C#•2y ago

✅ Process image using Emgu.CV, WPF app .NET 7.0

So i have to check if the image i upload is in Grayscale or not and based on it make further progress here is how i upload image:

        private void BtnOpenNewFile_Click(object sender, RoutedEventArgs e)
        {
            var openFileDialog = new OpenFileDialog
            {
                Filter = "Image Files (*.bmp;*.jpg;*.jpeg;*.gif;*.png)|*.bmp;*.jpg;*.jpeg;*.gif;*.png"
            };
            
            if (openFileDialog.ShowDialog() == true)
            {
                Mat image = new Mat(openFileDialog.FileName, ImreadModes.Color);
                string fileName = Path.GetFileNameWithoutExtension(openFileDialog.FileName);

                ImageWindow imageWindow = new ImageWindow();

                if (image.Height > 1000 || image.Width > 1000)
                {
                    imageWindow.Height = 1000;
                    imageWindow.Width = 1000;
                }
                else
                {
                    imageWindow.Height = image.Height + 200;
                    imageWindow.Width = image.Width + 50;
                }

                imageWindow.Title = fileName;
                imageWindow.ImgMainImage.Source = image.ToBitmapSource();
                imageWindow.Show();
            }
        }

        private void BtnOpenNewFile_Click(object sender, RoutedEventArgs e)
        {
            var openFileDialog = new OpenFileDialog
            {
                Filter = "Image Files (*.bmp;*.jpg;*.jpeg;*.gif;*.png)|*.bmp;*.jpg;*.jpeg;*.gif;*.png"
            };
            
            if (openFileDialog.ShowDialog() == true)
            {
                Mat image = new Mat(openFileDialog.FileName, ImreadModes.Color);
                string fileName = Path.GetFileNameWithoutExtension(openFileDialog.FileName);

                ImageWindow imageWindow = new ImageWindow();

                if (image.Height > 1000 || image.Width > 1000)
                {
                    imageWindow.Height = 1000;
                    imageWindow.Width = 1000;
                }
                else
                {
                    imageWindow.Height = image.Height + 200;
                    imageWindow.Width = image.Width + 50;
                }

                imageWindow.Title = fileName;
                imageWindow.ImgMainImage.Source = image.ToBitmapSource();
                imageWindow.Show();
            }
        }

and here is how i try to convert it but no matter if i upload gray image or not it says the image is already in grayscale, (i checked using ImageJ)

9 Replies

WhiteboyOP•2y ago

        private void BtnConvert2Grey_Click(object sender, RoutedEventArgs e)
        {
            BitmapSource bitmapSource = (BitmapSource)ImgMainImage.Source;
            int width = bitmapSource.PixelWidth;
            int height = bitmapSource.PixelHeight;
            var grayImage = new Image<Gray, byte>(width, height);
            
            // Check if image is already grayscale
            if (grayImage.NumberOfChannels == 1)
            {
                MessageBox.Show("It's already in grayscale");
                return;
            }

            int stride = width * ((bitmapSource.Format.BitsPerPixel + 7) / 8);
            byte[] pixels = new byte[height * stride];
            bitmapSource.CopyPixels(pixels, stride, 0);

            // Convert bitmap to gray image
            grayImage.Bytes = pixels;

            // Convert to grayscale
            grayImage = grayImage.Convert<Gray, byte>();

            // Set converted image as source of ImgMainImage
            ImgMainImage.Source = grayImage.ToBitmapSource();

            MessageBox.Show("Image converted to grayscale");
        }

        private void BtnConvert2Grey_Click(object sender, RoutedEventArgs e)
        {
            BitmapSource bitmapSource = (BitmapSource)ImgMainImage.Source;
            int width = bitmapSource.PixelWidth;
            int height = bitmapSource.PixelHeight;
            var grayImage = new Image<Gray, byte>(width, height);
            
            // Check if image is already grayscale
            if (grayImage.NumberOfChannels == 1)
            {
                MessageBox.Show("It's already in grayscale");
                return;
            }

            int stride = width * ((bitmapSource.Format.BitsPerPixel + 7) / 8);
            byte[] pixels = new byte[height * stride];
            bitmapSource.CopyPixels(pixels, stride, 0);

            // Convert bitmap to gray image
            grayImage.Bytes = pixels;

            // Convert to grayscale
            grayImage = grayImage.Convert<Gray, byte>();

            // Set converted image as source of ImgMainImage
            ImgMainImage.Source = grayImage.ToBitmapSource();

            MessageBox.Show("Image converted to grayscale");
        }

Anton•2y ago

gray means the values in all color channels are equal you can just go through all pixels' colors and check if they're equal I'm not wrong, right?

WhiteboyOP•2y ago

@AntonC i can but it's slow as shit i hsould be able to use Emgu.CV lib to do it

Anton•2y ago

I don't know what that is

Anton•2y ago

I'd just spin up a few threads using this thing https://learn.microsoft.com/en-us/dotnet/standard/parallel-programming/how-to-write-a-simple-parallel-foreach-loop

Write a simple parallel program using Parallel.ForEach

In this article, learn how to enable data parallelism in .NET. Write a Parallel.ForEach loop over any IEnumerable or IEnumerable data source.

Anton•2y ago

if it's still ot fast enough, one could use simd, but I've never needed to use this https://learn.microsoft.com/en-us/dotnet/standard/simd

SIMD-accelerated types in .NET

This article describes SIMD-enable types in .NET and demonstrates how to use hardware SIMD operations in C# and .NET.

Anton•2y ago

But who knows, maybe that library supports this stuff in a simpler way

WhiteboyOP•2y ago

it does and it's mandatory i use it for this method but ty for trying to help but i think im doing wrong type of image by doing bitmapSource bacuse it's in system.drawing and i need to use type from emgu

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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✅ Process image using Emgu.CV, WPF app .NET 7.0