Add Radon transform function to ximgproc #3090

kuloPo · 2021-10-26T11:15:25Z

This function calculates the Hough Space of a given image in any range.
Hough Transform is a discrete implementation of Radon Transform.

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

I agree to contribute to the project under Apache 2 License.
To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV
The PR is proposed to proper branch
There is reference to original bug report and related work
There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
The feature is well documented and sample code can be built with the project CMake

alalek · 2021-10-26T12:27:00Z

modules/ximgproc/include/opencv2/ximgproc/hough_space_transform.hpp

+* with type CV_32SC1 by default.
+*
+*/
+CV_EXPORTS_W void HoughSpaceTransform(InputArray src,


What is wrong with HoughLines?

HoughLines only returns lines detected in images. Hough Space can be used in other ways like comparing similarity between images, and it has some advantages over comparing histograms or pixels directly.

After a search I found Hough Detection is using Radon Transform to detect shape in image. (Described here https://www.osti.gov/doepatents/biblio/4746348 ). What I implemented is more like Radon Transform (https://en.wikipedia.org/wiki/Radon_transform)
Should I change my function name and commit to the same pull request?

AleksandrPanov · 2021-11-01T19:49:44Z

I compared the current version of Radon Transform with the scikit-image radon version based on scikit-image example.

The current version always crops the image when it is rotated.
The current version gives a slightly different result compared to the scikit-image version (this may be due to different interpolation or different rounding.). Need add more tests to check the meaning of the result (for example tests from radon.py.txt).
It might be helpful to add CV_32FC1 for src/dst.

radon.py.txt

kuloPo · 2021-11-07T02:21:45Z

Updates:

Change function name to RadonTransform
Fix always cropping corner when rotate
transpose the output - now each column is the integral
add support for float number

The small difference may caused by:

rounding from rad to deg in scikit
different rotation method
copying image to a bigger background to capture the rotated image

I wrote two more cases to test data in corners
radon.py.txt

AleksandrPanov · 2021-11-08T17:05:33Z

Thank you, I think it got better after your update:

:

AleksandrPanov · 2021-11-08T17:30:24Z

LGTM + minor comments:

this patch should go into 4.x branch (only bug fixes get into 3.4 branch).
rebase your commits from 3.4 onto 4.x branch. For example:
git rebase -i --onto upstream/3.4 upstream/master
(check list of your commits, save and quit (Esc + "wq" + Enter)
where upstream is configured by following this GitHub guide and fetched (git fetch upstream).
push rebased commits into source branch of your fork (with --force option)

Note: no need to re-open PR, apply changes "inplace".

fix always cropping corner when rotate transpose the output - now each column is integral add support for float number add comment

kuloPo · 2021-11-08T23:48:27Z

The branch is rebased to 4.x

alalek

@kuloPo Thank you for updates!

Please take a look on the comments below.

alalek · 2021-11-09T02:32:41Z

modules/ximgproc/perf/perf_radon_transform.cpp

+namespace opencv_test {
+    namespace {
+
+        typedef tuple<Size, MatType> RadonTransformPerfTestParam;


Please avoid indentation in namespaces

alalek · 2021-11-09T02:33:08Z

modules/ximgproc/samples/radon_transform_demo.cpp

+
+int main() {
+	cv::Mat src = cv::imread("peilin_plane.png", cv::IMREAD_GRAYSCALE);
+	cv::Mat radon;


Please use 4 spaces for indentation (no tabs)

alalek · 2021-11-09T02:34:15Z

modules/ximgproc/samples/radon_transform_demo.cpp

+#include <opencv2/ximgproc/radon_transform.hpp>
+
+int main() {
+	cv::Mat src = cv::imread("peilin_plane.png", cv::IMREAD_GRAYSCALE);


cv::

In OpenCV samples we add using namespace cv; after includes and removing all cv:: prefixes.

alalek · 2021-11-09T02:36:15Z

modules/ximgproc/test/test_radon_transform.cpp

+    Mat radon;
+    cv::ximgproc::RadonTransform(src, radon);
+
+    ASSERT_EQ(radon.rows, 363);


_EQ

uses different order of parameters: (expected, actual).

Signature for _EQ is ASSERT_EQ(expected_reference, actual_result);.
Correct order of parameters are required to emit valid error messages.

Reference: https://github.com/opencv/opencv/blob/4.0.0/modules/ts/include/opencv2/ts/ts_gtest.h#L8196-L8200

GTEST_API_ AssertionResult EqFailure(const char* expected_expression, const char* actual_expression, const std::string& expected_value, const std::string& actual_value, bool ignoring_case);

alalek · 2021-11-09T02:40:16Z

modules/ximgproc/perf/perf_radon_transform.cpp

+
+            declare.in(src, WARMUP_RNG);
+
+            TEST_CYCLE_N(3)


TEST_CYCLE_N

is misused here. No need to specify amount of inner samples here.

Please use:

TEST_CYCLE()

or PERF_SAMPLE_BEGIN() + PERF_SAMPLE_END()

alalek · 2021-11-09T02:44:59Z

modules/ximgproc/test/test_radon_transform.cpp

+    Mat radon;
+    cv::ximgproc::RadonTransform(src, radon);
+
+    ASSERT_EQ(radon.at<int>(0, 0), 0);


Before using .at<int> it makes sense to validate type.

ASSERT_EQ(CV_32SC1, radon.type()); EXPECT_EQ(0, radon.at<int>(0, 0));

(prefer to use EXPECT_ for non-critical failures - e.g. code below would not crash)

kuloPo · 2021-11-09T08:19:29Z

All the issues are fixed.

AleksandrPanov

👍

alalek reviewed Oct 26, 2021

View reviewed changes

kuloPo requested a review from alalek October 28, 2021 05:52

asmorkalov requested a review from AleksandrPanov October 29, 2021 09:37

kuloPo changed the title ~~Add hough space transform function to ximgproc~~ Add Radon transform function to ximgproc Nov 7, 2021

kuloPo and others added 12 commits November 8, 2021 22:02

resolve rebash conflict

d3af10b

add test for hough_space_transform

db9dd78

add perf for hough_space_transform

6d3a090

add sample for hough_space_transform

ef201f7

fix compatible issue and trailing space

7c01f94

fix EOF issue

c65d6a7

resolve rebash conflict

a2cb365

update radon transform

88789d9

fix always cropping corner when rotate transpose the output - now each column is integral add support for float number add comment

add float type to perf test

7ab5b29

add float type to accu test

05eb729

update document

99cdad6

fix trailing space

36275ca

kuloPo force-pushed the add-hough_space_transform branch from 2a7f0ba to 36275ca Compare November 8, 2021 22:22

kuloPo changed the base branch from 3.4 to 4.x November 8, 2021 22:23

resolve rebase conflict

9d0b434

alalek reviewed Nov 9, 2021

View reviewed changes

Resolve coding style issues

7d08471

AleksandrPanov approved these changes Nov 9, 2021

View reviewed changes

alalek assigned AleksandrPanov Nov 9, 2021

alalek merged commit e94ec40 into opencv:4.x Nov 9, 2021

alalek mentioned this pull request Dec 30, 2021

(5.x) Merge 4.x #3142

Merged

alalek mentioned this pull request Feb 22, 2022

(5.x) Merge 4.x #3179

Merged

mshabunin mentioned this pull request Dec 6, 2024

Radon transform #549

Closed

Add Radon transform function to ximgproc #3090

Add Radon transform function to ximgproc #3090

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kuloPo commented Oct 26, 2021 •

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