def _open(self):

        # HEAD
        s = self.fp.read(512)
        if i16(s) != 474:
            raise SyntaxError("not an SGI image file")

        # relevant header entries
        compression = ord(s[2])

        # bytes, dimension, zsize
        layout = ord(s[3]), i16(s[4:]), i16(s[10:])

        # determine mode from bytes/zsize
        if layout == (1, 2, 1) or layout in (1, 1, 1):
            self.mode = "L"
        elif layout == (1, 3, 3):
            self.mode = "RGB"
        elif layout == (1, 3, 4):
            self.mode = "RGBA"
        else:
            raise SyntaxError("unsupported SGI image mode")

        # size
        self.size = i16(s[6:]), i16(s[8:])


        # decoder info
        if compression == 0:
            offset = 512
            pagesize = self.size[0]*self.size[1]*layout[0]
            self.tile = []
            for layer in self.mode:
                self.tile.append(("raw", (0,0)+self.size, offset, (layer,0,-1)))
                offset = offset + pagesize
        elif compression == 1:
            self.tile = [("sgi_rle", (0,0)+self.size, 512, (self.mode, 0, -1))]

#
# registry
dataset/ETHPy150Open kleientertainment/ds_mod_tools/pkg/win32/Python27/Lib/site-packages/PIL/SgiImagePlugin.py/SgiImageFile._open/operator `==` -> `in`