使用openCV查找图像中的特定框
我有以下图像：
框，其中显示一个三角形。我使用简单的垂直和水平线检测来完成此操作，这在我的机器上总共花费了10秒钟。
现在，由于必须执行很多次，因此效率非常令人关注。那么，openCV（或其他任何地方）中是否有任何方法可以有效地提取这些框？在这里，一种有效的方法比蛮力方法所需的时间短。
感谢您的帮助！
我的方法：
我制作了一个函数searchHorizontalLinesX，该函数用于搜索特定长度的行。它通过遍历每个像素一次。我的图像尺寸为：2479 x 3504 = 8686416像素。 （由于上传限制为2MB，附件中的图像质量很低。我正在使用的图像超过16 MB）
因此，我输入了整个盒子的宽度（L1），并输入了编号为5（L2）的盒子的宽度。现在，该函数返回具有L1长度和L2长度的行。因此，所有具有L1长度的对象都可以用于提取框1,2,3,4,6,7,8,9和10。
找到线后，我将搜索它们之间具有H差的线，其中H是每个框的高度。使用这些我得到箱子。
对于不是提取出来的整个列的框，我尝试找到一条从上到下的线，然后在该行的相关侧提取图像。
def searchHorizontalLinesX(im,lengths,pg,gap=10):
"""
im: PIL image object of the file
lengths: list of lengths of lines to recognize
pg: Page number of the page to take under consideration
"""
im.seek(pg)
dimX = im.size[0]
dimY = im.size[1]
pix = im.load()
line = False
n = len(lengths)
linez = [[] for i in range(0,n)]
for j in range(0,dimY):
for i in range(0,dimX):
if(line):
if(pix[i,j][0]!=0 or pix[i,j][1]!=255):
line = False
end = (i-1,j)
for num,l in enumerate(lengths):
if(end[0]-start[0]>(l-gap) and end[0]-start[0]<(l+gap)):
linez[num].append([start,end])
elif(start[1]==j-1 and i==0):#End to end line
end = (im.size[0],start[1])
line = False
for i,l in enumerate(lengths):
if(end[0]-start[0]>(l-gap) and end[0]-start[0]<(l+gap)):
linez[num].append([start,end])
else:
if(pix[i,j][0]==0 or pix[i,j][1]==255):
start = (i,j)
line = True
return linez
def searchVerticalLines(im,length,pg,gap=5):
"""
im: PIL image object of the file
length: Length of box
dimX: Width of the page
dimY: Height of the page
pg: Page number of the page to take under consideration
"""
im.seek(pg)
dimX = im.size[0]
dimY = im.size[1]
pix = im.load()
line = False
linez = []
start = (0,0)
end = (0,0)
for i in range(0,dimX):
for j in range(0,dimY):
if(line):
if(pix[i,j][0]!=0 or pix[i,j][1]!=255):
line = False
end = (i,j-1)
if(end[1]-start[1]>(length-gap) and end[1]-start[1]<(length+gap)):
linez.append([start,end])
elif(start[0]==i-1 and j==0):
line = False
end = (start[0],im.size[1])
if(end[1]-start[1]>(length-gap) and end[1]-start[1]<(length+gap)):
linez.append([start,end])
else:
if(pix[i,j][0]==0 or pix[i,j][1]==255):
start = (i,j)
line = True
return linez
def grouping(hor,width):
"""
Groups similar horizontal lines together.
hor: List of lines in the format [[(start_x,start_y),(end_x,end_y)],...]
width: What width can a line have. Takes all the lines inside this list into a group
Returns: A list of groups. Each group is a list of lines. Each line has the format [(start_x,start_y),(end_x,end_y)]
"""
horSet = set()
for i in hor:
horSet.add((i[0],i[1]))
group = []
count = 0
for i in hor:
if (i[0],i[1]) in horSet:
print("Visiting :"+str(i))
for j in hor:
if (j[0],j[1]) in horSet:
if(i[0][0]==j[0][0] and i[1][0]==j[1][0] and abs(j[0][1]-i[0][1])<width and abs(j[1][1]-i[1][1])<width):
if(len(group)<=count):
group.append([j])
else:
group[count].append(j)
horSet.remove((j[0],j[1]))
count+=1
return group
def groupingH(ver,width,heightDifference = 2):
"""
Groups similar vertical lines together.
hor: List of lines in the format [[(start_x,start_y),(end_x,end_y)],...]
width: What width can a line have. Takes all the lines inside this list into a group
Returns: A list of groups. Each group is a list of lines. Each line has the format [(start_x,start_y),(end_x,end_y)]
"""
verSet = set()
for i in ver:
verSet.add((i[0],i[1]))
group = []
count = 0
for i in ver:
if (i[0],i[1]) in verSet:
for j in ver:
if (abs(i[0][1]-j[0][1])< heightDifference and abs(i[1][1]-j[1][1])< heightDifference and abs(j[0][0]-i[0][0])<width and abs(j[1][0]-i[1][0])<width):
if(len(group)<=count):
group.append([j])
else:
group[count].append(j)
verSet.remove((j[0],j[1]))
count+=1
return group
def boxing(groupList,boxHeight,gap=5,lw=4):
"""
Given a groupList, it makes a list of coordinates of boxes that have a boxHeight height+-5
"""
boxCoord = []
groupSet = set()
for i in range(len(groupList)):
groupSet.add(i)
for i,g in enumerate(groupList):
if i in groupSet:
print("On :"+str(i))
for j,g1 in enumerate(groupList):
if j in groupSet:
print(" Checking :"+str(j))
if(g[0][0][0]==g1[0][0][0] and g[0][1][0]==g1[0][1][0] and abs(g[len(g)-1][0][1]-g1[0][0][1])>=boxHeight-gap and abs(g[len(g)-1][0][1]-g1[0][0][1])<boxHeight+gap):
groupSet.remove(j)
print(" removing :"+str(j))
boxCoord.append((g[0][0][0]+lw,min(g[len(g)-1][0][1],g1[0][0][1])+1,g[0][1][0]-lw,max(g[len(g)-1][0][1],g1[0][0][1])-1))
break
groupSet.remove(i)
return boxCoord
##############################
def getFrontPageBoxes(im,pg,coords,margin=10):
"""
coords[0]: List of lengths of horizontal lines to be recognized: 0th for box1, 1st for box2+3 (and 4,5,6,7,8,9,10)
coords[1]: Height of box 1
coords[2]: Height of box 2,3
coords[3]: Height of box 4,5,6,7
coords[4]: Height of box 8,10
coords[5]: Height of box 9
"""
# Box 1: Police station... et cetera.
t = []
t1 = t.append(time())
linez = searchHorizontalLinesX(im,coords[0],0) #0 for box 1 <-- Takes time
t2 = t.append(time())
groupForBox1 = grouping(linez[0],4)
leftUpperCorner = groupForBox1[0][len(groupForBox1[0])-1][0]
t3 = t.append(time())
verLinez = searchVerticalLines(im,coords[1],0,10) # <-- Takes time
t4 = t.append(time())
rightLowerCorner = verLinez[0][1]
box1 = im.crop((leftUpperCorner[0]+margin,leftUpperCorner[1]+margin,linez[0][0][1][0]-margin,rightLowerCorner[1]-margin))
# Box 2+3: Polling station name and address
groupForBox2 = grouping(linez[1],4)
bxesFor2 = boxing(groupForBox2,coords[2])
box2Uncropped = im.crop(bxesFor2[len(bxesFor2)-1]) # The last one is the one we want
t5 = t.append(time())
verLinesFor2 = searchVerticalLines(box2Uncropped,box2Uncropped.size[1],0,10) # <-- Takes time
t6 = t.append(time())
group2ForBox2 = groupingH(verLinesFor2,4)
leftUpperCorner = (0,0)
rightLowerCorner = group2ForBox2[0][0][1]
box2 = box2Uncropped.crop((leftUpperCorner[0]+margin,leftUpperCorner[1]+margin,rightLowerCorner[0]-margin,rightLowerCorner[1]-margin))
# Box 4,5,6,7:
groupForBox4 = groupForBox2
bxesFor4 = boxing(groupForBox4,coords[3])
box4Uncropped = im.crop(bxesFor4[0])
t7 = t.append(time())
verLinesFor4 = searchVerticalLines(box4Uncropped,box4Uncropped.size[1],0,10) # <-- Takes time
t8 = t.append(time())
group2ForBox4 = groupingH(verLinesFor4,4)
#There must be 5 groups.
# Error raising mechanism needed here
maleBox = box4Uncropped.crop((group2ForBox4[1][len(group2ForBox4[1])-1][0][0]+margin,0+margin,group2ForBox4[2][0][0][0]-margin,box4Uncropped.size[1]-margin))
femaleBox = box4Uncropped.crop((group2ForBox4[2][len(group2ForBox4[2])-1][0][0]+margin,0+margin,group2ForBox4[3][0][0][0]-margin,box4Uncropped.size[1]-margin))
third_gender = box4Uncropped.crop((group2ForBox4[3][len(group2ForBox4[3])-1][0][0]+margin,0+margin,group2ForBox4[4][0][0][0]-margin,box4Uncropped.size[1]-margin))
total = box4Uncropped.crop((group2ForBox4[4][len(group2ForBox4[4])-1][0][0]+margin,0+margin,box4Uncropped.size[0]-margin,box4Uncropped.size[1]-margin))
# Box 8, 10:
groupForBox8 = groupForBox2
bxesFor8 = boxing(groupForBox8,coords[4])
box8Uncropped = im.crop(bxesFor8[0])
t9 = t.append(time())
verLinesFor8 = searchVerticalLines(box8Uncropped,box8Uncropped.size[1],0,10) # <--Takes time
t10 = t.append(time())
group2ForBox8 = groupingH(verLinesFor8,4)
box10 = box8Uncropped.crop((group2ForBox8[0][len(group2ForBox8)-1][0][0]+margin,0+margin,box8Uncropped.size[0]-margin,box8Uncropped.size[1]-margin))
box8 = box8Uncropped.crop((0+margin,0+margin,group2ForBox8[0][0][0][0]-margin,box8Uncropped.size[1]-margin))
# Box 9:
groupForBox9 = groupForBox2
bxesFor9= boxing(groupForBox9,coords[5])
box9 = im.crop((bxesFor9[0][0]+margin,bxesFor9[0][1]+margin,bxesFor9[0][2]-margin,bxesFor9[0][3]-margin))
for i in range(0,len(t)-1):
print('Time taken :'+str(t[i+1]-t[i]))
return [box1,box2,maleBox,femaleBox,third_gender,total,box8,box9,box10]
def processBoxes(bxLst):
opList = []
for i,box in enumerate(bxLst):
print("box :"+str(i))
opList.append(pt.image_to_string(box,lang='hin+eng',config='--psm 6'))
return opList
def getFrontPageInfo(im,pg,coords):
"""
coords[0]: List of lengths of horizontal lines to be recognized: 0th for box1, 1st for box2+3,
2nd for boxes 4,5,6,7, 3rd for boxes 8 and 10, 4th for box 9
coords[1]: List of lengths of vertical lines to be recognized: 0th for box1
coords[2]: Height of box 2,3
coords[3]: Height of box 4,5,6,7
coords[4]: Height of box 8,10
coords[5]: Height of box 9
"""
boxList = getFrontPageBoxes(im,pg,coords)
return processBoxes(boxList)
1 个答案:
答案 0 :(得分：1)
查看我的代码以获取更多详细信息。我只制作了一个盒子的样本。将相同的方法应用于其他人。
import cv2
img = cv2.imread("1.png")
imgray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(imgray,127,255,0)
cv2.bitwise_not(thresh,thresh)
im2, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
#find the document in the image
max_area = 0
max_contour = None
ind = 0
for i,c in enumerate(contours):
area = cv2.contourArea(c)
if area>max_area:
max_area = area
max_contour = c
ind = i
cv2.drawContours(img, contours, ind ,(0,0,255), 2)
#extract the document
rect = cv2.boundingRect(max_contour)
roi = img[rect[1]:rect[1]+rect[3],rect[0]:rect[0]+rect[2]]
(h,w) = roi.shape[:2]
#create a mask (the mask of box 1)
mask1 = (0,0,w*0.88,h*0.062) #the parameter 0.88 and 0.062 were found base on the format of the document
cv2.rectangle(roi,(mask1[0],mask1[1]),(int(mask1[2]),int(mask1[3])),(0,255,0),2)
cv2.imshow("img",img)
cv2.imshow("ROI",roi)
cv2.waitKey()
cv2.destroyAllWindows()
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