Question

我有包含图片的文件夹

C:/Users/admin/Downloads/mypicture

这里有几张图片，我需要阅读。我使用library("EBImage")

x <- readImage("C:/Users/admin/Downloads/mypicture")

然后得到错误

Error in readImage("C:/Users/admin/Downloads/mypicture") :
Unable to determine type of C:/Users/admin/Downloads/mypicture: Filename extension missing.

如何一次读取所有图片，然后为每张图片提取像素阵列

# width and height of the original image

dim(x)[1:2]

# scale to a specific width and height

y <- resize(x, w = 200, h = 100)

# scale by 50%; the height is determined automatically so that
# the aspect ratio is preserved

y <- resize(x, dim(x)[1]/2)

# show the scaled image

显示（y）

# extract the pixel array

z <- imageData(y)

如何做到？

这是我文件夹中的两张图片

我需要创建像素阵列

z <- array(y)

像这样，标有图片名称kBFrf.jpg的地方

            [,1]      [,2]      [,3]      [,4]      [,5]      [,6]      [,7]      [,8]      [,9]     [,10]     [,11]     [,12]
  [1,] 0.4676471 0.5000000 0.5382353 0.5803922 0.6107843 0.6441176 0.6715686 0.6843137 0.6901961 0.7117647 0.7303922 0.7362745
  [2,] 0.4735294 0.5078431 0.5441176 0.5745098 0.6186275 0.6392157 0.6774510 0.6882353 0.7127451 0.7245098 0.7500000 0.7764706
  [3,] 0.4735294 0.5039216 0.5470588 0.5892157 0.6186275 0.6539216 0.6764706 0.7049020 0.7225490 0.7343137 0.7637255 0.7862745
           [,13]     [,14]     [,15]     [,16]     [,17]     [,18]     [,19]     [,20]     [,21]     [,22]     [,23]     [,24]
  [1,] 0.7686275 0.7843137 0.8000000 0.8156863 0.8450980 0.8460784 0.8519608 0.8539216 0.8529412 0.8607843 0.8647059 0.8568627
  [2,] 0.8049020 0.8274510 0.8392157 0.8745098 0.8843137 0.8892157 0.8960784 0.8882353 0.8911765 0.9009804 0.8950980 0.8872549
  [3,] 0.8058824 0.8303922 0.8558824 0.8735294 0.8784314 0.8901961 0.8911765 0.8882353 0.8794118 0.8823529 0.8803922 0.8852941

-

69onL.jpg

      [,1]      [,2]      [,3]      [,4]      [,5]      [,6]      [,7]      [,8]      [,9]     [,10]     [,11]     [,12]
  [1,] 0.4676471 0.5000000 0.5382353 0.5803922 0.6107843 0.6441176 0.6715686 0.6843137 0.6901961 0.7117647 0.7303922 0.7362745
  [2,] 0.4735294 0.5078431 0.5441176 0.5745098 0.6186275 0.6392157 0.6774510 0.6882353 0.7127451 0.7245098 0.7500000 0.7764706
  [3,] 0.4735294 0.5039216 0.5470588 0.5892157 0.6186275 0.6539216 0.6764706 0.7049020 0.7225490 0.7343137 0.7637255 0.7862745
           [,13]     [,14]     [,15]     [,16]     [,17]     [,18]     [,19]     [,20]     [,21]     [,22]     [,23]     [,24]
  [1,] 0.7686275 0.7843137 0.8000000 0.8156863 0.8450980 0.8460784 0.8519608 0.8539216 0.8529412 0.8607843 0.8647059 0.8568627
  [2,] 0.8049020 0.8274510 0.8392157 0.8745098 0.8843137 0.8892157 0.8960784 0.8882353 0.8911765 0.9009804 0.8950980 0.8872549
  [3,] 0.8058824 0.8303922 0.8558824 0.8735294 0.8784314 0.8901961 0.8911765 0.8882353 0.8794118 0.8823529 0.8803922 0.8852941

如何创建此类数据框

带数字的图片的结果

       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13] [,14] [,15] [,16] [,17]     [,18]     [,19]
  [1,]    1    1    1    1    1    1    1    1    1     1     1     1     1     1     1     1     1 1.0000000 1.0000000
  [2,]    1    1    1    1    1    1    1    1    1     1     1     1     1     1     1     1     1 1.0000000 1.0000000
            [,20]      [,21]       [,22]       [,23]       [,24]       [,25]       [,26]       [,27]       [,28]       [,29]
  [1,] 1.00000000 1.00000000 1.000000000 1.000000000 1.000000000 1.000000000 1.000000000 1.000000000 1.000000000 1.000000000

Answer 1

readImage函数将文件名的向量作为输入，因此，要从目录中读取所有图像，您需要列出其内容

library(EBImage)

# create a vector of file names
fls <- dir("./img", full.names = TRUE)

# read images
imgs <- readImage(fls, 'png')

# display images
display(imgs, method = 'raster', all = TRUE)

图像数据存储在Image类中，该类内部保存着一个array

# internal representation of images data
y <- class(imageData(imgs))

# dimensions of image stack
dim(imgs)
## [1] 825 825   4  10

前两个尺寸对应于XY尺寸，第三个尺寸保持颜色通道（在这种情况下为RGBA），最后一个尺寸是单个图像。为了提取单个图像，例如第二个图像，请使用

img <- getFrame(imgs, 2, "render")

如果您想使用图像的原始名称来引用图像，则可以使用类似于以下内容的方法。

# mapping of file names to frame indices
idx <- setNames(1:length(fls), basename(fls))

getFrame(imgs, idx['sample.png'], "render")

将图片转换为R中的像素数据帧（EBImage lib）

1 个答案: