Uncrop a sequence of Cropped TIFFs

uncrop.py

#!/usr/bin/env python
# Public Domain

"""
Uncrop a sequence of Cropped TIFFs[1] generated by Hugin, nona or
PTmender.

Pad images with transparent background to the minimum common extent
according to XPosition, YPosition tags. Images are save to uncrop/
subdirectory.

Requirements: tiffdump and convert utilities.

[1]: http://wiki.panotools.org/Cropped_TIFF
"""

from sys import argv, exit
from os import popen, system, path, environ

OUTPUT_DIR = "uncrop/"

def usage():
    print path.basename(argv[0]), " image.tiff [image.tiff ...]"
    print __doc__

def readtags(tiff):

    def readtag(fields):
        name = fields[0]
        type_ = fields[3]
        types = { "(1)": int, # BYTE
                  "(2)": chr, # ASCII
                  "(3)": int, # SHORT
                  "(4)": int, # LONG
                  "(5)": float # RATIONAL
                }
        readfn = types.get(type_, lambda x:x)
        vals = fields[-1].strip()
        vals_ = [ s for s in vals[vals.find("<")+1:-1].split()]
        vals = map(readfn, vals_)
        val = vals[0] if len(vals) == 1 and (type_ in types.keys()) else vals
        return (name,val)

    lines = [ ln.strip().split(" ", 4)
              for ln in popen("tiffdump '%s'" % tiff).readlines()[3:] ]
    tags = [ readtag(ln) for ln in lines ]
    return dict(tags)

def extent_px(tagged_pairs):
    tops = []
    lefts = []
    bottoms = []
    rights = []
    for img,tags in tagged_pairs:
        xpos = tags["XPosition"]
        ypos = tags["YPosition"]
        xdpi = tags["XResolution"]
        ydpi = tags["YResolution"]
        w = tags["ImageWidth"]
        h = tags["ImageLength"]
        l = int(round(xpos*xdpi))
        t = int(round(ypos*ydpi))
        tops.append(t)
        lefts.append(l)
        bottoms.append(t+h)
        rights.append(l+w)
    return ((min(lefts), min(tops)), (max(rights),max(bottoms)))

def geom(extent):
    (x0,y0), (x1,y1) = extent
    w = x1-x0
    h = y1-y0
    return (w,h)

def repage(image, tags, newgeom, newimage):
    W, H = newgeom
    xpos = tags["XPosition"]
    ypos = tags["YPosition"]
    xdpi = tags["XResolution"]
    ydpi = tags["YResolution"]
    w = tags["ImageWidth"]
    h = tags["ImageLength"]
    l = int(round(xpos*xdpi))
    t = int(round(ypos*ydpi))
    ext1 = "%dx%d" % (w+l, h+t)
    ext2 = "%dx%d" % (W, H)
    cmd = "convert '%s' -background none -gravity southeast -extent %s -gravity northwest -extent %s '%s'" % (image, ext1, ext2, newimage)
    print cmd
    system(cmd)


images = argv[1:]
if not images:
    usage()
    exit(0)

tagged = [ (img, readtags(img)) for img in images ]
geom = geom(extent_px(tagged))
for img, tags in tagged:
    repage(img, tags, geom, OUTPUT_DIR + img)