The following minimal example:
import matplotlib
matplotlib.use('Agg')
from astropy.wcs import WCS
from wcsaxes import datasets
import matplotlib.pyplot as plt
hdu = datasets.fetch_msx_hdu()
plt.imshow(hdu.data, vmin=-2e-4, vmax=2e-4)
plt.savefig('image.png')
produces the following output:
This appears to be related to the fact the values in the image data are < 1. If I multiply all the values by 1e6, I get something sensible:
plt.imshow(hdu.data * 1e6, vmin=-2e-4, vmax=2e-4)
plt.savefig('image.png')
The following minimal example:
produces the following output:
This appears to be related to the fact the values in the image data are < 1. If I multiply all the values by 1e6, I get something sensible: