Place divisiblesort.py script in same folder as the picture you want to glitch: 'test.jpg'. Delete first line if you are not using Linux. I like the effect best when using one of the recommended divisible numbers... It'll explain. For cross-hatch pixel sort: Sort once, flip image 90 degrees, sort again.

divisiblesort.py

#! /usr/bin/python
import Image


#_______________________________________________________open

source = Image.open("test.jpg")
img = source.load()
print source.format
print source.size
print source.mode
x = source.size[0]
y = source.size[1]


#_______________________________________________________prep pxmap


print "\n...Loading Pixel Map..."
pxmap=[]
j=0
l1=1
while l1==1:
	if j%100==0:
		print j,"/",y
	i=0
	l2=1
	while l2==1:
		r=img[i,j][0]
		g=img[i,j][1]
		b=img[i,j][2]
		ave=(r+g+b)/3
		pxmap.append([ave,r,g,b])
		i=i+1
		if i==x:
			l2=0
	j=j+1
	if j==y:
		l1=0


#_______________________________________________________set divisor

k=1
l1=1
print '\nImage Width Divisible By:  \n[choosing one gives clean vertical lines but is not neccesary]\n[10s to 50s work best]'
while l1==1:
	if x%k==0:
		print "    ",k
	k=k+1
	if k==300:
		l1=0
length = int(raw_input("length:\n>"))


#_______________________________________________________sort

print "\n...Sorting..."
k=0
m=0
a=0
b=length
l1=1
while l1==1:
	if k==20000:
		print b,"/",len(pxmap)
		k=0
	pxmap[a:b] = sorted(pxmap[a:b])
	a=b
	k=k+1
	b=b+length
	if b>=len(pxmap):
		b=len(pxmap)
		l1=0
pxmap = pxmap[0:a] + sorted(pxmap[a:b])
		

#_______________________________________________________apply sort

print "\n...Applying Sort..."
j=0
k=0
l1=1
while l1==1:
	if j%100==0:
		print j,"/",y
	i=0
	l2=1
	while l2==1:
		r=pxmap[k][1]
		g=pxmap[k][2]
		b=pxmap[k][3]			
		img[i,j]=(r,g,b)
		i=i+1
		k=k+1
		if i==x:
			l2=0
	j=j+1
	if j==(y-1):
		l1=0


#_______________________________________________________save

print "\n\n\n\nSaved as divisiblesort.png"
print "\nTurn resulting image 90 degrees and re-run program for cross-hatch sort.  Trust me.  It looks cool.  \n[must rename resulting image to 'test.jpg' or change code to open 'divisiblesort.png'"
source.save("divisiblesort.png")