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C# setHue (or alternatively, convert HSL to RGB and set RGB)

C# has a very convenient getHue method, but I can't find a setHue method. Is there one?
If not, I think the best way to define a color after changing the hue would be to convert the HSL value to RGB, and then set the RGB value. I know there are formulas on the internet for doing this, but how would I best go about performing this conversion from HSL to RGB using C#?
Thank You

To set the Hue you create a new Color, maybe from a given one by using GetHue and GetSaturation. See below for the getBrightness function!
I'm using this:
Color SetHue(Color oldColor)
{
var temp = new HSV();
temp.h = oldColor.GetHue();
temp.s = oldColor.GetSaturation();
temp.v = getBrightness(oldColor);
return ColorFromHSL(temp);
}
// A common triple float struct for both HSL & HSV
// Actually this should be immutable and have a nice constructor!!
public struct HSV { public float h; public float s; public float v;}
// the Color Converter
static public Color ColorFromHSL(HSV hsl)
{
if (hsl.s == 0)
{ int L = (int)hsl.v; return Color.FromArgb(255, L, L, L); }
double min, max, h;
h = hsl.h / 360d;
max = hsl.v < 0.5d ? hsl.v * (1 + hsl.s) : (hsl.v + hsl.s) - (hsl.v * hsl.s);
min = (hsl.v * 2d) - max;
Color c = Color.FromArgb(255, (int)(255 * RGBChannelFromHue(min, max,h + 1 / 3d)),
(int)(255 * RGBChannelFromHue(min, max,h)),
(int)(255 * RGBChannelFromHue(min, max,h - 1 / 3d)));
return c;
}
static double RGBChannelFromHue(double m1, double m2, double h)
{
h = (h + 1d) % 1d;
if (h < 0) h += 1;
if (h * 6 < 1) return m1 + (m2 - m1) * 6 * h;
else if (h * 2 < 1) return m2;
else if (h * 3 < 2) return m1 + (m2 - m1) * 6 * (2d / 3d - h);
else return m1;
}
Do not use the built-in GetBrightness method! It returns the same value (0.5f) for red, magenta, cyan, blue and yellow (!). This is better:
// color brightness as perceived:
float getBrightness(Color c)
{ return (c.R * 0.299f + c.G * 0.587f + c.B *0.114f) / 256f; }

System.Drawing.Color is a value type, which are almost always made immutable, especially in frameworks. That's why you can't setHue on it, you can only construct a new value type with fields you need.
So, if you have a function that will give you RGB values for your HSB values, you can do it like this
Color oldColor = ...;
int red, green, blue;
FromHSB(oldColor.GetHue(), oldColor.GetSaturation(), oldColor.GetBrightness(), out red, out green out blue);
Color newColor = Color.FromArgb(oldColor.A, red, green, blue);
where FromHSB looks like this
void FromHSB(float hue, float saturation, float brightness, out int red, out int green, out int blue)
{
// ...
}

Image hue modification in C#

I have an image and i want to modify the hue of that particular image to specific value.
I know rgb to hsl and hsl to rgb conversion mathematical formula but I am not being able to implement this thing into c#.
Following is the pseudo:
for(x=0;x<image_width;x++)
{
for(y=0;y<image_height;y++)
{
Color oldColor=GetColorFromPixel(x,y);
Color newColor=ModifyHue(oldColor);
SetColorPixel(x,y,newColor);
}
}
Thanks

Due to the fact, that the Color structure already has a GetHue(), GetSaturation() and GetBrightness() it would be nice to also construct a color from these values. So i found the following code somewhere on the net a while ago (currently can't find it again, but it was from a Microsoft guy blog and he also had a test that steps through all KnownColor).
/// <summary>
/// Creates a Color from alpha, hue, saturation and brightness.
/// </summary>
/// <param name="alpha">The alpha channel value.</param>
/// <param name="hue">The hue value.</param>
/// <param name="saturation">The saturation value.</param>
/// <param name="brightness">The brightness value.</param>
/// <returns>A Color with the given values.</returns>
public static Color FromAhsb(int alpha, float hue, float saturation, float brightness)
{
if (0 > alpha || 255 < alpha)
{
throw new ArgumentOutOfRangeException("alpha", alpha,
"Value must be within a range of 0 - 255.");
}
if (0f > hue || 360f < hue)
{
throw new ArgumentOutOfRangeException("hue", hue,
"Value must be within a range of 0 - 360.");
}
if (0f > saturation || 1f < saturation)
{
throw new ArgumentOutOfRangeException("saturation", saturation,
"Value must be within a range of 0 - 1.");
}
if (0f > brightness || 1f < brightness)
{
throw new ArgumentOutOfRangeException("brightness", brightness,
"Value must be within a range of 0 - 1.");
}
if (0 == saturation)
{
return Color.FromArgb(alpha, Convert.ToInt32(brightness * 255),
Convert.ToInt32(brightness * 255), Convert.ToInt32(brightness * 255));
}
float fMax, fMid, fMin;
int iSextant, iMax, iMid, iMin;
if (0.5 < brightness)
{
fMax = brightness - (brightness * saturation) + saturation;
fMin = brightness + (brightness * saturation) - saturation;
}
else
{
fMax = brightness + (brightness * saturation);
fMin = brightness - (brightness * saturation);
}
iSextant = (int)Math.Floor(hue / 60f);
if (300f <= hue)
{
hue -= 360f;
}
hue /= 60f;
hue -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);
if (0 == iSextant % 2)
{
fMid = hue * (fMax - fMin) + fMin;
}
else
{
fMid = fMin - hue * (fMax - fMin);
}
iMax = Convert.ToInt32(fMax * 255);
iMid = Convert.ToInt32(fMid * 255);
iMin = Convert.ToInt32(fMin * 255);
switch (iSextant)
{
case 1:
return Color.FromArgb(alpha, iMid, iMax, iMin);
case 2:
return Color.FromArgb(alpha, iMin, iMax, iMid);
case 3:
return Color.FromArgb(alpha, iMin, iMid, iMax);
case 4:
return Color.FromArgb(alpha, iMid, iMin, iMax);
case 5:
return Color.FromArgb(alpha, iMax, iMin, iMid);
default:
return Color.FromArgb(alpha, iMax, iMid, iMin);
}
}
With this function you are able to work within the HSB (or HSV) color presentation not within the HSL presentation. For further informations about their differences take a look at this wikipedia article.

If you just want to try out or performance is not critical, the easist way is to use the Bitmap.GetPixel and Bitmap.SetPixel methods:
var bm = new Bitmap(filename);
for(int x=0;x<bm.Width;x++)
{
for(y=0;y<bm.Height;y++)
{
Color oldColor=bm.GetPixel(x,y);
Color newColor=ModifyHue(oldColor);
bm.SetPixel(x,y,newColor);
}
}
If you want more performant operation, you should look at the Bitmap.LockBits method which fixes the entire bitmap on a memory location and lets you modify this memory directly.

"Colourizing" a Bitmap in .NET

If you have a System.Drawing.Bitmap instance that contains a greyscale image, is there a built in way to "colourize" it with the influence of another colour?
For example, if you had a black and white (greyscale) picture of a coffee mug and you wanted to create separate images of red, green and purple versions programmatically.

I don't have a code example to give but here's a way to do this. Convert each pixel from RGB to HSV and change the Hue and Saturation component on each pixel. The Hue controls the Color. The Value should stay the same. The result will be a Bitmap with the same lightness and darkness but with a different color.
Edit: here's an example. Notice the Hue and Saturation update.
public static Color ColorFromAhsb(int a, float h, float s, float b)
{
if (0 > a || 255 < a)
{
throw new Exception("a");
}
if (0f > h || 360f < h)
{
throw new Exception("h");
}
if (0f > s || 1f < s)
{
throw new Exception("s");
}
if (0f > b || 1f < b)
{
throw new Exception("b");
}
if (0 == s)
{
return Color.FromArgb(a, Convert.ToInt32(b * 255),
Convert.ToInt32(b * 255), Convert.ToInt32(b * 255));
}
float fMax, fMid, fMin;
int iSextant, iMax, iMid, iMin;
if (0.5 < b)
{
fMax = b - (b * s) + s;
fMin = b + (b * s) - s;
}
else
{
fMax = b + (b * s);
fMin = b - (b * s);
}
iSextant = (int)Math.Floor(h / 60f);
if (300f <= h)
{
h -= 360f;
}
h /= 60f;
h -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);
if (0 == iSextant % 2)
{
fMid = h * (fMax - fMin) + fMin;
}
else
{
fMid = fMin - h * (fMax - fMin);
}
iMax = Convert.ToInt32(fMax * 255);
iMid = Convert.ToInt32(fMid * 255);
iMin = Convert.ToInt32(fMin * 255);
switch (iSextant)
{
case 1:
return Color.FromArgb(a, iMid, iMax, iMin);
case 2:
return Color.FromArgb(a, iMin, iMax, iMid);
case 3:
return Color.FromArgb(a, iMin, iMid, iMax);
case 4:
return Color.FromArgb(a, iMid, iMin, iMax);
case 5:
return Color.FromArgb(a, iMax, iMin, iMid);
default:
return Color.FromArgb(a, iMax, iMid, iMin);
}
}
private void Form1_Load(object sender, EventArgs e)
{
var bmp = new Bitmap("c:\\bw.bmp");
foreach (int y in Enumerable.Range(0, bmp.Height))
{
foreach (int x in Enumerable.Range(0,bmp.Width))
{
var p = bmp.GetPixel(x, y);
var h = p.GetHue();
var c = ColorFromAhsb(p.A, p.GetHue() + 200, p.GetSaturation() + 0.5f, p.GetBrightness());
bmp.SetPixel(x, y, c);
}
}
pictureBox1.Image = bmp;
//bmp.Dispose();
}

If it's an 8 bit image, you can just use a different the palette (Image.Palette). That's essentially a lookup table that assigns a Color value to each possible pixel byte value. Much faster than changing all pixels in a loop.

See here
I have used this in the past. You are wanting to look specifically at ToSepia.
You may need to deconstruct this a bit but it has worked for me.

I'd create a copy of the original image and them put a separate semi transparent image of the desired color of the top.
Update: see example at http://www.codeproject.com/KB/cs/Merge_Images_in_C_.aspx

I am unsure of a built in way but, if you represent each colour as a float rather than a byte (255 becomes 1 - full intensity), multiplying the each channel with your desired colour should give the effect you are talking about.
(1,1,1) "white" * (1,0,0) "red" = (1,0,0) "red"
(0.5,0.5, 0.5) "grey" * (0,1,0) "green" = (0,0.5,0) "dark green"
You do need to apply this per pixel though.

C#: Create a lighter/darker color based on a system color [duplicate]

This question already has answers here:
How do I adjust the brightness of a color?
(7 answers)
Closed 1 year ago.
Duplicate
How do I adjust the brightness of a color?
How do I determine darker or lighter color variant of a given color?
Programmatically Lighten a Color
Say I have
var c = Color.Red;
Now I want to create a new Color that is lighter or darker than that color. How can I do that without too much hassle?

ControlPaint.Light .Dark .DarkDark, etc.
Color lightRed = ControlPaint.Light( Color.Red );

I recently blogged about this. The main idea is to apply a given correction factor to each of the color components. The following static method modifies the brightness of a given color with a specified correction factor and produces a darker or a lighter variant of that color:
/// <summary>
/// Creates color with corrected brightness.
/// </summary>
/// <param name="color">Color to correct.</param>
/// <param name="correctionFactor">The brightness correction factor. Must be between -1 and 1.
/// Negative values produce darker colors.</param>
/// <returns>
/// Corrected <see cref="Color"/> structure.
/// </returns>
public static Color ChangeColorBrightness(Color color, float correctionFactor)
{
float red = (float)color.R;
float green = (float)color.G;
float blue = (float)color.B;
if (correctionFactor < 0)
{
correctionFactor = 1 + correctionFactor;
red *= correctionFactor;
green *= correctionFactor;
blue *= correctionFactor;
}
else
{
red = (255 - red) * correctionFactor + red;
green = (255 - green) * correctionFactor + green;
blue = (255 - blue) * correctionFactor + blue;
}
return Color.FromArgb(color.A, (int)red, (int)green, (int)blue);
}

You can also do this using a Lerp function. There's one in XNA, but it's easy to write yourself.
See my answer to this similar question for a C# implementation.
The function lets you do this:
// make red 50% lighter:
Color.Red.Lerp( Color.White, 0.5 );
// make red 75% darker:
Color.Red.Lerp( Color.Black, 0.75 );
// make white 10% bluer:
Color.White.Lerp( Color.Blue, 0.1 );

Most of these methods do darken the color but they adjust the hue way to much so the result doesn't look very good. The best answer is to use Rich Newman's HSLColor class and adjust the luminosity.
public Color Darken(Color color, double darkenAmount) {
HSLColor hslColor = new HSLColor(color);
hslColor.Luminosity *= darkenAmount; // 0 to 1
return hslColor;
}

Taking the core method of #Pavel's answer I prepared the following two little extension methods for a more intuitive (at least for me) signature.
public static Color LightenBy(this Color color, int percent)
{
return ChangeColorBrightness(color, percent/100.0);
}
public static Color DarkenBy(this Color color, int percent)
{
return ChangeColorBrightness(color, -1 * percent / 100.0);
}

Here's some javascript code I use for lightening/darkening a given colour. You could use it as a base for an equivalent C# function
It works by calculating a distance from pure white of each of the RGB components and then adjusts this distance by the provided factor. The new distance is used to calculate the new colour. A factor of between 0 and 1 darkens, a factor higher than 1 lightens
function Darken( hexColor, factor )
{
if ( factor < 0 ) factor = 0;
var c = hexColor;
if ( c.substr(0,1) == "#" )
{
c = c.substring(1);
}
if ( c.length == 3 || c.length == 6 )
{
var i = c.length / 3;
var f; // the relative distance from white
var r = parseInt( c.substr(0, i ), 16 );
f = ( factor * r / (256-r) );
r = Math.floor((256 * f) / (f+1));
r = r.toString(16);
if ( r.length == 1 ) r = "0" + r;
var g = parseInt( c.substr(i, i), 16);
f = ( factor * g / (256-g) );
g = Math.floor((256 * f) / (f+1));
g = g.toString(16);
if ( g.length == 1 ) g = "0" + g;
var b = parseInt( c.substr( 2*i, i),16 );
f = ( factor * b / (256-b) );
b = Math.floor((256 * f) / (f+1));
b = b.toString(16);
if ( b.length == 1 ) b = "0" + b;
c = r+g+b;
}
return "#" + c;
}

You can also simply work on the RGB percentage to get it lighter or darker as you want, Here is an example for how to make a color darker x% than it is:
//_correctionfactory in percentage, e.g 50 = make it darker 50%
private Color DarkerColor(Color color, float correctionfactory = 50f)
{
const float hundredpercent = 100f;
return Color.FromArgb((int)(((float)color.R / hundredpercent) * correctionfactory),
(int)(((float)color.G / hundredpercent) * correctionfactory), (int)(((float)color.B / hundredpercent) * correctionfactory));
}
One more thing we can also reverse the process to be lighter instead, Only we getting the result of 255 - RGB and then multiply it by the percentage we want like the following example:
private Color LighterColor(Color color, float correctionfactory = 50f)
{
correctionfactory = correctionfactory / 100f;
const float rgb255 = 255f;
return Color.FromArgb((int)((float)color.R + ((rgb255 - (float)color.R) * correctionfactory)), (int)((float)color.G + ((rgb255 - (float)color.G) * correctionfactory)), (int)((float)color.B + ((rgb255 - (float)color.B) * correctionfactory))
);
}
Hope that helps.

I made a site that does this colorglower.com You can check it out to see a demo.
Here's the javascript code i used.
function lighten(color) {
// convert to decimal and change luminosity
var luminosity = 0.01
var computedColors = new Array();
var newColor = "#",
c, i, n, black = 0,
white = 255;
for (n = 0; n < 10; n++) {
for (i = 0; i < 3; i++) {
c = parseInt(color.substr(i * 2, 2), 16);
c = Math.round(Math.min(Math.max(black, c + (luminosity * white)), white)).toString(16);
newColor += ("00" + c).substr(c.length);
}
computedColors[n] = newColor;
var arrayUnique = checkIfArrayIsUnique(computedColors);
if (arrayUnique == false) {
computedColors.pop();
break;
}
computedColors[n] = newColor;
newColor = "#";
luminosity += calcPercentage();
}
return computedColors;
}
What this code does is it receives a hex color and then it outputs 10 lightest color versions of it and puts in in the array. You can change the luminosity to whatever you like to adjust the shade percentage. To darken the colors you just need to change:
luminosity -= calcPercentage();

Using HSI converter library(search google). And then, adjust I channel for lighter/darker color.

I changed Pavel Vladov function to modify even RGB component, to get shades on any combination of R/G/B directions:
Public Function ChangeColorShades(color As Color, correctionFactor As Single, bR As Boolean, bG As Boolean, bB As Boolean) As Color
Dim red As Single = CSng(color.R)
Dim green As Single = CSng(color.G)
Dim blue As Single = CSng(color.B)
If (correctionFactor < 0) Then
correctionFactor = 1 + correctionFactor
If bR Then
red *= correctionFactor
End If
If bG Then
green *= correctionFactor
End If
If bB Then
blue *= correctionFactor
End If
Else
If bR Then
red = (255 - red) * correctionFactor + red
End If
If bG Then
green = (255 - green) * correctionFactor + green
End If
If bB Then
blue = (255 - blue) * correctionFactor + blue
End If
End If
Return color.FromArgb(color.A, CInt(red), CInt(green), CInt(blue))
End Function

How to Convert RGB Color to HSV?

How can I convert a RGB Color to HSV using C#?
I've searched for a fast method without using any external library.

Note that Color.GetSaturation() and Color.GetBrightness() return HSL values, not HSV.
The following code demonstrates the difference.
Color original = Color.FromArgb(50, 120, 200);
// original = {Name=ff3278c8, ARGB=(255, 50, 120, 200)}
double hue;
double saturation;
double value;
ColorToHSV(original, out hue, out saturation, out value);
// hue = 212.0
// saturation = 0.75
// value = 0.78431372549019607
Color copy = ColorFromHSV(hue, saturation, value);
// copy = {Name=ff3278c8, ARGB=(255, 50, 120, 200)}
// Compare that to the HSL values that the .NET framework provides:
original.GetHue(); // 212.0
original.GetSaturation(); // 0.6
original.GetBrightness(); // 0.490196079
The following C# code is what you want. It converts between RGB and HSV using the algorithms described on Wikipedia. The ranges are 0 - 360 for hue, and 0 - 1 for saturation or value.
public static void ColorToHSV(Color color, out double hue, out double saturation, out double value)
{
int max = Math.Max(color.R, Math.Max(color.G, color.B));
int min = Math.Min(color.R, Math.Min(color.G, color.B));
hue = color.GetHue();
saturation = (max == 0) ? 0 : 1d - (1d * min / max);
value = max / 255d;
}
public static Color ColorFromHSV(double hue, double saturation, double value)
{
int hi = Convert.ToInt32(Math.Floor(hue / 60)) % 6;
double f = hue / 60 - Math.Floor(hue / 60);
value = value * 255;
int v = Convert.ToInt32(value);
int p = Convert.ToInt32(value * (1 - saturation));
int q = Convert.ToInt32(value * (1 - f * saturation));
int t = Convert.ToInt32(value * (1 - (1 - f) * saturation));
if (hi == 0)
return Color.FromArgb(255, v, t, p);
else if (hi == 1)
return Color.FromArgb(255, q, v, p);
else if (hi == 2)
return Color.FromArgb(255, p, v, t);
else if (hi == 3)
return Color.FromArgb(255, p, q, v);
else if (hi == 4)
return Color.FromArgb(255, t, p, v);
else
return Color.FromArgb(255, v, p, q);
}

Have you considered simply using System.Drawing namespace? For example:
System.Drawing.Color color = System.Drawing.Color.FromArgb(red, green, blue);
float hue = color.GetHue();
float saturation = color.GetSaturation();
float lightness = color.GetBrightness();
Note that it's not exactly what you've asked for (see differences between HSL and HSV and the Color class does not have a conversion back from HSL/HSV but the latter is reasonably easy to add.

The EasyRGB has many color space conversions. Here is the code for the RGB->HSV conversion.

There's a C implementation here:
http://www.cs.rit.edu/~ncs/color/t_convert.html
Should be very straightforward to convert to C#, as almost no functions are called - just calculations.
found via Google

This is the VB.net version which works fine for me ported from the C code in BlaM's post.
There's a C implementation here:
http://www.cs.rit.edu/~ncs/color/t_convert.html
Should be very straightforward to convert to C#, as almost no functions are called - just > calculations.
Public Sub HSVtoRGB(ByRef r As Double, ByRef g As Double, ByRef b As Double, ByVal h As Double, ByVal s As Double, ByVal v As Double)
Dim i As Integer
Dim f, p, q, t As Double
If (s = 0) Then
' achromatic (grey)
r = v
g = v
b = v
Exit Sub
End If
h /= 60 'sector 0 to 5
i = Math.Floor(h)
f = h - i 'factorial part of h
p = v * (1 - s)
q = v * (1 - s * f)
t = v * (1 - s * (1 - f))
Select Case (i)
Case 0
r = v
g = t
b = p
Exit Select
Case 1
r = q
g = v
b = p
Exit Select
Case 2
r = p
g = v
b = t
Exit Select
Case 3
r = p
g = q
b = v
Exit Select
Case 4
r = t
g = p
b = v
Exit Select
Case Else 'case 5:
r = v
g = p
b = q
Exit Select
End Select
End Sub

I've ended up here by having the same need.
Bellow I'm sharing the best and simpler solution I could find so far.
This is a modified answer from Greg's (found here); but with a humbler and understandable code.
For those who are learning I've added a few references that are worth checking for the sake of understanding.
References
"Lukas Stratmann" HSV Model Tool (Incl. Other Model Systems: CMY / CMYK / HSL)
"The HSV Color Model in Graphic Design"
"Formula to Determine Perceived Brightness of RGB Color"
Fastest Formula to Get Hue from RGB
"Color Conversion Algorithms"
"Program to Change RGB color model to HSV color model"
"RGB to HSV Color Conversion Algorithm"
"RGB to HSV Color Space Conversion (C)"
"How to Convert RGB Color to HSV"
Code
/// <summary> Convert RGB Color to HSV. </summary>
/// <param name="color"></param>
/// <returns> A double[] Containing HSV Color Values. </returns>
public double[] rgbToHSV(Color color)
{
double[] output = new double[3];
double hue, saturation, value;
int max = Math.Max(color.R, Math.Max(color.G, color.B));
int min = Math.Min(color.R, Math.Min(color.G, color.B));
hue = color.GetHue();
saturation = (max == 0) ? 0 : 1d - (1d * min / max);
value = max / 255d;
output[0] = hue;
output[1] = saturation;
output[2] = value;
return output;
}

FIRST: make sure you have a color as a bitmap, like this:
Bitmap bmp = (Bitmap)pictureBox1.Image.Clone();
paintcolor = bmp.GetPixel(e.X, e.Y);
(e is from the event handler wich picked my color!)
What I did when I had this problem a whilke ago, I first got the rgba (red, green, blue and alpha) values.
Next I created 3 floats: float hue, float saturation, float brightness. Then you simply do:
hue = yourcolor.Gethue;
saturation = yourcolor.GetSaturation;
brightness = yourcolor.GetBrightness;
The whole lot looks like this:
Bitmap bmp = (Bitmap)pictureBox1.Image.Clone();
paintcolor = bmp.GetPixel(e.X, e.Y);
float hue;
float saturation;
float brightness;
hue = paintcolor.GetHue();
saturation = paintcolor.GetSaturation();
brightness = paintcolor.GetBrightness();
If you now want to display them in a label, just do:
yourlabelname.Text = hue.ToString;
yourlabelname.Text = saturation.ToString;
yourlabelname.Text = brightness.ToString;
Here you go, you now have RGB Values into HSV values :)
Hope this helps