unshredded Revised

gistfile1.txt

from PIL import Image

PIXEL_DIFF_CONSTANT = 2
IMAGE_HEIGHT = 359
IMAGE_WIDTH = 640
SHRED_WIDTH = 32
PIXEL_IN_COL_TO_SAMPLE = [2,29,40,210,123,122,111,123,190,304] # Automate
NUMBER_OF_COLUMNS = IMAGE_WIDTH/SHRED_WIDTH
FILE = "TokyoPanoramaShredded.png"

# Unshred a shredded image
def unshred():
    image = Image.open(FILE)
    sections = sourceToSections(image)
    ordered_shreds = getOrderedShreds(sections)
    unshredded = orderedShredsToUnShredded(ordered_shreds, image)
    unshredded.save('unshredded.png', 'PNG')

# Class to keep track of unshredded images, right_most_pix_col and left_most_pix_col
class Section(object):
    def __init__(self):
        ordered_shreds = []
        right_most_pixel_col = []
        left_most_pixel_col = []

# Creates a list of section objects from the source image
def sourceToSections(image):
    sections = []
    for i in range(0, NUMBER_OF_COLUMNS):
       section = Section()
       section.ordered_shreds = [i]
       x = i*SHRED_WIDTH
       shred = image.crop((x, 0, x+SHRED_WIDTH-1, IMAGE_HEIGHT))
       section.right_most_pixel_col = getPixelCol(0, shred)
       section.left_most_pixel_col = getPixelCol(SHRED_WIDTH-1, shred)
       sections.append(section)
    return sections

# Get a column of pixel
def getPixelCol(col, shred):
    data = shred.getdata()
    width,height = shred.size
    pixel_col = []
    for i in PIXEL_IN_COL_TO_SAMPLE:
         pixel = data[col*width+i]
         pixel_col.append(pixel)
    return pixel_col

# Return an image from an ordered list
def orderedShredstoUnshredded(ordered_shreds, image):
    unshredded = Image("RGBA", (IMAGE_WIDTH, IMAGE_HEIGHT))
    curr_section = 0
    for i in ordered_shreds:
        x = i*SHRED_WIDTH
        strip = image.crop((x, 0, x+SHRED_WIDTH-1, IMAGE_HEIGHT))
        unshredded.paste(strip, (0,curr_section*SHRED_WIDTH))
        curr_section += 1
    return unshredded

# Returns a list of ordered image columns from a list of sections
def getOrderedShreds(sections):
    while(len(sections)>1):
        sections = mergeSections(sections)
    ordered = sections.pop().ordered_shreds
    return ordered

# Returns a list of sections that are merged as much as possible in one pass
def mergeSections(sections):
    merged_list = sections.pop(0)
    for section in sections:
        merged_list = addSection(section, merged_list)
    return merged_list

# Adds a section into the appropr   iate part of a list or append to end if no match
# Note: could improve to deal with a simultaneous successful right and left match
# currently only handles one match for a given pass through the list
def addSection(section_to_add, merged_list):
    has_match = False
    new_merged_list = []
    for section in merged_list:
        match_type = isSectionMatch(section, section_to_add)
        if(match_type and not has_match): 
            section = mergeSections(section, section_to_add, match_type)    
            has_match = True
        new_merged_list.append(section)
    if not (has_match):
        new_merged_list.append(section_to_add)
    return new_merged_list

# Merge an item on the left or right side of a section and return the adjusted section
def mergeSections(section, item, match_type):
    if(match_type==1):
        section.ordered_shreds = section.ordered_shreds + item.ordered_shreds
        section.right_most_pixel_col = item.right_most_pixel_col
    if(match_type==-1):
        section.ordered_shreds = item.ordered_shreds + section.ordered_shreds
        section.left_most_pixel_col = item.left_most_pixel_col
    return section

# Determine if two sections match and return if right or left match
def isSectionMatch(section_1, section_2):
    if isColumnMatch(section_1.right_most_pixel_col, section_2.left_most_pixel_col):
        return 1
    if isColumnMatch(section_1.left_most_pixel_col, section_2.right_most_pixel_col):
        return -1
    else:
        return 0
        
# Determine if two columns match returns true iff all pixels meet match criteria
def isColumnMatch(col_1, col_2):
    match = True
    for i in PIXEL_IN_COL_TO_SAMPLE:
        match = (isPixelMatch(col_1[i], col_2[i]) & match)
    return match

# Determine if two pixels match
def isPixelMatch(pixel_1, pixel_2):
    if ((abs(pixel_1[0] - pixel_2[0]) < PIXEL_DIFF_CONSTANT) 
    and (abs(pixel_1[1] - pixel_2[1]) < PIXEL_DIFF_CONSTANT)
    and (abs(pixel_1[2] - pixel_2[2]) < PIXEL_DIFF_CONSTANT)
    and (abs(pixel_1[3] - pixel_2[3]) < PIXEL_DIFF_CONSTANT)):
        return true
    else:
        return false