如何将灰度Matplotlib图保存到numpy数组 [英] How to save a greyscale matplotlib plot to numpy array

问题描述

例如，我使用matplotlib绘制图形，如下所示:

For example, I plot a figure using matplotlib as follows:

plt.figure(figsize=(10,10))
plt.imshow(output_fig, zorder=0,cmap="gray")
plt.scatter(x,y,color='k')

如果我使用:

plt.savefig(figname,fotmat=figtype)

我将其另存为图形文件.但是，我希望将其保存到矩阵或numpy数组中，以便每个元素都保存图形中每个像素的比例值.我怎样才能做到这一点?我找到了保存RGB值的解决方案.但是我希望保存一个灰度图.谢谢大家的帮助！

I will save it as a figure file. However, I want so save it to a matrix, or numpy array, such that each element saves the scale value of each pixel of the figure. How can I do this? I find solutions saving the RGB values. But I hope to save a greyscale figure. Thank you all for helping me!

推荐答案

一旦有了绘制的数据(下面是自包含的示例):

Once you have a ploted data (self contained example bellow):

import numpy as np
import matplotlib.pyplot as plt
from skimage import data, color

img = data.camera()

x = np.random.rand(100) * img.shape[1]
y = np.random.rand(100) * img.shape[0]

fig = plt.figure(figsize=(10,10))
plt.imshow(img,cmap="gray")
plt.scatter(x, y, color='k')
plt.ylim([img.shape[0], 0])
plt.xlim([0, img.shape[1]])

可以使用 fig.canvas (matplotlib的画布)将基础数据恢复为数组.首先触发其绘制:

The underlying data can be recovered as array by using fig.canvas (the matplotlib's canvas). First trigger its drawing:

fig.canvas.draw()

获取数据作为数组:

width, height = fig.get_size_inches() * fig.get_dpi()
mplimage = np.fromstring(fig.canvas.tostring_rgb(), dtype='uint8').reshape(height, width, 3)

如果您希望数组与原始图像具有相同的形状，则必须使用 plt.figure()的 figsize 和 dpi 属性进行播放.

If you want your array to be the same shape as the original image you will have to play with figsize and dpi properties of plt.figure().

最后，如果需要灰度，matplotlib将返回RGB图像:

Last, matplotlib returns an RGB image, if you want it grayscale:

gray_image = color.rgb2gray(mplimage)

这篇关于如何将灰度Matplotlib图保存到numpy数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！