shobhitpuri's profile - activity

okay. I get it. Thanks. Also I'm curious to know that even if I am not converting 'img' in the range of [0..1], it seems to work fine. How is that? imf = np.float32(img) # float conversion dst = cv2.dct(imf) # the dct img = np.uint8(dst) # convert back

Thanks for the answer. When I am checking the values of the 'dst' variable, they are coming out to be more than 1. As a result the 'img' has values > 255? Can you please explain this? It would be really helpful.

When I used 'False' in Normalized, I was receiving and empty white image. Then I used 'True' after reading the wiki article here: http://en.wikipedia.org/wiki/Kernel_%28image_processing%29 It says: For Blur, you need to Normalize the image. Normalization ensures that the pixel values in the output image are of the same relative magnitude as those in the input image.

I was able to see the image saved after the boxFilter.

@Guanta is extremely right. I got that working as follows:

cv2.boxFilter(imgcv1, 0, (7,7), imgcv1, (-1,-1), False, cv2.BORDER_DEFAULT)

Thanks for the reply @Guanta. You are extremely right. Finally, I did the same and got that working.

Thanks for your comment. You're right. Actually I've been trying to look around for the same thing. Have a look at this post: http://stackoverflow.com/questions/7931382/calculate-discrete-cosine-transformation-of-image-with-opencv . Please let me know if you get this working. I'll post the solution if I am able to get it running .

I've been trying to figure out a way of getting a DCT of image. After getting the image and doing a bunch of filtering, I want to calculate DCT. Following is the code sniplet:

imgcv1 = cv2.split(imgcv)[0] 
cv2.boxFilter(imgcv1, 0, (7,7), imgcv1, (-1,-1), False, cv2.BORDER_DEFAULT)
#resize image to 32x32
cv2.resize( imgcv1, (32, 32 ) ,imgcv1)

I've been trying to play around with the description given here but no success. When I tried something like:

dst = cv2.dct(imgcv1)

I get an error like:

cv2.error: /build/buildd/opencv-2.3.1/modules/core/src/dxt.cpp:2247: error: (-215) type == CV_32FC1 || type == CV_64FC1 in function dct

How can I get the dct? I would be grateful for your help.

I am having following error when I use the boxFilter function:

SystemError: new style getargs format but argument is not a tuple

Here is the code sniplet:

//After downloading image from url, I process it as follows
imgcv = cv2.cvtColor(np.asarray(im), cv.CV_RGB2YCrCb)
#Get the channel 0 
imgcv1 = cv2.split(imgcv)[0] 
cv2.boxFilter(imgcv1, 1, 7, data, (1,1), 0, cv2.BORDER_DEFAULT)

It says the argument is not a tuple. How to make it into tuples? I tried to search a lot but no helpful results. I am a beginner in openCV and in python. Here is the definition of the filter:

cv2.boxFilter(src, ddepth, ksize[, dst[, anchor[, normalize[, borderType]]]]) → dst
Parameters: 
    src – Source image.
    dst – Destination image of the same size and type as src .
    ksize – Smoothing kernel size.
    anchor – Anchor point. The default value Point(-1,-1) means that the anchor is at the kernel center.
    normalize – Flag specifying whether the kernel is normalized by its area or not.
    borderType – Border mode used to extrapolate pixels outside of the image.