from?PIL?import?Image
from?numpy?import?*
from?pylab?import?*
import?os

def?process_image（imagenameresultnameparams=“--edge-thresh?10?--peak-thresh?5“）:
????“““?Process?an?image?and?save?the?results?in?a?file.?“““

????if?imagename[-3:]?!=?‘pgm‘:
????????#?create?a?pgm?file
????????im?=?Image.open（imagename）.convert（‘L‘）
????????im.save（‘tmp.pgm‘）
????????imagename?=?‘tmp.pgm‘

????cmmd?=?str（“E:\Python-PCV\VLFeat\win64\sift.exe?“+imagename+“?--output=“+resultname+
????????????????“?“+params）
????os.system（cmmd）
????print?‘processed‘?imagename?‘to‘?resultname


def?read_features_from_file（filename）:
????“““?Read?feature?properties?and?return?in?matrix?form.?“““
????
????f?=?loadtxt（filename）
????return?f[::4]f[:4:]?#?feature?locations?descriptors


def?write_features_to_file（filenamelocsdesc）:
????“““?Save?feature?location?and?descriptor?to?file.?“““
????savetxt（filenamehstack（（locsdesc）））
????

def?plot_features（imlocscircle=False）:
????“““?Show?image?with?features.?input:?im?（image?as?array）?
????????locs?（row?col?scale?orientation?of?each?feature）.?“““

????def?draw_circle（cr）:
????????t?=?arange（01.01.01）*2*pi
????????x?=?r*cos（t）?+?c[0]
????????y?=?r*sin（t）?+?c[1]
????????plot（xy‘b‘linewidth=2）

????imshow（im）
????if?circle:
????????for?p?in?locs:
????????????draw_circle（p[:2]p[2]）?
????else:
????????plot（locs[:0]locs[:1]‘ob‘）
????axis（‘off‘）


def?match（desc1desc2）:
????“““?For?each?descriptor?in?the?first?image?
????????select?its?match?in?the?second?image.
????????input:?desc1?（descriptors?for?the?first?image）?
????????desc2?（same?for?second?image）.?“““
????
????desc1?=?array（[d/linalg.norm（d）?for?d?in?desc1]）
????desc2?=?array（[d/linalg.norm（d）?for?d?in?desc2]）
????
????dist_ratio?=?0.6
????desc1_size?=?desc1.shape
????
????matchscores?=?zeros（（desc1_size[0]）‘int‘）
????desc2t?=?desc2.T?#?precompute?matrix?transpose
????for?i?in?range（desc1_size[0]）:
????????dotprods?=?dot（desc1[i:]desc2t）?#?vector