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计算机视觉 - 1.数元素数目

计算机视觉1 - 数元素数目

0. 任务目标

  1. 统计每幅图中各化学元素的数目;
  2. 统计AI和Fe元素、Fe和P元素、AI和P元素重叠的数目,并且以图像的形式展示出两两元素的重叠情况;
  3. 统计AI、Fe和P元素三者重叠的数目,并以图像的形式展示出三种元素重叠情况。
  4. 无论原始图像中的化学元素是何种颜色,均可实现本目标。

1. 实现任务

计算机视觉常用的方法是使用OpenCV的库函数对图像进行处理。因此我们先利用 cv2.imread() 函数读入图像数据。本例子中,共拥有3张图片,分别是Al,Fe和P(即铝、铁、磷)三种化学元素。下面是三张照片的样子。

Al

Fe

P

读取的代码如下:

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# Set paths
al_path = os.path.join('image', 'Al.jpg')
fe_path = os.path.join('image', 'Fe.jpg')
p_path = os.path.join('image', 'P.jpg')

# Read images
al = cv2.imread(al_path)
fe = cv2.imread(fe_path)
p = cv2.imread(p_path)

注意,这里的路径最好不要直接写死,而是用python os库中提供的 os.path.join() 函数进行拼接处理。该函数能够自行判断当前运行环境而选择路径的分隔符,无论是Linux还是Windows都不会出错。


读入图片后,我们发现图片中的左上角logo处和左下角的 50nm 标识都不是我们需要的东西,需要剔除。因此我们需要对输入图像进行预处理:

  • 为了去除左上角的logo,根据观察可以看到,logo读取进来的图像矩阵所在的行数均在74行及以内,因此我们处理的时候可以针对logo所在的行数进行删除。

  • 为了去除左下角的 50nm 标识,我们需要识别出白色区域并去除。

为了实现上面的目标,我们先将图片从RGB色彩通道转换为HSV(HSB)色彩通道。OpenCV的库函数也提供了相应的转换。我们平常所见的图片绝大多数都是RGB通道,即利用Red(红)、Green(绿)、Blue(蓝)三种颜色及其浓度来表示一张彩色图片。在8Bit色深的RGB图像中,RGB三个通道的取值区间均为[0, 255]。而HSV色彩通道是利用Hue(色调)、Saturation(饱和度)、Value(明度)三值来表示颜色。不同于RGB图像,HSV图像是根据色调H来确定颜色的,而RGB图像一般需要通过三个值共同参与来表达一种颜色。

处理代码如下:

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# RGB TO HSV
def rgb2hsv(img):
    hsv_img = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    # split H, S, V
    h, s, v = cv2.split(hsv_img)
    return [h, s, v]

显示HSV图像三通道的代码如下:

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def show_hsv_image(imgs: list):
    cv2.imshow('H', imgs[0])
    cv2.imshow('S', imgs[1])
    cv2.imshow('V', imgs[2])
    cv2.waitKey(0)
    cv2.destroyAllWindows()

未经处理前,Al的分拆HSV通道后的图像如下:

Al的HSV图像

在HSV图像中,查询可知黑色点范围如下:

  • H: [0, 180]
  • S: [0, 255]
  • V: [0, 46]

白色点范围如下:

  • H: [0, 180]
  • S: [0, 30]
  • V: [221, 255]

logo区域的像素点较为明亮,因此可以直接利用位置和V的值进行判断去除。

图像预处理代码如下:

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def remove_light(split_img: list):
    h, s, v = split_img
    for i in range(h.shape[0]):
        for j in range(h.shape[1]):
            # Remove black points
            if 0 <= h[i, j] <= 180 and 0 <= v[i, j] <= 46:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0
            # Remove white points
            elif 0 <= h[i, j] <= 180 and 221 <= v[i, j] <= 255 and 0 <= s[i, j] <= 30:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0
            # Remove logo area
            if i <= 70 and 180 <= v[i, j] <= 255:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0

    return [h, s, v]

统计元素量时,为了方便统计,我们把有颜色的像素点都统计为1个元素。而我们已在上一步去除了杂色点,因此这一步可以直接数图像V通道的点数进行统计。统计函数如下:

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# Counting
def count_points(img: list):
    h, s, v = img
    counter = 0
    for i in range(v.shape[0]):
        for j in range(v.shape[1]):
            if v[i, j] != 0:
                counter += 1

    return counter

统计重叠量时,依旧是利用上一步的思想进行统计,但是这时候我们需要两张图片的交集,即需要多加一个“与”的判断步骤。为了显示图片,我们还需要返回合并后的HSV矩阵。

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def count2overlap(img1: list, img2: list):
    h1, s1, v1 = img1
    h2, s2, v2 = img2
    h0 = np.zeros(h1.shape, dtype=np.uint8)
    s0 = np.zeros(s1.shape, dtype=np.uint8)
    v0 = np.zeros(v1.shape, dtype=np.uint8)
    counter = 0
    for i in range(v1.shape[0]):
        for j in range(v1.shape[1]):
            if v1[i, j] != 0 and v2[i, j] != 0:
                h0[i, j] = h1[i, j] + h2[i, j]
                s0[i, j] = s1[i, j] + s2[i, j]
                v0[i, j] = v1[i, j] + v2[i, j]
                counter += 1

    return counter, [h0, s0, v0]

三张图片的元素重叠量也是同理。

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def count3overlap(img1: list, img2: list, img3: list):
    h1, s1, v1 = img1
    h2, s2, v2 = img2
    h3, s3, v3 = img3
    h0 = np.zeros(h1.shape, dtype=np.uint8)
    s0 = np.zeros(s1.shape, dtype=np.uint8)
    v0 = np.zeros(v1.shape, dtype=np.uint8)
    counter = 0
    for i in range(v1.shape[0]):
        for j in range(v1.shape[1]):
            if v1[i, j] != 0 and v2[i, j] != 0 and v3[i, j] != 0:
                h0[i, j] = h1[i, j] + h2[i, j] + h3[i, j]
                s0[i, j] = s1[i, j] + s2[i, j] + s3[i, j]
                v0[i, j] = v1[i, j] + v2[i, j] + v3[i, j]
                counter += 1

    return counter, [h0, s0, v0]

至此,我们本例子的目标基本完成。由于我们将重要的功能封装成函数且与具体颜色无关,因此无论原始图像中的化学元素是何种颜色,只需修改图像路径,均可实现本目标。


完整代码如下:

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import os.path
import cv2
import numpy as np
import matplotlib.pyplot as plt

# Set paths
al_path = os.path.join('image', 'Al.jpg')
fe_path = os.path.join('image', 'Fe.jpg')
p_path = os.path.join('image', 'P.jpg')

# Read images
al = cv2.imread(al_path)
fe = cv2.imread(fe_path)
p = cv2.imread(p_path)


# RGB TO HSV
def rgb2hsv(img):
    hsv_img = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    # split H, S, V
    h, s, v = cv2.split(hsv_img)
    return [h, s, v]


# Plot image
def show_image3(imgs: list):
    plt.figure(figsize=(15, 15))
    for i, img in enumerate(imgs):
        plt.subplot(1, 3, i + 1)
        plt.imshow(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
        plt.axis('off')
    plt.show()


# Plot HSV image
def show_hsv_image(imgs: list):
    cv2.imshow('H', imgs[0])
    cv2.imshow('S', imgs[1])
    cv2.imshow('V', imgs[2])
    cv2.waitKey(0)
    cv2.destroyAllWindows()


# Remove black and white points and logo
def remove_light(split_img: list):
    h, s, v = split_img
    for i in range(h.shape[0]):
        for j in range(h.shape[1]):
            # Remove black points
            if 0 <= h[i, j] <= 180 and 0 <= v[i, j] <= 46:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0
            # Remove white points
            elif 0 <= h[i, j] <= 180 and 221 <= v[i, j] <= 255 and 0 <= s[i, j] <= 30:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0
            # Remove logo area
            if i <= 70 and 180 <= v[i, j] <= 255:
                h[i, j] = 0
                s[i, j] = 0
                v[i, j] = 0

    return [h, s, v]


# Counting
def count_points(img: list):
    h, s, v = img
    counter = 0
    for i in range(v.shape[0]):
        for j in range(v.shape[1]):
            if v[i, j] != 0:
                counter += 1

    return counter


images = [al, fe, p]
# show_image3(images)

hsv_al = rgb2hsv(al)
hsv_fe = rgb2hsv(fe)
hsv_p = rgb2hsv(p)
show_hsv_image(hsv_al)

# pre-process
processed_al = remove_light(hsv_al)
processed_fe = remove_light(hsv_fe)
processed_p = remove_light(hsv_p)

# counting
counter_al = count_points(processed_al)
counter_fe = count_points(processed_fe)
counter_p = count_points(processed_p)

print("Al元素的点数:", counter_al)
print("Fe元素的点数:", counter_fe)
print("P元素的点数:", counter_p)


# 求解重叠量,并将两者的重叠量画出来
def count2overlap(img1: list, img2: list):
    h1, s1, v1 = img1
    h2, s2, v2 = img2
    h0 = np.zeros(h1.shape, dtype=np.uint8)
    s0 = np.zeros(s1.shape, dtype=np.uint8)
    v0 = np.zeros(v1.shape, dtype=np.uint8)
    counter = 0
    for i in range(v1.shape[0]):
        for j in range(v1.shape[1]):
            if v1[i, j] != 0 and v2[i, j] != 0:
                h0[i, j] = h1[i, j] + h2[i, j]
                s0[i, j] = s1[i, j] + s2[i, j]
                v0[i, j] = v1[i, j] + v2[i, j]
                counter += 1

    return counter, [h0, s0, v0]


# 求解三者的重叠量
def count3overlap(img1: list, img2: list, img3: list):
    h1, s1, v1 = img1
    h2, s2, v2 = img2
    h3, s3, v3 = img3
    h0 = np.zeros(h1.shape, dtype=np.uint8)
    s0 = np.zeros(s1.shape, dtype=np.uint8)
    v0 = np.zeros(v1.shape, dtype=np.uint8)
    counter = 0
    for i in range(v1.shape[0]):
        for j in range(v1.shape[1]):
            if v1[i, j] != 0 and v2[i, j] != 0 and v3[i, j] != 0:
                h0[i, j] = h1[i, j] + h2[i, j] + h3[i, j]
                s0[i, j] = s1[i, j] + s2[i, j] + s3[i, j]
                v0[i, j] = v1[i, j] + v2[i, j] + v3[i, j]
                counter += 1

    return counter, [h0, s0, v0]


# Get 2 overlap
overlap_al_fe, overlap_img_af = count2overlap(processed_al, processed_fe)
overlap_al_p, overlap_img_ap = count2overlap(processed_al, processed_p)
overlap_fe_p, overlap_img_fp = count2overlap(processed_fe, processed_p)
overlap_img_af = cv2.cvtColor(cv2.merge(overlap_img_af), cv2.COLOR_HSV2BGR)
overlap_img_ap = cv2.cvtColor(cv2.merge(overlap_img_ap), cv2.COLOR_HSV2BGR)
overlap_img_fp = cv2.cvtColor(cv2.merge(overlap_img_fp), cv2.COLOR_HSV2BGR)
print("Al和Fe的重叠量:", overlap_al_fe)
print("Al和P的重叠量:", overlap_al_p)
print("Fe和P的重叠量:", overlap_fe_p)
# show_image3([overlap_img_af, overlap_img_ap, overlap_img_fp])

# Get 3 overlap
overlap_all, overlap_img_all = count3overlap(processed_al, processed_fe, processed_p)
overlap_img_all = cv2.cvtColor(cv2.merge(overlap_img_all), cv2.COLOR_HSV2BGR)
print("Al, Fe和P的重叠量:", overlap_all)
# cv2.imshow('Overlay with Al, Fe and P elements', overlap_img_all)
# cv2.waitKey(0)
# cv2.destroyAllWindows()

# Save images
if not os.path.exists('image_out'):
    os.makedirs('image_out')
cv2.imwrite(os.path.join('image_out', 'overlap_img_af.jpg'), overlap_img_af)
cv2.imwrite(os.path.join('image_out', 'overlap_img_ap.jpg'), overlap_img_ap)
cv2.imwrite(os.path.join('image_out', 'overlap_img_fp.jpg'), overlap_img_fp)
cv2.imwrite(os.path.join('image_out', 'overlap_img_all.jpg'), overlap_img_all)

最终的得到的重叠图片如下:

  • Al和Fe:

    overlap_img_af

  • Al和P:

    overlap_img_ap

  • Fe和P:

    overlap_img_fp

  • 三者重叠:

    overlap_img_all

本文由作者按照 CC BY 4.0 进行授权