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counting pixels in an image(ocr)

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kiddo39

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counting pixels in an image(ocr)

Dec 3rd, 2008

I have a small image with a black background and red lines in it and I need to count the red pixels. I know I need PIL, but I'm not sure which method to use. Then once I have the counts I need to equate them to a character, so if the red lines in the image form a circle and have x amount of red pixels, its = '0', and if the image forms a straight line and is found to have x amount of pixels it's = 'l'.

 Help with Code Tags 
 Python Syntax (Toggle Plain Text) 
import Image
#mypic.jpg is the circle
im=image.open("mypic.jpg")
im.getcolors(R)
# if statement here
import Image
#mypic.jpg is the circle
im=image.open("mypic.jpg")
im.getcolors(R)
# if statement here

Any suggestions?

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Paul Thompson Paul Thompson is offline

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Re: counting pixels in an image(ocr)

Dec 4th, 2008

Could you test how many pixels are red? Because a circle will require many more pixels to draw then a line.
I know when getting colours i used something like:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
import Image
im = image.open("myPic.jpg")
for pixel in im.getdata():
    #check if it is red
import Image
im = image.open("myPic.jpg")
for pixel in im.getdata():
    #check if it is red

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vegaseat

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Re: counting pixels in an image(ocr)

Dec 4th, 2008

Played around with it a little ...

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
# use PIL to count pixels in letters I and O
# image file needs to be a bitmap file to maintain
# red (255,0,0) and black (0,0,0) pixel colors correctly
 
from PIL import Image
 
# img_I.bmp --> 50x50 black bg + red I (times new roman, bold, 24)
img_I = Image.open("img_I.bmp").getdata()
 
# img_O.bmp --> 50x50 black bg + red O (times new roman, bold, 24)
img_O = Image.open("img_O.bmp").getdata()
 
# count red pixels of the I
# list(img_I) is a list of (r,g,b) color tuples for each pixel
# where (255,0,0) would be the red pixel
red_I = 0
for red in list(img_I):
    if red == (255,0,0):
        red_I += 1
 
print red_I  # 76
 
# count red pixels of the O
red_O = 0
for red in list(img_O):
    if red == (255,0,0):
        red_O += 1
 
print red_O  # 126
# use PIL to count pixels in letters I and O
# image file needs to be a bitmap file to maintain
# red (255,0,0) and black (0,0,0) pixel colors correctly

from PIL import Image

# img_I.bmp --> 50x50 black bg + red I (times new roman, bold, 24)
img_I = Image.open("img_I.bmp").getdata()

# img_O.bmp --> 50x50 black bg + red O (times new roman, bold, 24)
img_O = Image.open("img_O.bmp").getdata()

# count red pixels of the I
# list(img_I) is a list of (r,g,b) color tuples for each pixel
# where (255,0,0) would be the red pixel
red_I = 0
for red in list(img_I):
    if red == (255,0,0):
        red_I += 1

print red_I  # 76

# count red pixels of the O
red_O = 0
for red in list(img_O):
    if red == (255,0,0):
        red_O += 1

print red_O  # 126