paletteSwap.py

from PIL import Image
import datetime
import random
import os
import copy

def paletteSwap(src, dest, time):
    if os.sep in src:
        srcSplit = src.split(os.sep)
        srcName = srcSplit[len(srcSplit) - 1]
    else:
        srcName = src
    if os.sep in dest:
        destSplit = dest.split(os.sep)
        destName = destSplit[len(destSplit) - 1]
    else:
        destname = dest

    print "Converting " + srcName + " to " + destName

    imSrc = Image.open(src)
    pixSrc = imSrc.load()
    (srcWidth, srcHeight) = imSrc.size
    srcPixels = srcWidth * srcHeight

    imDest = Image.open(dest)
    pixDest = imDest.load()
    (destWidth, destHeight) = imDest.size
    numPixels = destWidth * destHeight
    
    newImage = Image.new("RGB", (destWidth, destHeight))
    pixPallet = newImage.load()

    arr = set(Image.open(src).convert('RGB').getdata())

    
    # Copies the pixels from the source to a new image that has the same
    # dimensions as the destination image
    for i in xrange(numPixels):
        # If there are more pixels in the target image then we iterate through
        # the source image again
        srcX = i % srcWidth
        srcY = (i / srcWidth) % srcHeight

        destX = i % destWidth
        destY = i / destWidth

        pixPallet[destX, destY] = pixSrc[srcX, srcY]

        assert(pixPallet[destX, destY] in arr)

    startTime = datetime.datetime.now()

    # Run the algorithm for the alloted amount of time
    while (datetime.datetime.now() - startTime).total_seconds() < time:
        print "Time Left: " + str(time - ((datetime.datetime.now() - startTime).total_seconds()))
        
        # For each pixel in the created image we check it against 5 random 
        # pixels and out of those 6 pixels if switching it makes it closer to
        # the original image then we swap them
        for x in xrange(destWidth):
            for y in xrange(destHeight):
                sPix = pixPallet[x,y]
                dPix = pixDest[x,y]
                curDelta = getDelta(sPix, dPix)
                newX = x
                newY = y
                for i in xrange(5):
                    randX = random.randint(0, destWidth-1)
                    randY = random.randint(0, destHeight-1)
                    sPixRand = pixPallet[randX,randY]
                    dPixRand = pixDest[randX, randY]
                    delta = getDelta(sPixRand, dPix)
                    if getDelta(sPix, dPixRand) + delta < curDelta + getDelta(sPixRand, dPixRand):
                        curDelta = delta
                        sPix = sPixRand
                        newX = randX
                        newY = randY
                pixPallet[newX, newY] = pixPallet[x,y]
                pixPallet[x,y] = sPix

    # Creates the new image file
    newFile = srcName.split(".")[0] + " to " + destName.split(".")[0] + ".png"
    print newFile
    newImage.save("Created" + os.sep + newFile)
    check(src, "Created" + os.sep + newFile)


# Gets the difference between two pixels using Luma weighting which weighs
# red, green, and blue differently based on brightness since humans notice
# brightness differences much more than they notice color difference 
def getDelta(color1, color2):
    luma = [0.299, 0.587, 0.144]
    diff = 0
    sum1 = 0
    sum2 = 0
    for i in xrange(len(color1)):
        sum1 += color1[i]*luma[i]
        sum2 += color2[i]*luma[i]
        d = (color1[i] - color2[i])*luma[i]
        diff += d*d
    rawDiff = sum1 - sum2
    return diff + rawDiff * rawDiff * 10

# Checks that the final result is actually the same pixels
def check(palette, copy):
    palette = sorted(Image.open(palette).convert('RGB').getdata())
    copy = sorted(Image.open(copy).convert('RGB').getdata())
    if len(palette) == len(copy):
        print "Success" if copy == palette else "Failed"
    elif len(palette) < len(copy):
        print "Success" if set(palette).issubset(set(copy)) else "Failed palette"
    else:
        print "Success" if set(copy).issubset(set(palette)) else "Failed copy"

paletteChange("Original\\Mona Lisa.png","Original\\Balls.png", 150)

# paletteChange("Original\\New York.jpg", "Original\\Chicago.jpg", 150)

# paletteChange("Original\\Chicago.jpg", "Original\\New York.jpg", 150)