Basic Image Processing operations using OpenCV and Python

opencv_basic.py

import cv2
import argparse

# Download the image used for this tutorial from here.
# http://goo.gl/jsYXl8

# Read the image
ap = argparse.ArgumentParser();
ap.add_argument("-i", "--image", required = True, help = "path to the image file");
args = vars(ap.parse_args());

# Read the image
image = cv2.imread(args["image"]);

# Convert the image into grayscale
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY);

# Get the size of the image
# Output is in the form of tuple 
# (height of image , width of image, no of channels)
print image.shape; # OUPTUT = (476, 640, 3)

# Accessing single pixel value
# image[y co-ordinate, x co-ordinate]
# Output is in the form of [B,G,R]
print image[379, 383]; # OUPTUT = [207 151 143]

# To get value of only one channel, use
# image[y co-ordinate, x co-ordinate, channel index]
# Channel are indexed as -
# 0 for Blue, 1 for Green and 2 for Red
# In the example below we print the Blue Channel Value
print image[379, 383, 1]; # OUPTUT = 151

# Clone the image
image_copy = image.copy();

# Display the image
cv2.imshow("Image", image);
cv2.waitKey(); # The program will wait till eternity, 

how to run this code. it shows parsing error on the path directory just like -i/--image

Hey! Same problem here! Can you please show us the way to solve this error: the following arguments are required: -i/--image. Thanks

Example of usage:
python3.5 opencv_basic.py -i fileName.png

Thank you isabelatelles!

hello isabelatelles
i am not able to understand wat u r trying to do
pls explain

In command line type:

python opencv_basic.py --image pathNameToThe image

make sure pathNameToThe image is like C:\Users\Saurav\Desktop\image.jpg
and put opencv_basic.py in the pwd

Hi, thanks for your code! I still have issues on how to used this code. (I am very new to python by the way and am using Python 3.7). Thank for your time.

Olá

como executar este código. mostra erro de análise no diretório do caminho, assim como -i / - imagem

Olá, execute o seguinte trecho no seu prompt: python opencv_basic.py --i nomedoseuarquivodeimagem.png setado para o local do arquivo de origem do projeto no seu disco local.

Oi, obrigado pelo seu código! Ainda tenho problemas em como usar esse código. (Eu sou muito novo para python e estou usando o Python 3.7). Obrigado pelo seu tempo.

Olá, execute o seguinte trecho no seu prompt: python opencv_basic.py --i nomedoseuarquivodeimagem.png setado para o local do arquivo de origem do projeto no seu disco local.

-- coding: utf-8 --

"""
Created on Wed Jun 10 16:30:20 2020

@author: siddh
"""

import cv2
import argparse
import numpy as np

ap = argparse.ArgumentParser()
ap.add_argument('-i', '--image', required=True,
help = 'path to input image')
ap.add_argument('-c', '--config', required=True,
help = 'path to yolo config file')
ap.add_argument('-w', '--weights', required=True,
help = 'path to yolo pre-trained weights')
ap.add_argument('-cl', '--classes', required=True,
help = 'path to text file containing class names')
args = ap.parse_args()

def get_output(model):
layer_names = model.getLayerNames()
output_layers = [layer_names[i[0]-1]for i in model.getUnconnectedOutLayers()]
return output_layers

def draw_preds(img, class_id, confidence, x, y, x_plus_w, y_plus_h):

label = str(classes[class_id])

color = COLORS[class_id]

cv2.rectangle(img, (x,y), (x_plus_w,y_plus_h), color, 2)

cv2.putText(img, label, (x-10,y-10), cv2.FONT_HERSHEY_SIMPLEX, 0.5, color, 2)

image=img[y:y_plus_h,x:x_plus_w]
cv2.imshow('crop',image)
cv2.imwrite("cropped.jpg",image)

image = cv2.imread(args.image)
Width = image.shape[0]
Height = image.shape[1]
scale_factor = 0.00392
classes = None

with open(args.classes, 'r') as f:
classes = [line.strip() for line in f.readlines()]

COLORS = np.random.uniform(0, 255, size=(len(classes), 3))

model = cv2.dnn.readNet(args.weights, args.config)

blob = cv2.dnn.blobFromImage(image, scale_factor, (416,416), (0,0,0), True, crop=False)

model.setInput(blob)

outputs = model.forward(get_output(model))

class_ids = []
confidences = []
bounding_boxes = []
conf_threshold = 0.5
nms_threshold = 0.4

for output in outputs:
for detection in output:
scores = detection[5:]
class_id = np.argmax(scores)
confidence = scores[class_id]
if confidence > 0.5:
center_x = int(detection[0]*Width)
center_y = int(detection[1]*Height)
w = int(detection[2] * Width)
h = int(detection[3] * Height)
x = center_x - w / 2
y = center_y - h / 2
class_ids.append(class_id)
confidences.append(float(confidence))
bounding_boxes.append([x,y,w,h])

indices = cv2.dnn.NMSBoxes(bounding_boxes,confidences,conf_threshold,nms_threshold)

for i in indices:
i = i[0]
box = bounding_boxes[i]
x,y,w,h = box[0],box[1],box[2],box[3]
draw_preds(image,class_ids[i],confidences[i],round(x),round(y),round(x+w),round(y+h))

cv2.imshow("license plate detection",image)
cv2.waitKey()

cv2.imwrite("plate-detection.jpg",image)
cv2.destroyAllWindows()

Below Error: //kindly help anyone. what is the wrong with this code
D:\pythonall\ANPR-master>python test.py -i /path/to/image -c /path/to/config_file -w /path/to/weights/ -cl /path/to/obj.names
[ WARN:0@0.020] global D:\a\opencv-python\opencv-python\opencv\modules\imgcodecs\src\loadsave.cpp (239) cv::findDecoder imread_('/path/to/image'): can't open/read file: check file path/integrity
Traceback (most recent call last):
File "D:\pythonall\ANPR-master\test.py", line 43, in
Width = image.shape[0]
AttributeError: 'NoneType' object has no attribute 'shape'