如何使用R从图像获取像素数据
任何人都可以帮助我如何从R中的图像获取RGB像素数据
Can anyone help me on how to get the RGB pixel data from an image in R?
我需要这个信息来比较鸟羽毛的差异，以帮助
I need this information to compare differences in bird plumage to aid in the understanding of a speciation event.
我的照片由数码相机拍摄，现在作为NEF文件。无论需要哪种类型的文件，我都可以将文件转换为我想要的文件。然而，我更喜欢在文件中保持尽可能多的信息（即PNG文件是好的）。
My photos are taken by a digital camera and are now as a NEF-file. It doesn't matter which type of file that's needed, I have the possibility to convert the file to whatever I want. However, I would prefer to maintain as much information as possible in the file (i. e. PNG-files are good).
我在R：Pixmap，Raster，ImageMetrics中尝试过许多软件包，并浏览了互联网，测试方法，问同事等几个星期试图解决这个问题。
这里在Stackoverflow我试过这个：如何提取像素数据使用R的像素映射包？，没有运气。我的文件对于R窗口也太大了（整个数组不显示），我很难理解产生的数组。对我来说最好的事情是把数据作为一个矩阵或者另一种方式，使得更容易理解什么是什么。
我发现了类似的问题，但在其他程序（如Java，C ++，IOS，Matlab，Python等），我不幸不知道如何使用。
I have tried many packages in R: Pixmap, Raster, ImageMetrics and browsed the internet, tested methods, asked co-students etc. for several weeks trying to solve this problem. Here at Stackoverflow I've tried this: How to extract the pixel data Use R's pixmap package?, with no luck. My files are also too big for the R window (the entire array doesn't show), and I have difficulties understanding the array produced. The best thing for me would be to get the data as a matrix or in another way that makes it easier to understand what is what. I have found loads of similar questions, but in other programs (such as Java, C++, IOS, Matlab, Python etc) which I unfortunately don't know how to use.
我的问题可能是由于我这种类型的工作的低技能，但我正在努力，我可以与我的背景。
如果任何人可以帮助我或给我一些提示，我将非常感激。
My problems might be due to my low skills with this type of work, but I am trying as hard as I can with the background that I have. If anyone can help me or give me som tips, I will be very grateful.
示例 png image：
png("/tmp/test.png")
plot(rnorm(100))
dev.off()
然后我将其转换为 pixmap 可读的格式：这里我将png转换为ppm文件，因为我想保留颜色信息。我从命令行使用ImageMagick，但你可以使用任何你想要的程序：
Then I convert it to a format readable by pixmap : here I convert the png to a ppm file as I want to keep colors information. I use ImageMagick from the command line, but you can use whatever program you want :
$ convert /tmp/test.png /tmp/test.ppm
接下来，您可以使用 函数： pixmap 软件包中的.pnm
Next, you can read the image with the read.pnm function from the pixmap package :
x <- read.pnm("/tmp/test.ppm")
，您可以使用 x @ red ， x @ blue ， x @ green 插槽（或对于灰度图像，或 x @ gray ），以获取每个通道的像素值作为矩阵。您可以检查矩阵的尺寸是否与图片大小相同：
And then, you can use the x@red, x@blue, x@green slots (or x@grey for a greyscale image) to get the pixels value for each channel as a matrix. You can check that the dimensions of the matrices are the same as the size of your picture :
dim(x@red)
[1] 480 480