Finnish's profile - activity

@pklab Thanks it is clear but I dont see where "J = I(x,y) - AVG(I)" comes from, where does it say on the documentation or formula we have to subtract AVG(I) or AVG(U) to get U,J?

@berak Thanks a lot!

@berak now it worked, can you please tell me why 255 and not another value? How can I further manipulate the result? What would be its original form?`also can you please check my final question! pretty please!

@berak When I used "result.convertTo(result, CvType.CV_8U);" the result image was still black and not changed.

@berak also I dont see convertTo() on the tutorial...

@berak "result.convertTo(result, CvType.CV_8U);" ? Did not work... could you please give some code example?

I have a working java code for template matching as below:

import org.opencv.core.Core;
import org.opencv.core.Core.MinMaxLocResult;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Point;
import org.opencv.core.Scalar;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;


class MatchingDemo {
public void run(String inFile, String templateFile, String outFile, int match_method) {
    System.out.println("\nRunning Template Matching");

    Mat img = Highgui.imread(inFile);
    Mat templ = Highgui.imread(templateFile);

    // / Create the result matrix
    int result_cols = img.cols() - templ.cols() + 1;
    int result_rows = img.rows() - templ.rows() + 1;
    Mat result = new Mat(result_rows, result_cols, CvType.CV_32FC1);

    // / Do the Matching and Normalize
    Imgproc.matchTemplate(img, templ, result, match_method);
    Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1, new Mat());

    // / Localizing the best match with minMaxLoc
    MinMaxLocResult mmr = Core.minMaxLoc(result);

    Point matchLoc;
    if (match_method == Imgproc.TM_SQDIFF || match_method == Imgproc.TM_SQDIFF_NORMED) {
        matchLoc = mmr.minLoc;
    } else {
        matchLoc = mmr.maxLoc;
    }

    // / Show me what you got
    Core.rectangle(img, matchLoc, new Point(matchLoc.x + templ.cols(),
            matchLoc.y + templ.rows()), new Scalar(0, 255, 0));

    Core.rectangle(result, matchLoc, new Point(matchLoc.x + templ.cols(),
            matchLoc.y + templ.rows()), new Scalar(0, 255, 0));

    // Save the visualized detection.
    System.out.println("Writing "+ outFile);
    Highgui.imwrite("pics/colored_original.png", img);
    Highgui.imwrite("pics/newresult2.png", result);

 }
}

I want to see the gray blurry Matching Result picture as on OpenCV documentation

The code is almost identical with template matching documentation here

The variable should be "result" right? and "newresult2.png" but all I see is a black image and nothing else but the "colored_original.png" comes out very good, the match area is correct. What am I doing wrong or what is missing?

@thdrksdfthmn I don't have a choice, it must be this way for now, I just want to understand the formula...

This template image below gives always 1.0:

best matching result in every source image. @pklab said here it is because the formula of TM_CCOEFF_NORMED returns 0/0 because the template image is constant color and opencv returns 1.0 to avoid match exception, but I still don't get it. I would understand better with an example, lets say template image = 3x4 pixels and source image = 10x12 pixels, could someone put the values in the formula please and show 0/0?

Thanks again! I am searching for a park polygon in the map or lake which are fully green and blue... Could you please add the mathematical operations again, maybe on your answer, how does the result become zero... for my better understanding.

I see so how can I overcome this obstacle? Changing the match method for every specific image will be very troublesome, for the specific case when I use "TM_CCORR_NORMED" the score is 0.93 which is misleading and when I use "TM_SQDIFF_NORMED" I get 0.79, which is promising because it is a bad match, but in general I would like to use "TM_CCOEFF_NORMED" for all images... Also one more question is the template image and source image converted to grayscale and then the math operations take place? Or there is no grayscale conversion?

@pklab thanks for updating the answer, my code I assume is correct because out of 100 images I always find the images and have a good match score, it cant be coincidence, just only this specific full green reference image, always finds at 0,0 and with score 1.0 when using TM_COEFF_NORMED, please feel free to give it a try yourself. Not only this specific green image but on full red, blue etc. colors the story is the same.

I made some tests and TM_COEFF_NORMED was giving the best results so I stick with it, but now you are saying TM_COEFF is Normalized Cross Correlation, so when I use TM_COEFF_NORMED, am I using Normalized Normalized Cross Correlation? Although the 2 images are very different, why does it give 1.0 the best match? and why always on first top left corner? Also if I do normalizing after matching after matching like

 Imgproc.matchTemplate(img, templ, result, match_method);
Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1, new Mat());

Does it become 3 times Normalized? In case of adding the last line of normalization code, I get matchscore 0.0, which satisfies me but with the last line it is always either 1 or 0... nothing else, and sometimes it gives 0 for good matches

@berak may I draw your attention to this question please?

@thdrksdfthmn result is a Mat not very relevant... with the matchscore being "1.0"

Such a shame someone attacking on an opensource project, I hope you get replies back from Alexander asap, can we at least access our questions waiting for moderation?

@berak I already know that and this one http://docs.opencv.org/doc/tutorials/imgproc/histograms/template_matching/template_matching.html but there are just formulas, no explanations.

@berak there are 6 matching methods for Template Matching I dont know which one to choose, which one shall I prefer? According to what cases etc. Im looking for a page where explains all of them detailed, do you have any links by chance explaining the methods?

Until now I have always gotten reasonable results withc matching score, Im using "Imgproc.TM_CCOEFF_NORMED" method for template matching below are the results.

Reference image:

Outcome 1:

MinMaxLocResult mmr = Core.minMaxLoc(result);
maxMatchScore = mmr.maxVal;

Value of maxMatchScore is always 1.0

Outcome 2:

MinMaxLocResult mmr = Core.minMaxLoc(result);
maxMatchScore = mmr.maxVal;

Value of maxMatchScore is always 1.0

1.0 is the best match value, which means the image is %100 identical, but it isn't and on other reference images I get other values, so the program is working but only with this specific reference image I'm getting 1.0 also no matter what in file(source image) I give, it always finds the match on the first search upper left corner. A little bit annoying, I would be glad for your suggestions and comments for improvement because TM_CCOEFF_NORMED gives always the first searched square/rectangle as best match with score 1.0, this cant be correct, on the other hand I also tried TM_CCORR_NORMED and TM_SQDIFF_NORMED they gave different match scores, this is promising but still TM_CCORR_NORMED gave good matching score which is still unexpected from my side. I would be glad if someone can explain me the difference between the matching methods or give a link to already an existing page where these methods are being discussed, on opencv docs/tutorials there are only the formulas available but no detailed explanation. In the end I would like to know when to use which match method for what kind of image to get the best results.

Here is some more code:

    Mat img = Highgui.imread(inFile);
    Mat templ = Highgui.imread(templateFile);

    //  Create the result matrix
    int result_cols = img.cols() - templ.cols() + 1;
    int result_rows = img.rows() - templ.rows() + 1;
    Mat result = new Mat(result_rows, result_cols, CvType.CV_32FC1);

    //  Do the Matching 
    Imgproc.matchTemplate(img, templ, result, match_method);
    //  Localizing the best match with minMaxLoc
    MinMaxLocResult mmr = Core.minMaxLoc(result);

If I add normalization after the matching with

     Core.normalize(result, result, 0, 1, Core.NORM_MINMAX, -1, new Mat());

Then I become matchscore 0.0, which satisfies me and what I would expect, but this way gives only 1 or 0 nothing else in between, I would accept this if it was always giving correct results but sometimes it gives 0.0 for very good matches as well, i.e. when I cut a part from an image and try to find the cut part in the original image, then it gives 0.0, which should be the case... Also having values like 0.8734543, 0.234356, 0.450985948, helps me a lot to understand and analyze the comparisons, I have threshold of 0.9, any value above 0.9 I accept as correct, found.

Hi there, I dont always have square/rectangle images, sometimes I should match round images as well. Below are 2 images for example. Ball is the template image and the second is Source where the template should be searched. I can make the background of template transparent, but this gives error, making it white decreases the match score, because as you see on the Source image there is no white around the ball. These are just 2 examples pictures. Do you have suggestions solutions?

@berak do you have any suggestions for the png problem? Or maybe the problem is not png something else... but works when the source is jpg in DB and works when the source is png/jpg at local computer!

@berak Sorry wrote the @ wrongly and cant edit the comment now :S

OpenCV Error: Assertion failed ((img.depth() == CV_8U || img.depth() == CV_32F) && img.type() == templ.type()) in cv::matchTemplate, file ........\opencv\modules\imgproc\src\templmatch.cpp, line 249 Exception in thread "main" CvException [org.opencv.core.CvException: cv::Exception: ........\opencv\modules\imgproc\src\templmatch.cpp:249: error: (-215) (img.depth() == CV_8U || img.depth() == CV_32F) && img.type() == templ.type() in function cv::matchTemplate ] at org.opencv.imgproc.Imgproc.matchTemplate_0(Native Method) at org.opencv.imgproc.Imgproc.matchTemplate(Imgproc.java:7621) at MatchingDemo.run(MatchingDemo.java:104) On line 104 : Imgproc.matchTemplate(img, templ, result, match_method); I would be glad if you can help.

@AlexanderPacha Today I realized it wasnt fully working. When the inFile(Source) is a jpg on Mysql Database it works but when it is a png on Database I get the error below (Not enough space). PS: On my local computer both jpg and png work :( without the inputStream stuff.

OpenCV Error: Assertion failed ((img.depth() == CV_8U || img.depth() == CV_32F) && img.type() == templ.type()) in cv::matchTemplate, file ........\opencv\modules\imgproc\src\templmatch.cpp, line 249 Exception in thread "main" CvException [org.opencv.core.CvException: cv::Exception: ........\opencv\modules\imgproc\src\templmatch.cpp:249: error: (-215) (img.depth() == CV_8U || img.depth() == CV_32F) && img.type() == templ.type() in function cv::matchTemplate ] at org.opencv.imgproc.Imgproc.matchTemplate_0(Native Method) at org.opencv.imgproc.Imgproc.matchTemplate(Imgproc.java:7621) at MatchingDemo.run(MatchingDemo.java:104) On line 104 : Imgproc.matchTemplate(img, templ, result, match_method);

@break Im sorry if you got disappointed but in Stackoverflow when you copy someone else's answer and then post it as yours, you get a BIG "boO", I wouldnt like to take credits for what someone else did. What I did was just copy paste his code and then it worked, I haven't fixed or modified it. Today I realized it wasnt fully working. When the inFile(Source) is a jpg on Database it works but when it is a png on Database I get the error below (Not enough space). PS: On my local computer both jpg and png work :( without the inputStream stuff.

I found the answer here kudos to this guy, he is my hero :) Works perfectly, if you want the images in original color and not in grayscale you should change Highgui.IMREAD_GRAYSCALE with Highgui.IMREAD_UNCHANGED for more info check

@berak Okay I will in 23 hours :) thanks a lot for your efforts!

You are my hero, I was looking for this for 2 days...

@berak I found the answer, we were close : http://answers.opencv.org/question/31855/java-api-loading-image-from-any-java-inputstream/ works perfect

@berak this is the new error I got,

libpng error: PNG input buffer is incomplete OpenCV Error: Assertion failed (corrsize.height <= img.rows + templ.rows - 1 && corrsize.width <= img.cols + templ.cols - 1) in cv::crossCorr, file ........\opencv\modules\imgproc\src\templmatch.cpp, line 70 Exception in thread "main" CvException [org.opencv.core.CvException: cv::Exception: ........\opencv\modules\imgproc\src\templmatch.cpp:70: error: (-215) corrsize.height <= img.rows + templ.rows - 1 && corrsize.width <= img.cols + templ.cols - 1 in function cv::crossCorr ] at org.opencv.imgproc.Imgproc.matchTemplate_0(Native Method) at org.opencv.imgproc.Imgproc.matchTemplate(Imgproc.java:7621) at MatchingDemo.run(MatchingDemo.java:74) Line 74: Imgproc.matchTemplate(img, templ, reslt, matchmetod);

@break what is numBytesRead ? where do I get it?