數位影像感測器之適應性色彩內插

本論文提出一種去馬賽克方法，將數位相機拍攝進來於電荷耦合元件影像感測器上以貝爾圖案排列的馬賽克影像，能經由此方法還原成接近原始色彩的全彩影像。作法上是從綠色像素上做色彩內插的計算開始，首先經由像素與鄰近區域的像素間的梯度大小區分出平滑及複雜的區域，在平滑區域的內插計算部分藉由水平及垂直的梯度當作加權來做平均。而在較複雜的區域則使用像素色差的變異數來決定缺少綠色樣本插值的插值方向來決定插值。接著用前面求出的綠色內插值來使用顏色的相關性來對藍色及紅色做內插計算，在計算完之後再利用像素與周圍像素的色差權重值來針對像素缺少藍色或紅色的色值做優化的內插計算，用來取得在各個像素中較為接近原始色彩的內插值，以完成最終的顏色重建。最後，本論文以峰值訊噪比值及CIELAB數值作為客觀上評量本論文之去馬賽克方法的效能，以及圖片的比較來當作人眼所見的主觀感受。

關鍵字

去馬賽克；電荷耦合元件影像感測器；數位相機；貝爾圖案；色彩內插；峰值信噪比； CIELAB

並列摘要

This thesis presents a demosaicing method to restore the full color image close to the original color image based on the mosaic image arranged in the Bayer pattern on the CCD image sensor. The method begins with the interpolation for the missing green pixels. By calculating the horizontal and vertical gradients in a local region with the missing green pixel as its center, we classify the color texture of the local region to be smooth or complicated. If the color texture of the local region is smooth, the missing green pixel can be computed by the weighted sum of the bilinear interpolation with Laplacian second-order correction. If the color texture of the local region is complicated, the interpolation direction of the missing green pixel is determined by the variances of color differences. After interpolating all missing green pixels, the missing red and blue pixels are estimated by taking consideration of the interpolated green pixels and the color correlation between different channels. The interpolated red and blue pixels are further refined by taking the weighted sum of the four adjacent color difference values. Finally, the PSNR value and the CIELAB value are used as objective measures to quantify the performance of the proposed demosaicing method. We also show the reconstructed images to assess the subjectively visual quality of our method.

並列關鍵字

Demosaicing ； CCD image sensor ； Digital Camera ； Bayer pattern ； color interpolation ； PSNR ； CIELAB

參考文獻

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國際替代計量

數位影像感測器之適應性色彩內插

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