Chromis 1.0.3

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Chromis 🐟

Extract dominant colors from images using K-Means, Median Cut, or Octree algorithms.
Chromis is a lightweight, cross-platform .NET library for color extraction, designed with zero UI dependencies and clean data structures.

✨ Features

• 🎨 Extract dominant colors from images
• ⚡ Multiple algorithms:
  • K-Means
  • Median Cut
  • Octree
• 🧩 Cross-platform (.NET Framework / .NET 6+)
• 🪶 Lightweight and dependency-free public API
• 🔄 Compatible with legacy System.Drawing types (via overloads)

📦 Installation

dotnet add package Chromis

🧠 Basic Usage

C#

using System;
using System.Collections.Generic;
using System.Drawing;

public List<Color> GetPixelsFromImage(Image image, int stepCount = 5)
{
    if (stepCount < 1)
        throw new ArgumentOutOfRangeException(nameof(stepCount), "stepCount must greater than 1");
    var pixels = new List<Color>();
    using (var bmp = new Bitmap(image))
    {
        for (int x = 0; x < bmp.Width; x += stepCount)
        {
            for (int y = 0; y < bmp.Height; y += stepCount)
            {
                pixels.Add(bmp.GetPixel(x, y));
            }
        }
    }
    return pixels;
}

Usage

using Chromis;

var sampledColors = GetPixelsFromImage(pictureBoxMain.Image);
var rgbColors = new List<RGBColor>();
foreach (var color in sampledColors)
{
    rgbColors.Add(RGBColor.FromRGB(color.R, color.G, color.B));
}
var colorInfos = ColorExtractor.Extract(rgbColors, 10);
foreach (var ci in colorInfos)
{
    Console.WriteLine($"{ci.Color.R}, {ci.Color.G}, {ci.Color.B} - {ci.Ratio:P}");
}

VB.NET

Imports System;
Imports System.Collections.Generic;
Imports System.Drawing;

Public Function GetPixelsFromImage(image As Image, Optional stepCount As Integer = 5) As List(Of Color)
    If stepCount < 1 Then Throw New ArgumentOutOfRangeException(NameOf(stepCount), "stepCount must greater than 1")
    Dim pixels As New List(Of Color)()
    Using bmp = New Bitmap(image)
        For x = 0 To bmp.Width - 1 Step stepCount
            For y = 0 To bmp.Height - 1 Step stepCount
                pixels.Add(bmp.GetPixel(x, y))
            Next
        Next
    End Using
    Return pixels
End Function

Usage

Imports Chromis

Dim pixels As New List(Of ColorExtractor.RGBColor)
For Each sampledColor In GetPixelsFromImage(PictureBoxMain.Image)
    pixels.Add(ColorExtractor.RGBColor.FromRGB(sampledColor.R, sampledColor.G, sampledColor.B))
Next
Dim colorInfos = ColorExtractor.Extract(pixels, 10)
For Each ci In colorInfos
    Console.WriteLine($"{ci.Color.R}, {ci.Color.G}, {ci.Color.B} - {ci.Ratio:P}")
Next

• R, G, B: RGB color values
• Ratio: Percentage of this color in the image (0 ~ 1)

📊 Algorithms

Chromis supports multiple color quantization algorithms:

• K-Means – balanced and accurate
• Median Cut – fast and classic
• Octree – memory efficient

📄 License

Apache-2.0 License