c# - RGB to HSL and back, calculation problems -

-

i'm trying convert rgb hsl , want convert hsl rgb, have written class if rgb->hsl->rgb try if works different value.

example case: if create hslcolor object doing hslcolor mytestconversion = hslcolor.fromrgb(colors.green); , color expectedgreenhere = mytestconversion.torgb() different color colors.green while original input goes wrong..

this code i'm using:

public class hslcolor {     public float hue;     public float saturation;     public float luminosity;      public hslcolor(float h, float s, float l)     {         hue = h;         saturation = s;         luminosity = l;     }      public static hslcolor fromrgb(color clr)     {         return fromrgb(clr.r, clr.g, clr.b);     }      public static hslcolor fromrgb(byte r, byte g, byte b)     {         float _r = (r / 255f);         float _g = (g / 255f);         float _b = (b / 255f);          float _min = math.min(math.min(_r, _g), _b);         float _max = math.max(math.max(_r, _g), _b);         float _delta = _max - _min;          float h = 0;         float s = 0;         float l = (float)((_max + _min) / 2.0f);          if (_delta != 0)         {             if (l < 0.5f)             {                 s = (float)(_delta / (_max + _min));             }             else             {                 s = (float)(_delta / (2.0f - _max - _min));             }              float _delta_r = (float)(((_max - _r) / 6.0f + (_delta / 2.0f)) / _delta);             float _delta_g = (float)(((_max - _g) / 6.0f + (_delta / 2.0f)) / _delta);             float _delta_b = (float)(((_max - _b) / 6.0f + (_delta / 2.0f)) / _delta);              if (_r == _max)             {                 h = _delta_b - _delta_g;             }             else if (_g == _max)             {                 h = (1.0f / 3.0f) + _delta_r - _delta_b;             }             else if (_b == _max)             {                 h = (2.0f / 3.0f) + _delta_g - _delta_r;             }              if (h < 0) h += 1.0f;             if (h > 1) h -= 1.0f;         }          return new hslcolor(h, s, l);     }      private float hue_2_rgb(float v1, float v2, float vh)     {         if (vh < 0) vh += 1;         if (vh > 1) vh -= 1;         if ((6 * vh) < 1) return (v1 + (v2 - v1) * 6 * vh);         if ((2 * vh) < 1) return (v2);         if ((3 * vh) < 2) return (v1 + (v2 - v1) * ((2 / 3) - vh) * 6);         return (v1);     }      public color torgb()     {         color clr = new color();         float var_1, var_2;          if (saturation == 0)         {             clr.r = (byte)(luminosity * 255);             clr.g = (byte)(luminosity * 255);             clr.b = (byte)(luminosity * 255);         }         else         {             if (luminosity < 0.5) var_2 = luminosity * (1 + saturation);             else var_2 = (luminosity + saturation) - (saturation * luminosity);              var_1 = 2 * luminosity - var_2;              clr.r = (byte)(255 * hue_2_rgb(var_1, var_2, hue + (1 / 3)));             clr.g = (byte)(255 * hue_2_rgb(var_1, var_2, hue));             clr.b = (byte)(255 * hue_2_rgb(var_1, var_2, hue - (1 / 3)));         }          return clr;     } }

used reference: easyrgb color math

besides precision issues think actual algorithm incorrect. should fromrgb:

    public static hslcolor fromrgb(byte r, byte g, byte b)     {         float _r = (r / 255f);         float _g = (g / 255f);         float _b = (b / 255f);          float _min = math.min(math.min(_r, _g), _b);         float _max = math.max(math.max(_r, _g), _b);         float _delta = _max - _min;          float h = 0;         float s = 0;         float l = (float)((_max + _min) / 2.0f);          if (_delta != 0)         {             if (l < 0.5f)             {                 s = (float)(_delta / (_max + _min));             }             else             {                 s = (float)(_delta / (2.0f - _max - _min));             }               if (_r == _max)             {                 h = (_g - _b) / _delta;             }             else if (_g == _max)             {                 h = 2f + (_b - _r) / _delta;             }             else if (_b == _max)             {                 h = 4f + (_r - _g) / _delta;             }         }          return new hslcolor(h, s, l);     }

the next thing need understand we're taking integer rgb values 0 255 , converting them decimal values 0 1. hsl need converted normal degree/percent/percent you're used to. h value returned should 0 6 convert degrees multiply 60. h can negative if add 360;

            //convert degrees             h = h * 60f;             if (h < 0) h += 360;

s , l need multiplied 100 give percentage 0 100.

update

this code should hsl rgb. assumes hsl values still in decimal format. also, used double instead of float in code below better precision.

    public color torgb()     {         byte r, g, b;         if (saturation == 0)         {             r = (byte)math.round(luminosity * 255d);             g = (byte)math.round(luminosity * 255d);             b = (byte)math.round(luminosity * 255d);         }         else         {             double t1, t2;             double th = hue / 6.0d;              if (luminosity < 0.5d)             {                 t2 = luminosity * (1d + saturation);             }             else             {                 t2 = (luminosity + saturation) - (luminosity * saturation);             }             t1 = 2d * luminosity - t2;              double tr, tg, tb;             tr = th + (1.0d / 3.0d);             tg = th;             tb = th - (1.0d / 3.0d);              tr = colorcalc(tr, t1, t2);             tg = colorcalc(tg, t1, t2);             tb = colorcalc(tb, t1, t2);             r = (byte)math.round(tr * 255d);             g = (byte)math.round(tg * 255d);             b = (byte)math.round(tb * 255d);         }         return color.fromargb(r, g, b);     }     private static double colorcalc(double c, double t1, double t2)     {          if (c < 0) c += 1d;         if (c > 1) c -= 1d;         if (6.0d * c < 1.0d) return t1 + (t2 - t1) * 6.0d * c;         if (2.0d * c < 1.0d) return t2;         if (3.0d * c < 2.0d) return t1 + (t2 - t1) * (2.0d / 3.0d - c) * 6.0d;         return t1;     }

Comments

Post a Comment

Popular posts from this blog

java - SNMP4J General Variable Binding Error -

-
i trying use snmp4j snmp bulkget. when ever use snmp4j make call returned responseevent error says "general variable binding error" , data returned equal null. to debug: print out, console, exact oid , version number using in snmp4j. use printed out data snmpwalk on command line. valid results. know sending snmp4j correct pdu correct oid, version number, max repititions, etc. i have used snmp4j , code wrote succesffuly monitor other devices years. don't know different time. leaving me stumped. why "general variable binding error?" causes error? ideas debug? can reproduced? if so, first action should using wireshark or microsoft network monitor capture network packets. my guess agent gives generr response, not surprising, http://www.ietf.org/rfc/rfc1157.txt
Read more

windows - Python Service Installation - "Could not find PythonClass entry" -

-
i working on building python service. inducing error, not sure inducing it. ps c:\...> python .\file.py debug debugging service myservice - press ctrl+c stop. error 0xc00000f4 - not find service's pythonclass entry in registry error 1814 - specified resource name cannot found in image file. error 0xc0000080 - not locate module name in python class string (ie, no '.') this error coming pythonservicemessages.mc in pythonwin32. it turns out error result caused exception being thrown , python script dying off.
Read more

Determine if a XmlNode is empty or null in C#? -

-
the following code takes xmlnode data type , populates dataset object xmlnode content. write dataset's content file. public void populatedataset(xmlnode node) { xmlnodereader reader = new xmlnodereader(node); dataset ds = new dataset(); ds.readxml(reader); system.guid guid = system.guid.newguid(); string name = string.format("{0}{1}_{2}.xml", utility.xmloutputpath, utility.xmloutputfilename, guid.tostring()); //need write "node empty" file if xmlnode object empty of null ds.writexml(name, xmlwritemode.ignoreschema); } the problem encountered 1 scenario not write content file. how determine if xmlnode object null or empty? you can check if node parameter null or has innertext or innerxml properties null or empty, when enter method before creating xmlnodereader .
Read more