python - 如何在图像之间传递像素颜色和位置

Question

我试图说明这张图片中的要点:

data.png

并将它们转移到此美国 map 轮廓上:

us_outline.png

但是我在努力。

我正在尝试使用一种方法，在该方法中，我从'data.png'中读取非绿色像素的颜色和坐标位置，并将它们存储在列表中，然后根据其像素将这些像素放置到'us_outline.png'中位置。

这是我到目前为止的代码:

#IMPORTS
from __future__ import division
import math
import numpy as np
from PIL import Image
import matplotlib.pyplot as mplot

#List of pixels from data.png
pixels = []

height = 140
width = 200

#Read in data from data.png
data = Image.open( "data.png" )
data = data.convert('RGB')

for row in range(0,height): #loops over the number of rows in the image
    for col in range(0,width): # loops over the number of columns in the current row
        r,g,b = data.getpixel((row,col))
        rgb = []
        rgb.append(r)
        rgb.append(g)
        rgb.append(b)
        if rgb != [0,255,0]:
            pixels.append(rgb)

但是这样做会导致错误:IndexError:图片索引超出范围

我也尝试过这个:

#Convert to float32 format
data_image = np.float32(data)

#Reads in data points from data.png and appends them to a list
for row in range(len(data_image)): #loops over the number of rows in the image
    for col in range(len(data_image[row])): # loops over the number of columns in the current row
        pixel = data_image[row][col] #Assigns pixel at row and column to a variable
        if pixel != [0,255,0,255]: #If pixel is not green (a.k.a it is a data point)
            pixels.append(pixel) #Set key to the location of pixel and set value to pixel color

#Read in data from us_outline.png     
img2 = Image.open( "us_outline.png" )
usmap = img2.load()
#Convert to float32 format
usmap_image = np.float32(usmap)

#Writes data from pixels list to US map
for row in range(len(usmap_image)): #loops over the number of rows in the image
    for col in range(len(usmap_image[row])): # loops over the number of columns in the current row 
        for pixel in range(len(pixels)):
            if pixels[row][col] == usmap_image[row][col]:
                usmap_image[row][col] = pixels[row][col]

usmap_image = np.uint8( usmap_image ) 

但是这样做会导致第21和22行出现错误

我也尝试过将两个图像简单地加在一起，但是结果很奇怪。

我已经尝试了许多方法，但无法弄清楚如何使其工作。请帮忙!

提前致谢

Answer 1

在第一段代码中，您只需要交换row和col即可正确读取像素。第18行变成

r,g,b = data.getpixel((col, row))

否则，以下代码可以实现您的目标，并且更加简洁:

import numpy as np
import matplotlib.pyplot as plt

# find indices of non-green pixels
data = plt.imread('data.png')
green = np.zeros_like(data)
green[:,:,1] = 1. # plt.imread for some bizarre reason returns rgb values between 0.-1. for the given pngs, not 0-255!
x, y = np.where(np.any(data != green, axis=-1))

# plot non-green pixels on us outline
us = plt.imread('us_outline.png')
us[x,y] = data[x,y]

plt.imshow(us)
plt.show()