如何将单个像素位置作为 plt.imshow 的参数？

Question

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt

image = Image.open(r'C:\Users\oneblackpixel.png')
image2 = np.asarray(image)

fig = plt.figure()
imgplot = plt.imshow([image2[0][0]])
plt.show()

This code prints purple, when actually the image is black in color and is a singular pixel.

Answer 1

I converted default image pixel values to RGB pallete. Code is shown below:

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt

image = Image.open(r'black_white_image.png')
# image2 = np.asarray(image)
imgRgb = image.convert('RGB')

fig = plt.figure()
plt.imshow(imgRgb)
plt.show()

Answer 2

Here is the code change:

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt

image = Image.open(r'C:\Users\oneblackpixel.png')
image2 = np.asarray(image)

fig = plt.figure()

# need a second bracket here:
imgplot = plt.imshow([[image2[0][0]])
plt.show()

Image is read as a 3-d array. First and second dimension is the x and y axis of image, third dimension is the color info of pixel. In your case, would be [0,0,0,255] if it's black from a .png file. Value in the array is [R,G,B,Alpha] in order. imshow will plot the 4 values from a pixel if you only use 1 bracket.

Answer 3

did you try reading the image as a matplot image? you do it just like:

import matplotlib.image as img
image = img.imread("oneblackpixel.png")

it is usually recommended. also, this line:

imgplot = plt.imshow([image2[0][0]])

turns your image into a 2 dimentional array (which is bad, you will want 3) this will solve that problem:

image2 = [[image[0][0]]]

I also did some cleaning, this code shuld work for you

import matplotlib.pyplot as plt
import matplotlib.image as img
image = img.imread("oneblackpixel.png")

image2 = [[image[0][0]]]

fig = plt.figure()
plt.imshow(image2)
plt.show()

dose that help?