OpenCV的 - 实现拆分和合并为DCT

问题描述

我想实现在Android上DCT code。我使用的分割和合并方法来获取图像的原始颜色。

I am trying to implement a DCT code in Android. I'm using the split and merge method to obtain the original colors of the image.

下面是code的代码片段

Here is the snippet of the code

image = Highgui.imread(imageName);

secondImage = new Mat(image.rows(), image.cols(), CvType.CV_32FC3);
image.convertTo(secondImage, CvType.CV_32FC3);

int m = Core.getOptimalDFTSize(image.rows());
int n = Core.getOptimalDFTSize(image.cols()); // on the border add zero values

Mat padded = new Mat(new Size(n, m), CvType.CV_32FC3); // expand input image to optimal size

Imgproc.copyMakeBorder(secondImage, padded, 0, m - secondImage.rows(), 0, n - secondImage.cols(), Imgproc.BORDER_CONSTANT);

List<Mat> planes = new ArrayList<Mat>();

Core.split(padded, planes);
List<Mat> outplanes = new ArrayList<Mat>(planes.size());
for (int k = 0; k < planes.size(); k++) {
    outplanes.add(new Mat(padded.size(), CvType.CV_32FC1));
}

Mat trans = new Mat(padded.size(), padded.type());

for (int k = 0; k < planes.size(); k++) {
    Core.dct(planes.get(k), outplanes.get(k));
}

List<Mat> ioutplanes = new ArrayList<Mat>(outplanes.size());
for (int k = 0; k < planes.size(); k++) {
    ioutplanes.add(new Mat(padded.size(), CvType.CV_32FC1));
}

for (int k = 0; k < planes.size(); k++) {
    Core.idct(outplanes.get(k), ioutplanes.get(k));
}
Core.merge(ioutplanes, trans);

这时候得到这个异​​常：

This time got this exception :

的功能/特性尚未实现在虚空CV（奇数大小的DCT的未实现）:: DCT（CV :: InputArray，CV :: OutputArray，INT），文件/ home /报告/ CI / slave_desktop / 50 -SDK / OpenCV的/模块/核心/ src目录/ dxt.cpp，线路2330

这是code正确吗？你的帮助是非常AP preciated。

Is this code correct? Your help is very much appreciated.

更新：我注意到copyMakeBorder（）是导致我的图像大小为奇数的人，这就是为什么我有这个例外

Updated: I noticed that the copyMakeBorder() is the one that caused my image size to be odd, that is why I am having this exception.

推荐答案

也许你可以改变这个code

Maybe you can change this code

int m = Core.getOptimalDFTSize(image.rows());
int n = Core.getOptimalDFTSize(image.cols());

到

int m =Core.getOptimalDFTSize((image.rows()+1)/2)*2;
int n = Core.getOptimalDFTSize((image.cols()+1)/2)*2;

为了获得DCT奇数大小，因为该功能是用于DFT

in order to get the odd size for DCT, since this function is for DFT.

这是写的函数文档从网站，这样的：

It is written in the function documentation from the website as this:

虽然功能不能直接用于估计的最优矢量大小为DCT变换（因为当前的DCT实现支持仅偶数大小的载体）时，它可以很容易地处理为getOptimalDFTSize（（vecsize + 1）/ 2）* 2。

While the function cannot be used directly to estimate the optimal vector size for DCT transform (since the current DCT implementation supports only even-size vectors), it can be easily processed as getOptimalDFTSize((vecsize+1)/2)*2.

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