How to replace a pixel of a specified color with another color

[wf-soft]

I don't seem to have found an API to replace colors

[JimBobSquarePants]

Here's two ways to do it. Available on Image<TPixel> and individual frames.

For a given pixel at position x, y

// Image = Image<TPixel>
image[x, y] = ...

For operating on multiple pixels on the same row.

// Image = Image<TPixel>
Span<TPixel> row = image.GetPixelRowSpan(y);
row[x] = ...

[smhoff]

This would be great, except, where can I find GetPixeRowSpan?

[JimBobSquarePants]

That’s V1. See the docs for updated samples. https://docs.sixlabors.com/articles/imagesharp/pixelbuffers.html

[wf-soft]

@JimBobSquarePants I use the following method, but it doesn't seem to work, while mutate works normally.

var replace = new Rgba32(250, 250, 250);
            List<Rgba32> colors = new List<Rgba32>();
            colors.AddRange(Enumerable.Range(150, 105).Select(x => new Rgba32(x, x, x)));
            for (var y = 0; y < ImgFile1.ImgEditVM.image.Height; y++)
            {
                var row = ImgFile1.ImgEditVM.image.GetPixelRowSpan(y);
                for (var x = 0; x < ImgFile1.ImgEditVM.image.Width; x++)
                {
                    foreach (var color in colors)
                    {
                        if (row[x] == color) row[x] = replace;
                    }
                }
            }
//ImgFile1.ImgEditVM.image.Mutate(x => x.BinaryThreshold(1));
ImgFile1.ImgEditVM.SaveChang();

[wf-soft]

Am I missing any steps

[antonfirsov]

If I understand your code correctly, I assume there are not so many (r,g,b) == (x,x,x) (grayscale) pixels in your image, these are the only colors your code will replace.

Troubleshooting tip:
For making sure you can actually manipulate pixels from your code, I would first try to do something very simple, for example replacing every second row. Then move on implementing your algorithm.

[wf-soft]

It seems to work. Thank you for your help