matplotlib example split sdss jpeg (snippet)

Python matplotlib example 'split sdss jpeg'

Functions in program:

def main():
def save_images(filename,outname):
def split_image(filename):
def make_color_maps():

Modules used in program:

import pylab as pl
import numpy as np
import matplotlib
import PIL.Image

python split sdss jpeg

Python matplotlib example: split sdss jpeg

import PIL.Image
import matplotlib
matplotlib.use("Agg")
import numpy as np
import pylab as pl

def make_color_maps():
    x=np.arange(0.,1.,0.01)
    z=np.zeros_like(x)
    R=list(zip(x,z,z))
    G=list(zip(z,x,z))
    B=list(zip(z,z,x))
    red=matplotlib.colors.ListedColormap(R,name='BlackRed')
    green=matplotlib.colors.ListedColormap(G,name='BlackGreen')
    blue=matplotlib.colors.ListedColormap(B,name='BlackBlue')
    return red,green,blue

red_colormap,green_colormap,blue_colormap = make_color_maps()

def split_image(filename):
    image=np.asarray(PIL.Image.open(filename))
    g_filter=image[:,:,0]
    r_filter=image[:,:,1]
    i_filter=image[:,:,2]
    return g_filter,r_filter,i_filter

def save_images(filename,outname):
    g,r,i=split_image(filename)
    for filter,name,cm in zip([g,r,i],['g','r','i'],[red_colormap,green_colormap,blue_colormap]):
        pl.figure(frameon=False)
        pl.imshow(filter,cmap=cm)
        ax=pl.gca()
        ax.set_axis_off()
        pl.savefig(outname+"_"+name+".png")
        pl.close()

def main():
    import sys
    input,output=sys.argv[1],sys.argv[2]
    save_images(input,output)


if __name__=="__main__":
    main()

Python links

Learn Python: https://pythonbasics.org/
Python Tutorial: https://pythonprogramminglanguage.com