I want to find the sub-image from large image using PIL library. I also want to know the coordinates where it is found ?
Python – Display Image using PIL To show or display an image in Python Pillow, you can use show() method on an image object. The show() method writes the image to a temporary file and then triggers the default program to display that image. Once the program execution is completed, the temporary file will be deleted.
Python Imaging Library is a free and open-source additional library for the Python programming language that adds support for opening, manipulating, and saving many different image file formats. It is available for Windows, Mac OS X and Linux. The latest version of PIL is 1.1.
To load the image, we simply import the image module from the pillow and call the Image. open(), passing the image filename. Instead of calling the Pillow module, we will call the PIL module as to make it backward compatible with an older module called Python Imaging Library (PIL).
With PIL you can easily access and change the data stored in the pixels of an image. To get the pixel map, call load() on an image. The pixel data can then be retrieved by indexing the pixel map as an array.
import cv2
import numpy as np
image = cv2.imread("Large.png")
template = cv2.imread("small.png")
result = cv2.matchTemplate(image,template,cv2.TM_CCOEFF_NORMED)
print np.unravel_index(result.argmax(),result.shape)
This works fine and in efficient way for me.
I managed to do this only using PIL.
Some caveats:
Here's the code:
import os
from itertools import izip
from PIL import Image, ImageGrab
def iter_rows(pil_image):
"""Yield tuple of pixels for each row in the image.
From:
http://stackoverflow.com/a/1625023/1198943
:param PIL.Image.Image pil_image: Image to read from.
:return: Yields rows.
:rtype: tuple
"""
iterator = izip(*(iter(pil_image.getdata()),) * pil_image.width)
for row in iterator:
yield row
def find_subimage(large_image, subimg_path):
"""Find subimg coords in large_image. Strip transparency for simplicity.
:param PIL.Image.Image large_image: Screen shot to search through.
:param str subimg_path: Path to subimage file.
:return: X and Y coordinates of top-left corner of subimage.
:rtype: tuple
"""
# Load subimage into memory.
with Image.open(subimg_path) as rgba, rgba.convert(mode='RGB') as subimg:
si_pixels = list(subimg.getdata())
si_width = subimg.width
si_height = subimg.height
si_first_row = tuple(si_pixels[:si_width])
si_first_row_set = set(si_first_row) # To speed up the search.
si_first_pixel = si_first_row[0]
# Look for first row in large_image, then crop and compare pixel arrays.
for y_pos, row in enumerate(iter_rows(large_image)):
if si_first_row_set - set(row):
continue # Some pixels not found.
for x_pos in range(large_image.width - si_width + 1):
if row[x_pos] != si_first_pixel:
continue # Pixel does not match.
if row[x_pos:x_pos + si_width] != si_first_row:
continue # First row does not match.
box = x_pos, y_pos, x_pos + si_width, y_pos + si_height
with large_image.crop(box) as cropped:
if list(cropped.getdata()) == si_pixels:
# We found our match!
return x_pos, y_pos
def find(subimg_path):
"""Take a screenshot and find the subimage within it.
:param str subimg_path: Path to subimage file.
"""
assert os.path.isfile(subimg_path)
# Take screenshot.
with ImageGrab.grab() as rgba, rgba.convert(mode='RGB') as screenshot:
print find_subimage(screenshot, subimg_path)
Speed:
$ python -m timeit -n1 -s "from tests.screenshot import find" "find('subimg.png')"
(429, 361)
(465, 388)
(536, 426)
1 loops, best of 3: 316 msec per loop
While running the above command I moved the window containing the subimage diagonally as timeit
was running.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With