Matlab语法【C++解释】

Question

我需要将代码从 Matlab 移植到 C++。但是，我对语法有很多困惑，谷歌搜索对我没有帮助。

以下是读取图像文件的代码sn-p。请解释一下 [height width] 和 VolData(:, :, i) 在 C++ 术语中的用途和方式。

%% read images
clc
clear all
cd ('..\STLBP_Matlab\test\'); % please replace "..." by your images path
a = dir('*.jpg'); % directory of images, ".jpg" can be changed, for example, ".bmp" if you use
for i = 1 : length(a)
    ImgName = getfield(a, {i}, 'name');
    Imgdat = imread(ImgName);
    if size(Imgdat, 3) == 3 % if color images, convert it to gray
        Imgdat = rgb2gray(Imgdat);
    end
    [height width] = size(Imgdat);
    if i == 1
        VolData = zeros(height, width, length(a));
    end
    VolData(:, :, i) = Imgdat;
end
cd ..

非常感谢您。

Answer 1

代码只是从一个文件夹中读取一堆 JPEG 图像（大小都相同），将它们转换为灰度图像，然后沿三维堆叠图像以构建我认为的体积数据数组。这个数组的大小是高×宽×N，其中 N 是图像的数量。

在 C/C++ 中，您只需分配一个该大小的缓冲区数组，然后一个接一个地复制每个图像的像素（按行优先顺序，因为这是 C 中的约定）。您可以使用memcpy 之类的方式有效地做到这一点。

Answer 2

此代码似乎将一些图像转换为灰度。这里有一些内联 cmets，但请注意这在语法上是不正确的。您将需要一些最有可能加载 jpeg 并获取将更改语法的原始数据的图像处理库。

a = dir('*.jpg'); % directory of images, ".jpg" can be changed, for example, ".bmp" if you use
%% we are going to loop through all of the images in this directory
for i = 1 : length(a)

    %% give me the name of the current file to process
    ImgName = getfield(a, {i}, 'name');


    %% give me the image data of the first file to process
    Imgdat = imread(ImgName);

    %% if this is an rgb image convert it to gray scale
    if size(Imgdat, 3) == 3 % if color images, convert it to gray
        Imgdat = rgb2gray(Imgdat);
    end

    %% this is a tuple. in c++ there are no tuples
    %% so it would look like this
    %% height = size(ImgData).height;
    %% width = size(ImgData).with;
    [height width] = size(Imgdat);

    %% if this is the very first object create a 3 dimensional array large enough
    %% to hold all of the images, think of it as a stack of length(a) images
    %% of a constant width and height
    if i == 1
        VolData = zeros(height, width, length(a));
    end


    %% copy all of the image data into the vol data field.
    %% this is a vector function. it's really not something in the c++ syntax
    %% in c++ this would likely be nested loops or memcopy as Amro says
    %%  int fileNumb = fileCounter++;
    %%  for (int i =0 ; i < height;i++)
    %%    for (int j=0; j < width; j++)
    %%        somearry[i][j][fileNum] = ImgData[i][j];
    VolData(:, :, i) = Imgdat;
end