CODEWITHSUNDEEP
pythonopencvimage-processing
pallavi
pallavi

Reputation: 153

Resizing an image in open cv

I am kind of new to opencv and image processing. I was trying out this code which I found on pyimagesearch.com. I resized the image to a height of 500 pixels to perform edge detection and to find contours. 

r = 500.0 / image.shape[1]
dim = (500,int(image.shape[0] * r))
image = cv2.resize(image,dim,interpolation = cv2.INTER_AREA)
ratio  = image.shape[0] /500.0

Again, I multiply the processed image with the ratio( so that changes are made w.r.t the original image)

warped = four_point_transform(orig,screenCnt.reshape(4,2)*ratio)
r = 500.0 / warped.shape[1]
dim = (500,int(warped.shape[0] * r))

warped = cv2.resize(warped,dim,interpolation = cv2.INTER_AREA)
cv2.imshow("Perspective Transform",warped)

After this, what results I am getting is somewhat like this Image. Only some part of the image is visible and I am unable to see the rest of the image. Please help me. Thanks!

Upvotes: 4

Views: 4590

Answers (2)

Airman00
Airman00

Reputation: 336

If you want a really easy way to upsize or downsize your image, use pyrUp and pyrDown.

http://docs.opencv.org/2.4/doc/tutorials/imgproc/pyramids/pyramids.html

imageSmall = cv2.pyrDown(image) # make image smaller
imageLarger = cv2.pyrUp(image) # make image larger

Upvotes: 0

Joan Charmant
Joan Charmant

Reputation: 2022

It seems to me that you are mixing width and height.

For a regular image image.shape[] will give you height, width and channels, in that order.

So it should probably look like:

newHeight = 500.0
oldHeight = image.shape[0]
oldWidth = image.shape[1]
r = newHeight / oldHeight
newWidth = int(oldWidth * r)
dim = (newHeight, newWidth)
image = cv2.resize(image, dim, interpolation = cv2.INTER_AREA)
aspectRatio = image.shape[1] / image.shape[0]

Upvotes: 2

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