question ColorMomentHash

[kerwinxu]

Summary of your issue

public override void Compute( InputArray inputArr, OutputArray outputArr ) outputArr Type: OpenCvSharp.OutputArray 42 hash values with type CV_64F(double) Excuse me ， the bytes of size is (42 * 64 = 2688 ) bytes ? but :

 Mat mat = new Mat(@"2022-06-19-10-09-8176.jpg");
 Mat mat2 = new Mat();
 var hashfun = ColorMomentHash.Create();
 hashfun.Compute(mat, mat2);
 byte[] bs = mat2.ToBytes();
 Console.WriteLine("字节长度:" + bs.Length.ToString());

result = 69 bytes , why ?

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[shimat]

The test code below may help you. https://github.com/shimat/opencvsharp/blob/master/test/OpenCvSharp.Tests/img_hash/ColorMomentHashTest.cs

using Mat mat = new Mat(@"2022-06-19-10-09-8176.jpg");
using Mat mat2 = new Mat();
using var hashfun = ColorMomentHash.Create();
hashfun.Compute(mat, mat2);

mat2.GetArray(out double[] hashValues);
Console.WriteLine(hashValues.Length); // 42

[kerwinxu]

win7 , net 3.5, OpenCvSharp3-AnyCPU I found the following , var hash = new Mat<double>() but in my code , an error was generated ， I write the following, var hash = new Mat(new Size(1,42), MatType.CV_64FC1)

The Rows is ok . The Cols is ok . but the data is not ok , I don't have the ToArraymethod here. I use the following method . hash.ToBytes() hash.ToMemoryStream().ToArray() but the number of byte is 69

I try win10,net4.6.1,opencvsharp4.windows

` static void Main(string[] args) { using (var model = ColorMomentHash.Create()) using (var img = new Mat(@"2022-06-19-10-09-8176.jpg")) using (var hash = new Mat(new Size(1, 42), MatType.CV_64FC1)) {

            model.Compute(img, hash);
            var bs = hash.ToBytes();
            Console.WriteLine("number of byte" + bs.Length);

        }
    }

`

the tesult is 69

[shimat]

You should not use ToBytes, since ToBytes is an alias for ImEncode, which returns the PNG-encoded result of its Mat data.

[kerwinxu]

You should not use ToBytes, since ToBytes is an alias for ImEncode, which returns the PNG-encoded result of its Mat data.

Thank you . i use the following . double[] dbl = new double[42]; hash.GetArray(0, 0, dbl);

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