Minified version of pnger.py at https://gist.github.com/rocket-pig/c8e29296fa7f462d7fd8e8fe642ad5c2

minipnger.py

Q='RGB'
P=True
O='rb'
N=chr
L=bytes
K=float
G=range
I=open
C=print
F=int
E=len
import math as B
from PIL import Image as H
import sys as A
if E(A.argv)<2:C('Usage: %s <input file> <output file>'%A.argv[0]);C('if <input file> is a file, will convert to png.');C('if <input file> is a png, will convert back to file');A.exit(1)
def M(infile):
	with I(infile,O)as C:D=C.read()
	G=E(D);H=F(B.ceil(K(G)/3.0));J=B.sqrt(H);A=F(B.ceil(J));return A,A
def D(infile,outfile,no_progress=P,verbose=False):
	F=no_progress;C=outfile;D=H.open(infile)
	with I(C,'wb')as C:
		M=D.convert(Q);B=0
		for J in G(D.size[1]):
			if not F:O=K((J+1)//D.size[1]*100);A.stderr.write('\r%s%s'%(round(O,2),'%'))
			for P in G(D.size[0]):
				R=M.getpixel((P,J))
				for E in R:
					if E==0:B+=1
					else:
						if B!=0:
							for T in G(B):
								if A.version_info.major>=3:C.write(L([0]))
								else:C.write(N(0))
							B=0
						if A.version_info.major>=3:C.write(L([E]))
						else:C.write(N(E))
		if not F:A.stderr.write('\n')
		if B!=0 and verbose:
			S=B
			if S==1:A.stderr.write('Omitting %s zero from end of file\n'%B)
			else:A.stderr.write('Omitting %s zeroes from end of file\n'%B)
def J(infile,outfile):
	J=infile;K=I(J,O);L=M(J);N=F(L[0]),F(L[1]);A=H.new(Q,N);R=A.load();C=0;D=-1
	while P:
		B=K.read(3)
		if not B:break
		D+=1
		if D>=A.size[0]:
			D=0;C+=1
			if C>=A.size[1]:raise Exception('Error: row %s is greater than maximum rows in image, %s.'%(C,A.size[1]))
		G=[B[0],0,0]
		if E(B)>1:G[1]=B[1]
		if E(B)>2:G[2]=B[2]
		if not C>=A.size[1]:R[(D,C)]=tuple(G)
	A.save(outfile,format='PNG');K.close()
if __name__=='__main__':
	if A.argv[1].endswith('.png'):D(A.argv[1],A.argv[2])
	else:J(A.argv[1],A.argv[2])