使用matplotlib绘制的图像未显示颜色条

Question

I have a .fit file. I have read the file, displayed the image with scale. When I want to write this image in .png file, the .png file is displaying the image without scale. I am attaching the code that I have tried.

import pyfits
import matplotlib
import matplotlib.pyplot as plt
%matplotlib inline

hdulist = pyfits.open('HMI20170425_134641_6173.fits')
image_data = hdulist[0].data
hdulist.close()
fig=plt.imshow(image_data, cmap='gray')
plt.colorbar()
fig.write_png('image.png')

It is showing output image with scale. However, the 'image.png' file showing image without scale. Please help me in this regard.

Answer 1

I guess what you call the scale is actually the colorbar ? Which indeed is missing when you use fig.write_png because here you are saving only the image part of the plot. You should use plt.savefig instead:

# use astropy instead of pyfits which is no more maintained
import astropy.io.fits as pyfits 

import matplotlib.pyplot as plt
%matplotlib inline

image_data = pyfits.getdata('HMI20170425_134641_6173.fits')
plt.imshow(image_data, cmap='gray')
plt.colorbar()
plt.savefig('image.png')