告诉我下面代码的作用和意义: [row, col] = size(gray_img); data = reshape(gray_img, row * col, 1); k = 3; [idx, ~] = kmeans(data, k); idx = reshape(idx, row, col);
时间: 2024-03-31 12:37:22 浏览: 22
这段代码的作用是对灰度图像进行聚类操作,将像素点分为 k 类,并将每个像素点的类别标签存储在一个和原图像尺寸相同的矩阵 idx 中。
具体的实现过程如下:
1. 获取灰度图像的大小,即行数和列数,存储在变量 row 和 col 中。
2. 将灰度图像 gray_img 通过 reshape 函数变为一列数据,存储在变量 data 中。
3. 执行 k-means 算法,将 data 中的数据分为 k 类,并将每个数据所属的类别标签存储在变量 idx 中。
4. 将 idx 通过 reshape 函数变为和原图像灰度图像大小相同的矩阵,存储在变量 idx 中。
最终,idx 矩阵中的每个元素表示原图像中对应位置的像素点所属的类别。
相关问题
function [one_feat_sps, weight_pool_info]=do_sp_pooling(one_feat_img, one_sp_info) img_size=size(one_feat_img); num_units=img_size(1)*img_size(2); dim=img_size(3); one_feat_img=reshape(one_feat_img, [num_units dim]); img_size_org=one_sp_info.img_size; pixel_ind_map=reshape([1: num_units], [img_size(1) img_size(2)]); pixel_ind_map_org=imresize(pixel_ind_map, img_size_org, 'nearest'); pixel_ind_sps=one_sp_info.pixel_ind_sps; num_sp=numel(pixel_ind_sps); weight_pool_info=zeros([num_sp, num_units], 'like', one_feat_img); for idx_sp=1:num_sp pixel_ind_sp_one=pixel_ind_sps{idx_sp}; ind_pixels_in_map=pixel_ind_map_org(pixel_ind_sp_one); [ind_units,~,uniqueIndex] = unique(ind_pixels_in_map); frequency = accumarray(uniqueIndex(:),1)./numel(ind_pixels_in_map); frequency=single(frequency); freq_one_sp=zeros(1, num_units, 'single'); freq_one_sp(ind_units)=frequency; weight_pool_info(idx_sp, :)=freq_one_sp; end one_feat_sps=weight_pool_info*one_feat_img; end将上述代码转换为pytorch代码,并可视化超像素的索引】
以下是将给定的 MATLAB 代码转换为 PyTorch 代码的过程:
```
import torch
import torch.nn.functional as F
import numpy as np
from scipy import ndimage
def do_sp_pooling(one_feat_img, one_sp_info):
img_size = one_feat_img.shape
num_units = img_size[0] * img_size[1]
dim = img_size[2]
one_feat_img = one_feat_img.reshape(num_units, dim)
img_size_org = one_sp_info['img_size']
pixel_ind_map = np.arange(num_units).reshape(img_size[0], img_size[1])
pixel_ind_map_org = ndimage.zoom(pixel_ind_map, [img_size_org[0]/img_size[0], img_size_org[1]/img_size[1]], order=0)
pixel_ind_sps = one_sp_info['pixel_ind_sps']
num_sp = len(pixel_ind_sps)
weight_pool_info = torch.zeros((num_sp, num_units), dtype=one_feat_img.dtype, device=one_feat_img.device)
for idx_sp in range(num_sp):
pixel_ind_sp_one = pixel_ind_sps[idx_sp]
ind_pixels_in_map = pixel_ind_map_org[pixel_ind_sp_one]
_, uniqueIndex = np.unique(ind_pixels_in_map, return_inverse=True)
frequency = np.bincount(uniqueIndex) / len(ind_pixels_in_map)
frequency = frequency.astype(one_feat_img.dtype)
freq_one_sp = torch.zeros(num_units, dtype=one_feat_img.dtype, device=one_feat_img.device)
freq_one_sp[ind_pixels_in_map] = torch.tensor(frequency, dtype=one_feat_img.dtype, device=one_feat_img.device)
weight_pool_info[idx_sp, :] = freq_one_sp
one_feat_sps = torch.mm(weight_pool_info, one_feat_img)
return one_feat_sps, weight_pool_info
```
这里我们使用了 PyTorch 库中的相关函数来实现对应功能,同时为了可视化超像素的索引,我们可以在函数中增加一些代码:
```
def do_sp_pooling(one_feat_img, one_sp_info):
img_size = one_feat_img.shape
num_units = img_size[0] * img_size[1]
dim = img_size[2]
one_feat_img = one_feat_img.reshape(num_units, dim)
img_size_org = one_sp_info['img_size']
pixel_ind_map = np.arange(num_units).reshape(img_size[0], img_size[1])
pixel_ind_map_org = ndimage.zoom(pixel_ind_map, [img_size_org[0]/img_size[0], img_size_org[1]/img_size[1]], order=0)
pixel_ind_sps = one_sp_info['pixel_ind_sps']
num_sp = len(pixel_ind_sps)
weight_pool_info = torch.zeros((num_sp, num_units), dtype=one_feat_img.dtype, device=one_feat_img.device)
for idx_sp in range(num_sp):
pixel_ind_sp_one = pixel_ind_sps[idx_sp]
ind_pixels_in_map = pixel_ind_map_org[pixel_ind_sp_one]
_, uniqueIndex = np.unique(ind_pixels_in_map, return_inverse=True)
frequency = np.bincount(uniqueIndex) / len(ind_pixels_in_map)
frequency = frequency.astype(one_feat_img.dtype)
freq_one_sp = torch.zeros(num_units, dtype=one_feat_img.dtype, device=one_feat_img.device)
freq_one_sp[ind_pixels_in_map] = torch.tensor(frequency, dtype=one_feat_img.dtype, device=one_feat_img.device)
weight_pool_info[idx_sp, :] = freq_one_sp
# 可视化超像素的索引
img_sp = np.zeros_like(pixel_ind_map_org)
img_sp[pixel_ind_sp_one//img_size[1], pixel_ind_sp_one%img_size[1]] = 1
img_sp = ndimage.binary_dilation(img_sp, iterations=1)
img_sp = np.where(img_sp, idx_sp+1, 0)
img_sp = ndimage.zoom(img_sp, [img_size[0]/img_size_org[0], img_size[1]/img_size_org[1]], order=0)
plt.imshow(img_sp, cmap='jet', alpha=0.3, vmin=0, vmax=num_sp)
one_feat_sps = torch.mm(weight_pool_info, one_feat_img)
return one_feat_sps, weight_pool_info
```
这里我们使用 matplotlib 库来绘制可视化结果,以 jet 颜色映射来表示超像素的索引。
解释如下代码:def read_sample(input_file,input_size, sample_ind,T_ind,H_ind): tt= input_size[input_size.testB_SAM_ID == sample_ind] pos = tt.start_pos.values[0] row = tt.N_row.values[0] col= tt.N_col.values[0] TH_ind = (T_ind-1)*4 + (H_ind - 1) f = open(input_file, "r") f.seek( pos + TH_ind*row*col , os.SEEK_SET) # seek data = np.fromfile( f, count = row*col, dtype = np.ubyte) f.close() data_mat = data.reshape(row,col) return data_mat
这段代码定义了一个函数`read_sample`,它接受四个参数`input_file`、`input_size`、`sample_ind`、`T_ind`和`H_ind`。
函数的主要作用是从文件中读取一个样本,并将其转换成一个二维数组返回。`input_size`是一个包含样本尺寸信息的数据框。
函数中的第二行代码从`input_size`中获取样本`sample_ind`的尺寸信息,包括起始位置`pos`、行数`row`和列数`col`。这些信息将用于从文件中读取样本数据。
接下来,函数将列索引`T_ind`和`H_ind`转换成一个一维索引`TH_ind`,这个索引表示在每个样本中,目标区域的起始位置(目标区域是以`T_ind`和`H_ind`为中心的4x4正方形)。
然后,函数打开指定的文件,并使用`seek`方法将文件指针移动到目标区域的起始位置。`seek`方法的参数是一个字节数,计算方法为`pos + TH_ind*row*col`,其中`pos`是样本在文件中的起始位置,`row`和`col`是样本的行数和列数,`TH_ind`是目标区域的起始位置(以像素为单位)。
接下来,函数使用`numpy`库中的`fromfile`方法读取指定数量的字节,并将其解释为一个无符号字节数组。这个数组中的每个元素代表一个像素的灰度值。
最后,函数使用`reshape`方法将一维数组转换为一个二维数组,并将其返回。