating whether the corresponding pixels of the image m are ghost or not; and (d) the one or more processors generating the HDR image using the set of M images and the corresponding combined ghost maps.