CODEWITHSUNDEEP
pythonopencvcomputer-vision
Andrew Ferruolo
Andrew Ferruolo

Reputation: 35

Video with certain pixel height, width in opencv

I’m trying to use opencv to take a photo on a 1080p camera, however, only want the photo to be 224x224 pixels. How can I use opencv to do this.

I currently have the following code:

Import cv2
Cap = cv2.VideoCam(0)
Cap.set(3, 224)
Cap.set(4, 224)

Ret, frame = cap.read()

However when I look at the shape of frame, it is not (224, 224, 3). Could someone please help me figure out how to make it output the dimensions of pixels I want

Upvotes: 2

Views: 1449

Answers (3)

Mark Setchell
Mark Setchell

Reputation: 207405

When you say you want a 224x224 image, it depends what you mean. If we start with this image which is 1920x1080, you might want:

  • (A) - the top-left corner, highlighted in magenta
  • (B) - the central 224x224 pixels, highlighted in blue
  • (C) - the largest square, resized down to 224x224, highlighted in red
  • (D) - the entire image distorted to fit in 224x224

enter image description here

So, assume in the following that you have read your frame from the camera into a variable called im using something like:

...
...
ret, im = cap.read()

If you want (A), use:

# If you want the top-left corner
good = im[:224, :224]

enter image description here

If you want (B), use:

# If you want the centre
x = h//2 - 112
y = w//2 - 112
good = im[x:x+224, y:y+224]

enter image description here

If you want (C), use:

# If you want the largest square, scaled down to 224x224
y = (w-h)//2
good = im[:, y:y+h]
good = cv2.resize(good,(224,224))

enter image description here

If you want (D), use:

# If you want the entire frame distorted to fit 224x224
good = cv2.resize(im,(224,224))

enter image description here

Keywords: Image processing, video, 1920x1080, 1080p, crop, distort, largest square, central portion. top-left, Python, OpenCV, frame, extract.

Upvotes: 5

Ziri
Ziri

Reputation: 736

import cv2
video_capture = cv2.VideoCapture(0)

while video_capture.isOpened():
      video_capture.set(cv2.CAP_PROP_FRAME_HEIGHT, 224)
      video_capture.set(cv2.CAP_PROP_FRAME_WIDTH, 224)
      frame = video_capture.read()[1]

      cv2.imshow('frame', frame)
      if cv2.waitKey(1) == ord("q"):
         break

to get the current size use : 

cap.get(cv2.CAP_PROP_FRAME_WIDTH)
cap.get(cv2.CAP_PROP_FRAME_HEIGHT)

if that didn't work then Opencv doesn't have access to the (width, height )features of the camera you are using.

Upvotes: 1

JeanExtreme002
JeanExtreme002

Reputation: 231

This is quite simple, just use the cv2.resize(frame, size) function. Example:

import cv2

cam = cv2.VideoCapture(0)  # My camera is 640x480
size = (200,200)           # The "size" parameter must be a tuple.

while True:
    frame = cam.read()[1]
    new_frame = cv2.resize(frame,size)  # Resizing the frame ...

    cv2.imshow('sla',new_frame)

    if cv2.waitKey(1) == ord("q"):
        break

cv2.destroyAllWindows()

Upvotes: 0

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