If the title isn't clear let's say I have a list of images (10k+), and I have a target image I am searching for.
Here's an example of the target image:
Here's an example of images I will want to be searching to find something 'similar' (ex1, ex2, and ex3):
Here's the matching I do (I use KAZE)
from matplotlib import pyplot as plt
import numpy as np
import cv2
from typing import List
import os
import imutils
def calculate_matches(des1: List[cv2.KeyPoint], des2: List[cv2.KeyPoint]):
"""
does a matching algorithm to match if keypoints 1 and 2 are similar
@param des1: a numpy array of floats that are the descriptors of the keypoints
@param des2: a numpy array of floats that are the descriptors of the keypoints
@return:
"""
# bf matcher with default params
bf = cv2.BFMatcher(cv2.NORM_L2)
matches = bf.knnMatch(des1, des2, k=2)
topResults = []
for m, n in matches:
if m.distance < 0.7 * n.distance:
topResults.append([m])
return topResults
def compare_images_kaze():
cwd = os.getcwd()
target = os.path.join(cwd, 'opencv_target', 'target.png')
images_list = os.listdir('opencv_images')
for image in images_list:
# get my 2 images
img2 = cv2.imread(target)
img1 = cv2.imread(os.path.join(cwd, 'opencv_images', image))
for i in range(0, 360, int(360 / 8)):
# rotate my image by i
img_target_rotation = imutils.rotate_bound(img2, i)
# Initiate KAZE object with default values
kaze = cv2.KAZE_create()
kp1, des1 = kaze.detectAndCompute(img1, None)
kp2, des2 = kaze.detectAndCompute(img2, None)
matches = calculate_matches(des1, des2)
try:
score = 100 * (len(matches) / min(len(kp1), len(kp2)))
except ZeroDivisionError:
score = 0
print(image, score)
img3 = cv2.drawMatchesKnn(img1, kp1, img_target_rotation, kp2, matches,
None, flags=2)
img3 = cv2.cvtColor(img3, cv2.COLOR_BGR2RGB)
plt.imshow(img3)
plt.show()
plt.clf()
if __name__ == '__main__':
compare_images_kaze()
Here's the result of my code:
ex1.png 21.052631578947366
ex2.png 0.0
ex3.png 42.10526315789473
It does alright, It was able to tell that ex1 is similar and ex2 is not similar. however it states that ex3 is similar (even more similar than ex1), Any extra pre-processing or post-processing (maybe ml? assuming ml is actually useful) or just changes I can do to my method that can be done to keep only ex1 as similar and not ex3?
(Note this score I create is something I found online. Not sure if it's an accurate way to go about it)
ADDED MORE EXAMPLES BELOW
Another set of examples:
Here's what I am searching for
I want the above image to be similar to the middle and bottom images (NOTE: I rotate my target image by 45 degrees and compare it to the images below.)
Feature matching (as stated in answers below) were useful in found similarity with the second image, but not the third image (Even after rotating it properly)
You can use template matching , where the image you want to detect if it's in the other images is the template. I have that small image saved in template.png
, and the other three images in img1.png
, img2.png
and img3.png
.
I defined a function that utilizes the cv2.matchTemplate
to calculate the amount of confidence for if a template is in an image. Using the function on every image, the one that results ion the highest confidence is the image that contains the template:
import cv2
template = cv2.imread("template.png", 0)
files = ["img1.png", "img2.png", "img3.png"]
for name in files:
img = cv2.imread(name, 0)
print(f"Confidence for {name}:")
print(cv2.matchTemplate(img, template, cv2.TM_CCOEFF_NORMED).max())
Confidence for img1.png:
0.8906427
Confidence for img2.png:
0.4427919
Confidence for img3.png:
0.5933967
cv2.imread
method to 0
:import cv2
template = cv2.imread("template.png", 0)
files = ["img1.png", "img2.png", "img3.png"]
for name in files:
img = cv2.imread(name, 0)
cv2.matchTemplate
to detect the template in each image. There are many detection methods you can use, but for this I decided to use the cv2.TM_CCOEFF_NORMED
method: print(f"Confidence for {name}:")
print(cv2.matchTemplate(img, template, cv2.TM_CCOEFF_NORMED).max())
The output of the function ranges from between 0
and 1
, and as you can see, it successfully detected that the first image is most likely to contain the template image (it has the highest level of confidence) .
If detecting which image contains the template isn't enough, and you want a visualization, you can try the code below:
import cv2
import numpy as np
def confidence(img, template):
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
template = cv2.cvtColor(template, cv2.COLOR_BGR2GRAY)
res = cv2.matchTemplate(img, template, cv2.TM_CCOEFF_NORMED)
conf = res.max()
return np.where(res == conf), conf
files = ["img1.png", "img2.png", "img3.png"]
template = cv2.imread("template.png")
h, w, _ = template.shape
for name in files:
img = cv2.imread(name)
([y], [x]), conf = confidence(img, template)
cv2.rectangle(img, (x, y), (x + w, y + h), (0, 0, 255), 2)
text = f'Confidence: {round(float(conf), 2)}'
cv2.putText(img, text, (x, y), 1, cv2.FONT_HERSHEY_PLAIN, (0, 0, 0), 2)
cv2.imshow(name, img)
cv2.imshow('Template', template)
cv2.waitKey(0)
import cv2
import numpy as np
cv2.matchTemplate
method requires grayscale images, convert the 2 images into grayscale:def confidence(img, template):
img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
template = cv2.cvtColor(template, cv2.COLOR_BGR2GRAY)
cv2.matchTemplate
method to detect the template in the image, and return the position of the point with the highest confidence, and return the highest confidence: res = cv2.matchTemplate(img, template, cv2.TM_CCOEFF_NORMED)
conf = res.max()
return np.where(res == conf), conf
files = ["img1.png", "img2.png", "img3.png"]
template = cv2.imread("template.png")
h, w, _ = template.shape
confidence
function we defined before, get the xy position of the top-left corner of the detected template and the confidence amount for the detection:for name in files:
img = cv2.imread(name)
([y], [x]), conf = confidence(img, template)
cv2.rectangle(img, (x, y), (x + w, y + h), (0, 0, 255), 2)
text = f'Confidence: {round(float(conf), 2)}'
cv2.putText(img, text, (x, y), 1, cv2.FONT_HERSHEY_PLAIN, (0, 0, 0), 2)
cv2.imshow(name, img)
cv2.imshow('Template', template)
cv2.waitKey(0)
I'm not sure, if the given images resemble your actual task or data, but for this kind of images, you could try simple template matching, cf. this OpenCV tutorial .
Basically, I just implemented the tutorial with some modifications:
import cv2
import matplotlib.pyplot as plt
# Read images
examples = [cv2.imread(img) for img in ['ex1.png', 'ex2.png', 'ex3.png']]
target = cv2.imread('target.png')
h, w = target.shape[:2]
# Iterate examples
for i, img in enumerate(examples):
# Template matching
# cf. https://docs.opencv.org/4.5.2/d4/dc6/tutorial_py_template_matching.html
res = cv2.matchTemplate(img, target, cv2.TM_CCOEFF_NORMED)
# Get location of maximum
_, max_val, _, top_left = cv2.minMaxLoc(res)
# Set up threshold for decision target found or not
thr = 0.7
if max_val > thr:
# Show found target in example
bottom_right = (top_left[0] + w, top_left[1] + h)
cv2.rectangle(img, top_left, bottom_right, (0, 255, 0), 2)
# Visualization
plt.figure(i, figsize=(10, 5))
plt.subplot(1, 2, 1), plt.imshow(img[..., [2, 1, 0]]), plt.title('Example')
plt.subplot(1, 2, 2), plt.imshow(res, vmin=0, vmax=1, cmap='gray')
plt.title('Matching result'), plt.colorbar(), plt.tight_layout()
plt.show()
These are the results:
----------------------------------------
System information
----------------------------------------
Platform: Windows-10-10.0.16299-SP0
Python: 3.9.1
PyCharm: 2021.1.1
Matplotlib: 3.4.1
OpenCV: 4.5.1
----------------------------------------
EDIT: To emphasize the information from the different colors, one might use the hue channel from the HSV color space for the template matching:
import cv2
import matplotlib.pyplot as plt
# Read images
examples = [
[cv2.imread(img) for img in ['ex1.png', 'ex2.png', 'ex3.png']],
[cv2.imread(img) for img in ['ex12.png', 'ex22.png', 'ex32.png']]
]
targets = [
cv2.imread('target.png'),
cv2.imread('target2.png')
]
# Iterate examples and targets
for i, (ex, target) in enumerate(zip(examples, targets)):
for j, img in enumerate(ex):
# Rotate last image from second data set
if (i == 1) and (j == 2):
img = cv2.rotate(img, cv2.ROTATE_90_CLOCKWISE)
h, w = target.shape[:2]
# Get hue channel from HSV color space
target_h = cv2.cvtColor(target, cv2.COLOR_BGR2HSV)[..., 0]
img_h = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)[..., 0]
# Template matching
# cf. https://docs.opencv.org/4.5.2/d4/dc6/tutorial_py_template_matching.html
res = cv2.matchTemplate(img_h, target_h, cv2.TM_CCOEFF_NORMED)
# Get location of maximum
_, max_val, _, top_left = cv2.minMaxLoc(res)
# Set up threshold for decision target found or not
thr = 0.6
if max_val > thr:
# Show found target in example
bottom_right = (top_left[0] + w, top_left[1] + h)
cv2.rectangle(img, top_left, bottom_right, (0, 255, 0), 2)
# Visualization
plt.figure(i * 10 + j, figsize=(10, 5))
plt.subplot(1, 2, 1), plt.imshow(img[..., [2, 1, 0]]), plt.title('Example')
plt.subplot(1, 2, 2), plt.imshow(res, vmin=0, vmax=1, cmap='gray')
plt.title('Matching result'), plt.colorbar(), plt.tight_layout()
plt.savefig('{}.png'.format(i * 10 + j))
plt.show()
New results:
We can use the cv2.matchTemplate
method to detect where an image is in another image, but for your second set of images you have rotation. Also, we'll need to take the colors into account.
cv2.matchTemplate
will take in an image, a template (the other image) and a template detection method, and will return a grayscale array where the brightest point in the grayscale array will be the point with the most confidence that template is at that point.
We can use the template at 4 different angles and use the one that resulted in the highest confidence. When we detected a possible point that matched the template, we use a function (that we will define ourselves) to check if the most frequent colors in the template is present in the patch of the image we detected. If not, then ignore the patch, regardless of the amount of confidence returned.
import cv2
import numpy as np
def frequent_colors(img, vals=3):
colors, count = np.unique(np.vstack(img), return_counts=True, axis=0)
sorted_by_freq = colors[np.argsort(count)]
return sorted_by_freq[-vals:]
def get_templates(img):
template = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
for i in range(3):
yield cv2.rotate(template, i)
def detect(img, template, min_conf=0.45):
colors = frequent_colors(template)
img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
conf_max = min_conf
shape = 0, 0, 0, 0
for tmp in get_templates(template):
h, w = tmp.shape
res = cv2.matchTemplate(img_gray, tmp, cv2.TM_CCOEFF_NORMED)
for y, x in zip(*np.where(res > conf_max)):
conf = res[y, x]
if conf > conf_max:
seg = img[y:y + h, x:x + w]
if all(np.any(np.all(seg == color, -1)) for color in colors):
conf_max = conf
shape = x, y, w, h
return shape
files = ["img1_2.png", "img2_2.png", "img3_2.png"]
template = cv2.imread("template2.png")
for name in files:
img = cv2.imread(name)
x, y, w, h = detect(img, template)
cv2.rectangle(img, (x, y), (x + w, y + h), (0, 0, 255), 2)
cv2.imshow(name, img)
cv2.imshow('Template', template)
cv2.waitKey(0)
import cv2
import numpy as np
frequent_colors
, that will take in an image and return the most frequent colors in the image. An optional parameter, val
, is how many colors to return; if val
is 3
, then the 3 most frequent colors will be returned:def frequent_colors(img, vals=3):
colors, count = np.unique(np.vstack(img), return_counts=True, axis=0)
sorted_by_freq = colors[np.argsort(count)]
return sorted_by_freq[-vals:]
get_templates
, that will take in an image, and yield the image (in grayscale) at 4 different angles - original, 90 clockwise, 180, and 90 counterclockwise:def get_templates(img):
template = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
for i in range(3):
yield cv2.rotate(template, i)
detect
, that will take in an image and a template image, and return the x, y, w, h of the bounding box of the detected template on the image, and for this function we will be utilizing the frequent_colors
and get_templates
functions defined earlier. The min_conf
parameter will be the minimum amount of confidence needed to classify a detection as an actual detection: def detect(img, template, min_conf=0.45):
colors
. Also, define a grayscale version of the main image: colors = frequent_colors(template)
img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
conf_max = min_conf
shape = 0, 0, 0, 0
cv2.matchTemplate
method to get the grayscale array of detected templates on the image: for tmp in get_templates(template):
h, w = tmp.shape
res = cv2.matchTemplate(img_gray, tmp, cv2.TM_CCOEFF_NORMED)
conf_min
, and store the confidence in a variable, conf
. If conf
is greater than the initial greatest confidence variable ( conf_max
) , proceed to detect if all three most frequent colors in the template is present in the patch of the image: for y, x in zip(*np.where(res > conf_max)):
conf = res[y, x]
if conf > conf_max:
seg = img[y:y + h, x:x + w]
if all(np.any(np.all(seg == color, -1)) for color in colors):
conf_max = conf
shape = x, y, w, h
0, 0, 0, 0
: return shape
detect
function we defined to get the x, y, w, h of the bounding box. Use the cv2.rectangle
method to draw the bounding box onto the images:files = ["img1_2.png", "img2_2.png", "img3_2.png"]
template = cv2.imread("template2.png")
for name in files:
img = cv2.imread(name)
x, y, w, h = detect(img, template)
cv2.rectangle(img, (x, y), (x + w, y + h), (0, 0, 255), 2)
cv2.imshow(name, img)
cv2.imshow('Template', template)
cv2.waitKey(0)
First, the data appears in graphs, aren't you able to get the overlapping values from their numerical data?
And have you tried performing some edge detection for the change in color from white-blue and then from blue-red, fitting some circles to those edges and then checking if they overlap?
Since the input data is quite controlled (no organic photography or videos), perhaps you won't have to go the ML route.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.