Tukukkk

I'm writing a simple tool, the user can select an image and it should list all the colors found in the picture.

Now, I'm facing 2 main issues, one is that it's slow because I'm looping through all the pixels in an image.
Second, I'm getting unexpected results.

First thing's first, the code:

    public static async Task<List<ImageColor>> GetImageColorsAsync(StorageFile image)

    {

        List<ImageColor> colors = new List<ImageColor>();



        var imagestream = await image.OpenStreamForReadAsync(); // Convert image to stream

        var imageDecoder = await BitmapDecoder.CreateAsync(imagestream.AsRandomAccessStream()); // decode stream

        var imagePixelData = await imageDecoder.GetPixelDataAsync(); // get information about pixels

        var bytes = imagePixelData.DetachPixelData(); // get pixel data



        for (int x = 0; x < imageDecoder.PixelWidth; x++)

        {

            for (int y = 0; y < imageDecoder.PixelHeight; y++)

            {

                var location = (y * (int)imageDecoder.PixelWidth + x) * 3; // Navigate to corresponding coordinates

                var color = Color.FromArgb(0, bytes[location + 0], bytes[location + 1], bytes[location + 2]); // Filter Red Green Blue and convert this to Argb



                // find if color already exsists from its hex code

                string hex = color.ToString();

                var prevColor = colors.FirstOrDefault(a => a.ColorCodeHex == hex);



                if (colors.Count == 0 || prevColor == null)

                {

                    // new color

                    ImageColor imgColor = new ImageColor()

                    {

                        R = color.R,

                        G = color.G,

                        B = color.B,

                        ColorCodeHex = hex,

                        Occurence = 1

                    };



                    colors.Add(imgColor);

                }

                else

                {

                    // exsisting color

                    prevColor.Occurence++;

                }

            }

        }





        return colors;

    }

Now, do I really need to go through every single pixel?

And, what I did was test this function using a black image (completely black) and what I got was that there are 4 colors in that picture: black, red, green and blue.

Now the lines where I find the location and color are not mine, I found them online and I can't really verify that this is how you should do it.

Any help guys?