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2020-12-03 07:08:30 -0600 commented answer Pixel-wise matrix multiplication

berak is right. Use cv::transform, you misunderstand the documentation.

2020-11-01 07:51:13 -0600 commented question How to undistort image along single axis

If you have your distortion maps, remap doesn't care what you give it. So pass an iota image (rows or cols) for the dime

2020-10-20 12:26:53 -0600 commented question Is there a way to make this template matching faster?

Look at using FFT/DFTs. They transform convolution to element-wise multiplication, offering a huge speedup over spatial

2020-10-12 15:06:07 -0600 commented question Track black object with optical flow

Look at median flow paper. There is apparently no benefit to using GFFT or FAST. You must also use more than one feature

2020-10-09 09:43:47 -0600 commented question Calculating motion of Spacecraft/Camera

The number of pyramid levels may be insufficient for the distances required going from image 1 to image 3. You might als

2020-10-09 09:43:28 -0600 commented question Calculating motion of Spacecraft/Camera

You number of pyramid levels may be insufficient for the distances required going from image 1 to image 3. You might als

2020-10-09 09:41:07 -0600 commented question Drawing several circles in an additive way

You could do blending over ROIs, maintaining a total light image. So rather than call cv::circle() directly on the image

2020-10-09 09:30:58 -0600 commented question ORB Keypoints Minimum distance?

Do you need a multi-scale detector? Are your images at the same scale? If so, just use FAST for detection and FREAK for

2020-10-08 08:13:40 -0600 commented question ORB Keypoints Minimum distance?

Orb does multi-scale FAST, are you sure the points in close proximity aren't at different scales? Is non-maxima suppress

2020-10-01 11:36:14 -0600 commented question crash in Mat::release()

Why do you put & in front of channel argument? There is usually no reason to pass cv::Mat pointers.

2020-09-30 19:20:28 -0600 commented question crash in Mat::release()

Do not call release(), let it go out of scope.

2020-09-30 19:18:00 -0600 edited question crash in Mat::release()

crash in Mat::release() Hi, I have a function that creates a histogram: double median_(const cv::Mat& channel) {

2020-09-28 06:49:21 -0600 commented question I wanted to export my satellite image to a particular zoom level

Have you tried using GDAL directly rather than OpenCV? It will offer you all possible features compared to what little i

2020-09-21 15:00:04 -0600 commented question How to pre-process images for OCR ?

A Generalization of Otsu's Method and Minimum Error Thresholding. See the end of the paper for Python code.

2020-09-16 09:00:43 -0600 commented question world coordinates from object detection

If the camera is (0,0,0) of your coordinate frame, use cv::reprojectImageTo3D(). This requires the Q matrix from calibra

2020-09-14 18:55:36 -0600 commented question Mat of int64

Try something similar to the following: // // This is a deep copy, OpenCV has no CV_64(U|S) types, only CV_32S: // cv::

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2020-09-14 14:35:22 -0600 commented question Mat of int64

As I said above, there is no int64 support in cv::Mat. Have you measured the performance costs of casting to int32? It m

2020-09-14 11:42:23 -0600 commented question world coordinates from object detection

Please elaborate on 'world coordinates'.

2020-09-10 07:22:28 -0600 commented question Convert Images (cv::Mat)

You need to scale the results, so multiply or divide by 255 or 65536, etc. Look more closely at that function.

2020-09-09 08:29:23 -0600 commented question How to use opencv demosaicing

It that case it looks right to me except that you might have rows and cols swapped. Are you seeing a problem? If so, can

2020-09-08 18:49:23 -0600 commented question How to use opencv demosaicing

If you can capture from the camera at 16-bits (even if dynamic range is 12-bits), that might be the simplest and best op

2020-09-08 14:02:30 -0600 commented question How to use opencv demosaicing

If your raw data is 12-bit pixels, interpreting them as 16-bits is not going to work and may seg fault. You need to firs

2020-09-05 09:22:39 -0600 commented question Mat of int64

At present there is no CV_64S support, so your best option is to convert/cast to CV_32S for down stream processing.

2020-09-01 09:28:23 -0600 commented question Haar Cascade or ...? OpenCV detection

Everyone will answer "deep learning", Haar cascades will almost certainly not work for anything close to what you say yo

2020-08-24 08:19:45 -0600 commented answer normalization not working

Your image is 8-bits, 0-255, so normalizing with minmax 0-255 will likely do nothing. 0 will still be 0 and 255 will sti

2020-08-24 08:15:29 -0600 commented question One Hot Encode function

No, this is how to make best use of the OpenCV API to get what I want with simplicity.

2020-08-22 08:18:50 -0600 commented answer normalization not working

The image is 8-bits so values should already be 0-255, right? The operation won't change pixel values.

2020-08-21 09:34:24 -0600 commented question Crop/approximate contours

A few erodes followed by some dilates will coarsen the contour.

2020-08-18 10:30:38 -0600 commented question One Hot Encode function

@berak, yes, this could be a 1D loop assuming continuous. The reason is to do this is for semantic segmentation. I have

2020-08-18 10:29:26 -0600 commented question One Hot Encode function

@berak, yes, this could be a 1D loop assuming continuous. The reason is to do this is for semantic segmentation. I have

2020-08-18 09:42:15 -0600 asked a question One Hot Encode function

One Hot Encode function I have a matrix where each element is a class ID. I need to transform this matrix into a one-hot

2020-08-07 09:57:47 -0600 commented question Optimize CSRT tracker?

Another option is tracking by detection, where you run your insect detector every X frames and associate new detections

2020-08-07 09:53:16 -0600 commented question Disable file system cache during imwrite

Is this really an OpenCV issue? What do you mean by system buff/cache? Memory? Can you post a minimal example of your co

2020-08-05 22:50:17 -0600 received badge  Good Answer (source)
2020-07-27 08:25:50 -0600 commented question OpenCV Noisy Disparity Map from Stereo Setup

I was just wondering why resize if not for the disparity computation, but maybe they are very large and want to see them

2020-07-25 11:56:14 -0600 commented question OpenCV Noisy Disparity Map from Stereo Setup

They are also vertically misaligned. Recalibrate and visualize the undistorted and rectified images as an anaglyph to ve

2020-07-25 09:17:53 -0600 commented question OpenCV Noisy Disparity Map from Stereo Setup

Your left image is out of focus. You don't used resized images in the SGBM computation? Your SGBM parameters are a littl

2020-07-20 12:02:58 -0600 commented question Calculate (ORB) descriptors for arbitrary image points

Take a look at the source code. For instance, copy and modify the function ICAngles to suit your needs.

2020-07-06 09:14:18 -0600 commented question How to calculate disparity image for Left to Right from Right to Left andvice versa?

DSI = Disparity Space Image (HxWxD). This is the volume you aggregate over for a smoothed cost estimate. This is also th

2020-07-02 14:04:00 -0600 commented question How to calculate disparity image for Left to Right from Right to Left andvice versa?

If you have a DSI, every comparison you need to do R-L you already did for L-R.

2020-07-02 07:58:49 -0600 commented question How to calculate disparity image for Left to Right from Right to Left andvice versa?

If you have a DSI, every comparison you need to R-L you already did for L-R.

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2020-06-11 15:36:21 -0600 edited answer how could I change memory layout from hwc to chw ?

The following has worked well for me, with no unnecessary data allocation: void hwc_to_chw(cv::InputArray src, cv::Outp

2020-06-11 15:35:24 -0600 edited answer how could I change memory layout from hwc to chw ?

void hwc_to_chw(cv::InputArray src, cv::OutputArray dst) { const int src_h = src.rows(); const int src_w = s

2020-06-11 15:34:09 -0600 edited answer how could I change memory layout from hwc to chw ?

void hwc_to_chw(cv::InputArray src, cv::OutputArray dst) { const int src_h = src.rows(); const int src_w =

2020-06-11 15:32:58 -0600 edited answer how could I change memory layout from hwc to chw ?

void hwc_to_chw(cv::InputArray src, cv::OutputArray dst) { const int src_h = src.rows(); const int src_w =

2020-06-11 14:54:12 -0600 marked best answer Broadcast single channel to N-channels

Is there an OpenCV function to take a single channel image and extend it to N-channels, copying/repeating the pixel value to all channels, something like a pixel-wise broadcast?

I need to be able to per-element multiply a single channel image with an n-channel image and the only way to do this with high-level function calls is to extend/repeat the single channel image to match the dimensions of my n-channel image. Can I achieve this with a cv::Mat from cv::Mat::reshape() passed to cv::repeat()? Can I achieve this with cv::transform()?

2020-06-11 14:54:02 -0600 answered a question Broadcast single channel to N-channels

I solved this using cv::transform(), see the example below to extend the single_channel image to n channels. cv::Ma

2020-06-11 14:46:00 -0600 answered a question how could I change memory layout from hwc to chw ?

void hwc_to_chw(cv::InputArray src, cv::OutputArray dst) { const int src_h = src.rows();