Bitmap Color Replacement

Replace specific bitmap pixels color with specific intensity(0~100%) and/or limited alpha  into new defined color. First get bitmap pixels by width and height by an iteration then do process of pixel color replacement.

List of functions
○ Replace Color.
○ Replace Non Transparent Color.
○ Replace Non Transparent ColorA.
○ Set Replace All Color Bitmap (2 overloads).
○ Set Replace Color Bitmap(2 overloads).

Class Lerp is needed and can be viewed here

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Source Code

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using System; using System.Collections; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace TechScales { internal static class BitmapExtensions { /// <summary> /// Replace color with limited alpha and specific intensity /// </summary> /// <param name="source"></param> /// <param name="to"></param> /// <param name="minAlphaReplace"></param> /// <param name="intensity"></param> /// <returns></returns> internal static Bitmap SetReplaceAllColorBitmap( this Bitmap source, Color to, byte minAlphaReplace = 0, float intensity = .25f) { if (source == null) { return null; } if (intensity < 0.1f && intensity > 1f) { intensity = 1f; } Bitmap bm = new Bitmap(source); for (int w = 0; w < source.Width - 1; w++) { for (int h = 0; h < source.Height - 1; h++) { Color c = bm.GetPixel(w, h); if (c.A > minAlphaReplace) { c = Color.FromArgb(c.A, intensity == 1f ? to : c.Lerp(to, intensity)); bm.SetPixel(w, h, c); } } } return bm; } /// <summary> /// Replace color with specific intensity /// </summary> /// <param name="source"></param> /// <param name="to"></param> /// <param name="minAlphaReplace"></param> /// <param name="intensity"></param> /// <returns></returns> internal static Bitmap SetReplaceAllColorBitmap( this Bitmap source, Color to, float intensity) { return SetReplaceAllColorBitmap(source, to, 0, intensity); } /// <summary> /// Replace all color into new color with specific intensity /// </summary> /// <param name="source">gambar</param> /// <param name="col">warna baru</param> /// <param name="intensity"></param> /// <returns></returns> internal static Bitmap SetReplaceColorBitmap( this Bitmap source, Color col, float intensity = 1f) { if (source == null) { return null; } if (intensity < 0.1f && intensity > 1f) { intensity = 1f; } Bitmap bm = new Bitmap(source); for (int w = 0; w < source.Width - 1; w++) { for (int h = 0; h < source.Height - 1; h++) { Color c = bm.GetPixel(w, h); if (c.A > 0) { c = Color.FromArgb(c.A, intensity == 1f ? col : c.Lerp(col, intensity)); bm.SetPixel(w, h, c); } } } return bm; } /// <summary> /// Replace specific color into new color with specific intensity /// </summary> /// <param name="source">gambar</param> /// <param name="from">warna diganti</param> /// <param name="to">watrna pengganti</param> /// <param name="intensity">intensitas</param> /// <returns></returns> internal static Bitmap SetReplaceColorBitmap( this Bitmap source, Color @from, Color to, float intensity = 1f) { if (source == null) { return null; } if (from.Equals(to)) { return source; } if (intensity < 0.1f && intensity > 1f) { intensity = 1f; } Bitmap bm = new Bitmap(source); for (int w = 0; w < source.Width - 1; w++) { for (int h = 0; h < source.Height - 1; h++) { Color c = bm.GetPixel(w, h); if (c.R == from.R && c.G == from.B && c.B == from.B) { c = Color.FromArgb(c.A, intensity == 1f ? to : c.Lerp(to, intensity)); bm.SetPixel(w, h, c); } } } return bm; } private static unsafe Bitmap ReplaceNonTransparentColorA( Bitmap source, Color replacement, byte alphaLimitMinim = 5) { const int PIXEL_SIZE = 4; // 32 bits per pixel var target = new Bitmap(source.Width, source.Height, PixelFormat.Format32bppArgb); BitmapData sourceData = null, targetData = null; try { sourceData = source.LockBits( new Rectangle(0, 0, source.Width, source.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); targetData = target.LockBits( new Rectangle(0, 0, target.Width, target.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb); for (int y = 0; y < source.Height; ++y) { byte* sourceRow = (byte*)sourceData.Scan0 + (y * sourceData.Stride); byte* targetRow = (byte*)targetData.Scan0 + (y * targetData.Stride); for (int x = 0; x < source.Width; ++x) { byte b = sourceRow[x * PIXEL_SIZE + 0]; byte g = sourceRow[x * PIXEL_SIZE + 1]; byte r = sourceRow[x * PIXEL_SIZE + 2]; byte a = sourceRow[x * PIXEL_SIZE + 3]; r = replacement.R; g = replacement.G; b = replacement.B; targetRow[x * PIXEL_SIZE + 0] = b; targetRow[x * PIXEL_SIZE + 1] = g; targetRow[x * PIXEL_SIZE + 2] = r; targetRow[x * PIXEL_SIZE + 3] = a; } } } finally { if (sourceData != null) { source.UnlockBits(sourceData); } if (targetData != null) { target.UnlockBits(targetData); } } return target; } internal static Bitmap ReplaceNonTransparentColor(this Bitmap source, Color replacement, byte alphaLimitMinim = 5) { return ReplaceNonTransparentColorA(source, replacement, alphaLimitMinim); } internal static Bitmap ReplaceColor( this Bitmap source, Color @from, Color to, float intensity = 1f) { return SetReplaceColorBitmap(source, from, to, intensity); } } }

Test
Result
1. 2. 3. 4. 5. 6.
Code
1. Bitmap bm = original bitmap
2. bm.ReplaceColor(Color.Black, Color.DodgerBlue, 0.85f); 3. bm.ReplaceNonTransparentColor(Color.Green, 5); 4. bm.SetReplaceAllColorBitmap(Color.DodgerBlue, 0, 0.25f); 5. bm.SetReplaceAllColorBitmap(Color.Yellow, 0.65f); 6. bm.SetReplaceAllColorBitmap(Color.Black, Color.Red, 0.85f);

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RGB Color Linear Interpolation

Sometimes some cases, color (C0) with its RGB values, need to be changed to a new color (Cn), based from another color (C1) with a certain amount of percentage (0 to 100%) from C1, linearly.

(C0 » C1 (n%) = Cn)

The process of converting color, from one color that influenced by another color into a new color, we name it 'Color Linear Interpolation (Lerp)'

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Source Code

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using System; using System.Collections; using System.Collections.Generic; using System.Diagnostics; using System.Drawing; namespace TechScales { static class ColorExtension { internal static float Lerp(this float start, float end, float amount) { float difference = end - start; float adjusted = difference * amount; return (start + adjusted); } /// <summary> /// linear interpolation /// </summary> /// <param name="colour"></param> /// <param name="to" >Color To</param> /// <param name="amount">0 ~ 1.0</param> /// <returns></returns> /// <remarks></remarks> internal static Color Lerp(this Color colour, Color to, float amount) { // start color float r0 = (float)colour.R, g0 = (float)colour.G, b0 = (float)colour.B; // end color float r1 = (float)to.R, g1 = (float)to.G, b1 = (float)to.B; // lerp the color byte r = (byte)(r0.Lerp(r1, amount)), g = (byte)(g0.Lerp(g1, amount)), b = (byte)(b0.Lerp(b1, amount)); // return the new color return Color.FromArgb(r, g, b); } internal static T DeepClone<T>(this T a) { using (var stream = new System.IO.MemoryStream()) { var formatter = new System.Runtime.Serialization .Formatters.Binary.BinaryFormatter(); formatter.Serialize(stream, a); stream.Position = 0; return (T)formatter.Deserialize(stream); } } /// <summary> /// simple inversion of color /// </summary> /// <param name="from"></param> /// <returns></returns> private static Color InvertA(this Color from) { return Color.FromArgb(from.A, 255 - from.R, 255 - from.G, 255 - from.B); } /// <summary> /// simple inversion of color, to black or white /// </summary> /// <param name="from"></param> /// <param name="toBlackOrWhiteColor"></param> /// <returns></returns> internal static Color Invert(this Color from, bool toBlackOrWhiteColor = true) { if (!toBlackOrWhiteColor) { return from.InvertA(); } return (GetBrightness(from) > 130 ? Color.Black : Color.White); } private static int GetBrightness(Color c) { return (int)Math.Sqrt(c.R * c.R * .299 + c.G * c.G * .587 + c.B * c.B * .114); } /* * another way */ static Color LerpRGB(Color a, Color b, float t) { return Color.FromArgb ( a.A + (int)((b.A - a.A) * t), a.R + (int)((b.R - a.R) * t), a.G + (int)((b.G - a.G) * t), a.B + (int)((b.B - a.B) * t) ); } } }

Test
Immediate Window
?System.Drawing.Color.Blue.Lerp(System.Drawing.Color.Red, 0.25f);
"{Name=ff3f00bf, ARGB=(255, 63, 0, 191)}" A: 255 B: 191 G: 0 IsEmpty: false IsKnownColor: false IsNamedColor: false IsSystemColor: false Name: "ff3f00bf" R: 63
?System.Drawing.Color.Blue.Lerp(System.Drawing.Color.Yellow, 0.25f);
"{Name=ff3f3fbf, ARGB=(255, 63, 63, 191)}" A: 255 B: 191 G: 63 IsEmpty: false IsKnownColor: false IsNamedColor: false IsSystemColor: false Name: "ff3f3fbf" R: 63
var newColor = Color.Blue.Lerp(Color.Cyan, 0.85f); "{Name=ff00d8ff, ARGB=(255, 0, 216, 255)}" A: 255 B: 255 G: 216 IsEmpty: false IsKnownColor: false IsNamedColor: false IsSystemColor: false Name: "ff00d8ff" R: 0

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