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import struct, zlib, sys
class image:
w = 0
h = 0
data = []
def read_tga(f):
image = f.read()
img_type = struct.unpack("<B", image[2:3])[0]
img_bpp = struct.unpack("<B", image[16:17])[0]
img_width = struct.unpack("<H", image[12:14])[0]
img_height = struct.unpack("<H", image[14:16])[0]
if img_type != 2 or img_bpp != 32:
print "image must be a RGBA"
start = 18+struct.unpack("B", image[0])[0]
end = start + img_width*img_height*4
image_data = image[start:end] # fetch raw data
return image_data
def write_tga(f, w, h, bpp, data):
f.write(struct.pack("<BBBHHBHHHHBB", 0, 0, 2, 0, 0, 0, 0, 0, w, h, bpp, 0) + data)
def load_png(f):
def read(fmt): return struct.unpack("!"+fmt, f.read(struct.calcsize("!"+fmt)))
def skip(count): f.read(count)
# read signature
if read("cccccccc") != ('\x89', 'P', 'N', 'G', '\r', '\n', '\x1a', '\n'):
return 0
# read chunks
width = -1
height = -1
imagedata = ""
while 1:
size, id = read("I4s")
if id == "IHDR": # read header
width, height, bpp, colortype, compression, filter, interlace = read("IIBBBBB")
if bpp != 8 or compression != 0 or filter != 0 or interlace != 0 or (colortype != 2 and colortype != 6):
print "can't handle png of this type"
print width, height, bpp, colortype, compression, filter, interlace
return 0
skip(4)
elif id == "IDAT":
imagedata += f.read(size)
skip(4) # read data
elif id == "IEND":
break # we are done! \o/
else:
skip(size+4) # skip unknown chunks
# decompress image data
rawdata = map(ord, zlib.decompress(imagedata))
# apply per scanline filters
pitch = width*4+1
bpp = 4
imgdata = []
prevline = [0 for x in xrange(0, (width+1)*bpp)]
for y in xrange(0,height):
filter = rawdata[pitch*y]
pixeldata = rawdata[pitch*y+1:pitch*y+pitch]
thisline = [0 for x in xrange(0,bpp)]
def paeth(a, b, c):
p = a + b - c
pa = abs(p - a)
pb = abs(p - b)
pc = abs(p - c)
if pa <= pb and pa <= pc:
return a
if pb <= pc:
return b
return c
if filter == 0: f = lambda a,b,c: 0
elif filter == 1: f = lambda a,b,c: a
elif filter == 2: f = lambda a,b,c: b
elif filter == 3: f = lambda a,b,c: (a+b)/2
elif filter == 4: f = paeth
for x in xrange(0, width*bpp):
thisline += [(pixeldata[x] + f(thisline[x], prevline[x+bpp], prevline[x])) % 256]
prevline = thisline
imgdata += thisline[4:]
raw = ""
for x in imgdata:
raw += struct.pack("B", x)
#print len(raw), width*height*4
write_tga(file("test2.tga", "w"), width, height, 32, raw)
return 0
load_png(file("butterfly2.png", "rb"))
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