Color Correction of Luojia3-01 Satellite Images with Partial Snow or Cloud Cover

Objectives The green channel received by Luojia3-01 satellite in Bayer imaging mode has relatively strong signals. The camera often adopts a fixed exposure and gain setting for images containing high saturation pixel values, which comprehensively leads to the color deviation of the images with partial snow or cloud cover captured by Luojia3-01 satellite.

Methods To solve the above problems, a histogram overlapping white balance method combining color compensation and cross-correlation is proposed. First, in order to further improve the details of the image, the Gamma function is constructed through the distribution proportion of the region of low gray value to enable adaptive gamma correction processing. In order to improve the similarity of the distribution of color channels, the standard deviation of the image is used to calculate the weight to compensate for the attenuation channels, and the brightness information is maintained based on YCbCr color space to avoid the background brightness change of the image. Then, in order to improve the color deviation and maintain the overlap of the color mean, the color histogram is overlapped by using the cross-correlation relationship, and the parameters are adjusted according to the features of the images with partial snow or cloud cover. Finally, subjective analysis and objective evaluation of the corrected images are carried out.

Results The proposed method has the best processing effect in retaining the information of other ground objects except snow or cloud, and the information entropy value is the largest. The calculated value of the color correlation index obtained by processing the scene images with different amounts of snow and ice or cloud coverage also reaches the optimal value, and the color correlation is the highest compared with other methods. Other color correction methods, such as gray-world algorithm and gray-edge algorithm, are not effective, and it is difficult for other methods to achieve a balance between improving the color cast and preserving image information.

Conclusions The proposed method has better color correction effect, more natural color, and can better preserve feature information.