OpenCV
Download source code (GitHub): https://github.com/pirahansiah/
https://www.tiziran.com/topics/opencv
C++
Python
NuGet - OpenCV 5 beta
NuGet packages for OpenCV 5 - Static Library for Visual Studio 2019 and 2022
https://www.tiziran.com/topics/opencv
Install and setup your OpenCV project in just 5 minutes
Config your visual studio project for computer vision application
static opencv library for visual studio 2022 by using NuGet package manager just in few minutes
https://www.youtube.com/watch?v=AEqZO_fZHZ8
#YouTube #OpenCV5 #cpp #vs22
Test, C++, Computer Vision, Image Processing,
download source code (GitHub): https://github.com/pirahansiah/
#OpenCV #Farshid_PirahanSiah #tiziran
My NuGet packages comprised of two versions for different VS version.
Visual Studio 2019
https://www.nuget.org/packages/OpenCV5_StaticLib_VS2019_NuGet
Install-Package OpenCV5_StaticLib_VS2019_NuGet -Version 2022.7.7
Visual Studio 2022
https://www.nuget.org/packages/OpenCV5_StaticLib_VS22_NuGet
Install-Package OpenCV5_StaticLib_VS22_NuGet -Version 2022.7.7
cvtest: Computer Vision Test
Unit Test, Integration Test, System Test, Acceptance Test for Computer Vision and Deep Learning
Do you want to test your output of computer vision application which is video or images?
Standard test for computer vision application
There isn't any standard test for computer vision program. I wrote many test by myself and I would like to share some of them here. For example, I write a program to test docker and check the processing time, memory usage, CPU usage, etc. In computer vision application sometime you need to check the output which is the image. How do you want to check it. I write some program to check the output which is the image and compare the ground truth. I check some well known methods such as PSNR, SSIM, Image quality, distortion, brightness, sharpness, etc. Furthermore, I check much different hardware and write some test for computer vision application base on different hardware architecture and Evaluation hardware.
Do you want to know your program Automatically adjusting brightness of image in the right way?, How do you know using generic sharpening kernel to remove blurriness is working?, How to do check FPS process?, Which OCR system work better for your input image?
https://github.com/pirahansiah/cvtest/blob/main/README.md
download source code (GitHub): https://github.com/pirahansiah/
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
Advanced OpenCV techniques:
sub-pixel, floating points, more precise, real-valued coordinates, Changing the contrast and brightness of an image in CV_32FC3 with OpenCV, Tips and Tricks of OpenCV that Nobody Told You
download source code (GitHub): https://github.com/pirahansiah/
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
Advanced OpenCV techniques:
Cross correlation (CC): TM_CCORR
Mean shifted cross correlation (Pearson correlation coefficient): TM_CCOEFF
Normalization: TM_SQDIFF_NORMED, TM_CCORR_NORMED, TM_CCOEFF_NORMED
maximum absolute difference metric (MaxAD), which is also known as the uniform distance metric computeECC() and findTransformECC().
Sum of absolute differences (SAD)
Cross correlation (CC)
find identical regions of an image that match a template, select by giving a threshold
2D convolution
It simply slides the template image over the input image (as in 2D convolution) and compares the template and patch of input image under the template image.
Template matching
> cv2.TM_CCOEFF
> cv2.TM_CCOEFF_NORMED
> cv2.TM_CCORR
> cv2.TM_CCORR_NORMED
< cv2.TM_SQDIFF
< cv2.TM_SQDIFF_NORMED
cv2.minMaxLoc()
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
https://stackoverflow.com/questions/58158129/understanding-and-evaluating-template-matching-methods
Advanced OpenCV techniques: balance white
balance white with OpenCV, Tips and Tricks of OpenCV that Nobody Told You
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
void balance_white(cv::Mat mat) {
double discard_ratio = 0.05;
int hists[3][256];
memset(hists, 0, 3 * 256 * sizeof(int));
for (int y = 0; y < mat.rows; ++y) {
uchar* ptr = mat.ptr<uchar>(y);
for (int x = 0; x < mat.cols; ++x) {
for (int j = 0; j < 3; ++j) {
hists[j][ptr[x * 3 + j]] += 1;
}
}
}
// cumulative hist
int total = mat.cols * mat.rows;
int vmin[3], vmax[3];
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 255; ++j) {
hists[i][j + 1] += hists[i][j];
}
vmin[i] = 0;
vmax[i] = 255;
while (hists[i][vmin[i]] < discard_ratio * total)
vmin[i] += 1;
while (hists[i][vmax[i]] > (1 - discard_ratio) * total)
vmax[i] -= 1;
if (vmax[i] < 255 - 1)
vmax[i] += 1;
}
for (int y = 0; y < mat.rows; ++y) {
uchar* ptr = mat.ptr<uchar>(y);
for (int x = 0; x < mat.cols; ++x) {
for (int j = 0; j < 3; ++j) {
int val = ptr[x * 3 + j];
if (val < vmin[j])
val = vmin[j];
if (val > vmax[j])
val = vmax[j];
ptr[x * 3 + j] = static_cast<uchar>((val - vmin[j]) * 255.0 / (vmax[j] - vmin[j]));
}
}
}
}
reference http://www.ipol.im/pub/art/2011/llmps-scb/
https://gist.github.com/tomykaira/94472e9f4921ec2cf582
Advanced OpenCV techniques: contrast and brightness
sub-pixel, floating points, more precise, real-valued coordinates, Changing the contrast and brightness of an image in CV_32FC3 with OpenCV, Tips and Tricks of OpenCV that Nobody Told You
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
showImage.convertTo(showImage, CV_32FC3);
double alpha = 2.0; /*< Simple contrast control */
int beta = 100; /*< Simple brightness control */
for (int y = 0; y < showImage.rows; y++) {
for (int x = 0; x < showImage.cols; x++) {
for (int c = 0; c < showImage.channels(); c++) {
showImage.at<cv::Vec3f>(y, x)[c] =cv::saturate_cast<float>(alpha * showImage.at<cv::Vec3f>(y, x)[c] + beta);
}
}
}
showImage.convertTo(showImage, CV_8UC3);
cv::imshow("Changing the contrast and brightness of an image! ", showImage);
cv::waitKey(0);
based on https://docs.opencv.org/3.4/d3/dc1/tutorial_basic_linear_transform.html
Advanced subpixel techniques: Shift image content
sub-pixel, floating points, mesh grid, remap, more precise, real-valued coordinates, moving image pixel, Shift image content with OpenCV, Tips and Tricks of OpenCV that Nobody Told You
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
Mesh grid float
static void meshgrid_float(const cv::Mat& xgv, const cv::Mat& ygv,
cv::Mat1f& X, cv::Mat1f& Y)
{
cv::repeat(xgv.reshape(1, 1), ygv.total(), 1, X);
cv::repeat(ygv.reshape(1, 1).t(), 1, xgv.total(), Y);
}
static void meshgrid_map_float(const cv::Range& xgv, const cv::Range& ygv,
cv::Mat1f& X, cv::Mat1f& Y)
{
std::vector<float> t_x, t_y;
for (int i = xgv.start; i <= xgv.end; i++) t_x.push_back(i);
for (int i = ygv.start; i <= ygv.end; i++) t_y.push_back(i);
meshgrid_float(cv::Mat(t_x), cv::Mat(t_y), X, Y);
}
mesh grid int
static void meshgrid(const cv::Mat& xgv, const cv::Mat& ygv,
cv::Mat1i& X, cv::Mat1i& Y)
{
cv::repeat(xgv.reshape(1, 1), ygv.total(), 1, X);
cv::repeat(ygv.reshape(1, 1).t(), 1, xgv.total(), Y);
}
static void meshgridTest(const cv::Range& xgv, const cv::Range& ygv,
cv::Mat1i& X, cv::Mat1i& Y)
{
std::vector<int> t_x, t_y;
for (int i = xgv.start; i <= xgv.end; i++) t_x.push_back(i);
for (int i = ygv.start; i <= ygv.end; i++) t_y.push_back(i);
meshgrid(cv::Mat(t_x), cv::Mat(t_y), X, Y);
}
main:
cv::Mat1f XF, YF;
//for int
//meshgrid_map_float(cv::Range(0, cols_main), cv::Range(0, rows_main), XF, YF);
//for float
meshgrid_map_float(cv::Range(0, cols_main-1), cv::Range(0, rows_main-1), XF, YF);
for (int rowsImage = 0; rowsImage < rows_main; ++rowsImage) {
for (int colsImage = 0; colsImage < cols_main; ++colsImage) {
XF.at<float>(rowsImage, colsImage) += offset1;
YF.at<float>(rowsImage, colsImage) += offset2;
}
}
cv::remap(convert_img_i, dst, XF, YF, cv::INTER_LINEAR);
if (show)
{
cv::Mat resizedImage = dst.clone();
dst.convertTo(resizedImage, CV_8UC3);
cv::resize(resizedImage, resizedImage, cv::Size(), 0.5, 0.5);
std::string nameWindow = " meshgrid and remap in float ";
cv::imshow(nameWindow, resizedImage);
cv::waitKey(0);
}
Tips and Tricks of OpenCV that Nobody Told You
Tips and Tricks of OpenCV that Nobody Told You
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
Tricks
cv::multiply(outMat, cv::Scalar(gain, gain, gain), outMat); //color
cv::multiply(outMat, cv::Scalar(gain), outMat); //grayscale
//copy small Mat to bigger Mat
cv::Rect roi( cv::Point( originX, originY ), smallImage.size() );
smallImage.copyTo( bigImage( roi ) );
Tips
copy mat to vector need clone()
Save results
save image in float
cv::imwrite("image.exr", MatImage);
save image in uncompressed format :
cv::imwrite("fa.tiff", resizedImage, { cv::IMWRITE_TIFF_COMPRESSION, 1,cv::IMWRITE_TIFF_XDPI, 300,cv::IMWRITE_TIFF_YDPI,300 });
cv2.imwrite(filename, array, params=(cv2.IMWRITE_TIFF_COMPRESSION, 1)) # None
cv2.imwrite(filename, array, params=(cv2.IMWRITE_TIFF_COMPRESSION, 5)) # LZW
cv2.imwrite(filename, array, params=(cv2.IMWRITE_TIFF_COMPRESSION, 8)) # Adobe Deflate
cv2.imwrite(filename, array, params=(cv2.IMWRITE_TIFF_COMPRESSION, 32946)) # Deflate
cv::imwrite("far.png", resizedImage, { cv::IMWRITE_PNG_COMPRESSION, 0 });
Save images in streaming
int64 t0 = cv::getTickCount();
std::string fileName= "fashid_"+std::to_string(t0)+ ".png";
cv::imwrite(fileName, cimMat, { cv::IMWRITE_PNG_COMPRESSION, 0 });
Save file name:
std::filesystem::path p = std::filesystem::path(files[i]).filename();
std::string imgFile = savePath + "/" + p.string() + ".tiff";
cv2.imwrite(filename, array, params=(cv2.IMWRITE_TIFF_COMPRESSION, 1)) ;
Error
Exception thrown at 0x00007FFB5CB21636 (vcruntime140d.dll) in farshid.exe: 0xC0000005: Access violation writing location 0x000002B09BAC4000.
check the size of Mat
cv::Mat meanImages = cv::Mat::zeros(rows_main, cols_main, CV_32F);
cv::Mat meanImages = cv::Mat::zeros(farshidMat.size(), CV_32F);
Linker Tools Error LNK2038 & Linker Tools Error LNK2001; Severity Code Description Project File Line Suppression State Error LNK2038 mismatch detected for '_ITERATOR_DEBUG_LEVEL': value '2' doesn't match value '0' in Source.obj ; Severity Code Description Project File Line Suppression State Error LNK2038 mismatch detected for 'RuntimeLibrary': value 'MTd_StaticDebug' doesn't match value 'MT_StaticRelease'
the link files are not match based on release or debug mode.
Testing for OpenCV Projects
Test, C++, Computer Vision, Image Processing,
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
sample code in C++:
Arrange, Act and Assert (AAA) Pattern
Google C++ Test Framework
Assertions Types and Test Fixtures
ASSERT_FALSE(frame.empty());
ASSERT_NO_THROW(cap >> img);
ASSERT_FALSE(img.empty()) << "idx=" << idx;
Tricks
embedded system, keep the software as small as possible, Embedding static elements in your application,
https://gstreamer.freedesktop.org/documentation/installing/index.html?gi-language=c
Tips
copy mat to vector need clone()
Example
#include <cassert>
assert(!im.empty());
assert(x.size()==y.size());
assert(x.size()>2);
#ifdef _DEBUG
#endif
#if true
#else
#endif
YouTube
Install and setup your OpenCV project in just 5 minutes
Config your visual studio project for computer vision application
static opencv library for visual studio 2022 by using NuGet package manager just in few minutes
https://www.youtube.com/watch?v=AEqZO_fZHZ8
#YouTube #OpenCV5 #cpp #vs22
Test, C++, Computer Vision, Image Processing,
more: https://www.tiziran.com/topics/opencv
#OpenCV #Farshid_PirahanSiah #tiziran
https://github.com/xiaohongchen1991/meshgen
A set of C++ APIs are provided to mimic the same behaviors as the MATLAB function "linspace" and "meshgrid".
Must-Read Books of All Time in Computer Vision and Machine Learning
