融合色差梯度和颜色相关性的Bayer成像插值方法

Bayer Interpolation Method by Integrating Color-Difference Gradient and Color Correlation

  • 摘要: 为减轻卫星影像数据星地传输压力,Bayer成像模式被越来越广泛地应用于遥感卫星的成像系统,由于Bayer影像中每个像素只存储一个颜色通道的信息,存在信息缺失,因此必须经过Bayer成像插值重建为全彩色影像才能用于后续应用。现有多数Bayer成像插值方法存在地物边缘处细节缺失和色调偏移问题。针对上述问题,提出了一种融合色差梯度和颜色相关性的Bayer成像插值方法。首先提取原始Bayer影像的各通道间色差梯度信息,使用归一化的色差梯度函数赋予各方向色差估计值的相应权重,使插值沿着边缘方向进行,以保护地物边缘处细节信息,然后利用不同颜色通道间的相关性设置色比约束,调整局部滑动窗口内3个通道的相对比例,以改善插值结果中的色调偏移现象,使重建的全彩色影像色调真实、细节完整。通过在模拟影像和珞珈三号01星获取的真实Bayer影像上的实验对比,所提方法与对比方法相比,重建影像在地物边缘处的伪色问题有明显改善,具有最高的峰值信噪比、结构相似性指数和最低的均方误差、自然图像质量评价分数,且与参考影像相比没有空间分辨率损失。所提方法已成功应用于珞珈三号01星数据处理系统中,进行在轨和地面的Bayer成像插值处理,为珞珈三号01星数据的各项应用提供了有效保障。

     

    Abstract:
    Objectives In order to alleviate the pressure of satellite image data transmission between satellite and ground, the Bayer imaging mode is increasingly being used in remote sensing satellite imaging systems. The information loss occurs because each pixel in the Bayer image only stores information from one color channel. Therefore, a full-color image must be reconstructed by Bayer interpolation for subsequent applications. However, the existing interpolation methods suffer from false colors at image details and overall color tone shift issues.
    Methods In response to the above issues, this article proposes a Bayer interpolation method by integrating color-difference gradient and color correlation. First, the proposed method extracts the color difference gradient information between each channel of the original Bayer image, and uses a normalized color difference gradient function to assign corresponding weights to the estimated color difference values in each direction. The interpolation is carried out along the edge direction to protect the detail information at the edge. Then, the color ratio constraints are set according to the correlation between different color channels, and the relative proportion of the three channels in the local sliding window is adjusted to improve the color shift phenomenon in the interpolation results, which makes the reconstructed full-color image have real color tones and complete details.
    Results The experimental comparison is conducted on simulated images and real Bayer images obtained from Luojia3-01 satellite, and the proposed method has significantly improved the false color problem at the edges of ground objects. Compared the comparison methods, the proposed method has the highest peak signal-to-noise ratio and structural similarity index, and the lowest mean square error and natural image quality evaluation score.
    Conclusions The proposed method can effectively improve the problem of missing details at the edges of ground features and enhance the quality of reconstruction. It has been successfully applied to the data processing system of Luojia3-01 satellite to interpolate Bayer images in orbit and on the ground, providing effective guarantees for the various applications of Luojia3-01 satellite data.

     

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