diff --git a/modules/gmt/colortransform.h b/modules/gmt/colortransform.h
new file mode 100644
index 0000000..b49dd20
--- /dev/null
+++ b/modules/gmt/colortransform.h
@@ -0,0 +1,135 @@
+// From grayscale
+struct gmt_color Gray2RGB() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=RGB;
+ color.r=color.g=color.b=gray;
+ return color;
+}
+struct gmt_color Gray2HSV() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=HSV;
+ color.hue=0;
+ color.saturation=0;
+ color.value=gray/255.0;
+ return color;
+}
+struct gmt_color Gray2CMYK() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=CMYK;
+ color.cyan=color.magenta=color.yellow=0;
+ color.black=(1.0-gray/255.0)*100.0;
+ return color;
+}
+
+// From RGB
+struct gmt_color RGB2Gray() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=GRAY;
+ color.gray=0.2126*r+0.7152*g+0.0722*b;
+ return color;
+}
+struct gmt_color RGB2HSV() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=HSV;
+ double rr=r/255.0,gg=g/255.0,bb=b/255.0;
+ double cmax=std::max(rr,std::max(gg,bb));
+ double cmin=std::min(rr,std::min(gg,bb));
+ double delta=cmax-cmin;
+
+ if(0==delta) color.hue=0;
+ else if(cmax==rr)
+ {
+  double x=(gg-bb)/delta;
+  color.hue=x-floor(x/6.0)*6.0;
+ }
+ else if(cmax==gg) color.hue=(bb-rr)/delta+2.0;
+ else if(cmax==bb) color.hue=(rr-gg)/delta+4.0;
+ color.hue*=60.0;
+ color.saturation=(0==cmax)?0:(delta/cmax);
+ color.value=cmax;
+
+ return color;
+}
+struct gmt_color RGB2CMYK() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=CMYK;
+ double rr=r/255.0,gg=g/255.0,bb=b/255.0;
+ double k=1.0-std::max(rr,std::max(gg,bb));
+
+ color.black=k;
+ color.cyan=(1.0-rr-k)/(1.0-k);
+ color.magenta=(1.0-gg-k)/(1.0-k);
+ color.yellow=(1.0-bb-k)/(1.0-k);
+ if(0.0==1.0-k) color.cyan=color.magenta=color.yellow=0.0;
+ color.black*=100.0;
+ color.cyan*=100.0;
+ color.magenta*=100.0;
+ color.yellow*=100.0;
+
+ return color;
+}
+
+// From HSV
+struct gmt_color HSV2Gray() const
+{
+ return HSV2RGB().RGB2Gray();
+}
+struct gmt_color HSV2RGB() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=RGB;
+ double c=saturation*value;
+ double x=c*(1.0-fabs((hue/60.0)-floor((hue/60.0)/2.0)*2.0-1.0));
+ double m=value-c;
+
+ if(0.0  <=hue && 60.0 >hue) {color.r=c; color.g=x; color.b=0;}
+ if(60.0 <=hue && 120.0>hue) {color.r=x; color.g=c; color.b=0;}
+ if(120.0<=hue && 180.0>hue) {color.r=0; color.g=c; color.b=x;}
+ if(180.0<=hue && 240.0>hue) {color.r=0; color.g=x; color.b=c;}
+ if(240.0<=hue && 300.0>hue) {color.r=x; color.g=0; color.b=c;}
+ if(300.0<=hue &&360.0>=hue) {color.r=c; color.g=0; color.b=x;}
+ color.r+=m; color.g+=m; color.b+=m;
+ color.r*=255; color.g*=255; color.b*=255;
+
+ return color;
+}
+struct gmt_color HSV2CMYK() const
+{
+ return HSV2RGB().RGB2CMYK();
+}
+
+// From CMYK
+struct gmt_color CMYK2Gray() const
+{
+ return CMYK2RGB().RGB2Gray();
+}
+struct gmt_color CMYK2RGB() const
+{
+ struct gmt_color color;
+ color.transparency=transparency;
+ color.model=RGB;
+ double cc=cyan/100.0,mm=magenta/100.0,yy=yellow/100.0,kk=black/100.0;
+
+ color.r=255.0*(1.0-cc)*(1.0-kk);
+ color.g=255.0*(1.0-mm)*(1.0-kk);
+ color.b=255.0*(1.0-yy)*(1.0-kk);
+
+ return color;
+}
+struct gmt_color CMYK2HSV() const
+{
+ return CMYK2RGB().RGB2HSV();
+}
diff --git a/modules/gmt/modgmt_structs.h b/modules/gmt/modgmt_structs.h
new file mode 100644
index 0000000..21c5b68
--- /dev/null
+++ b/modules/gmt/modgmt_structs.h
@@ -0,0 +1,382 @@
+#ifndef MODGMT_STRUCT_H
+#define MODGMT_STRUCT_H
+#include <cinttypes>
+
+// Coordinate
+struct gmt_coord
+{
+ bool isdeg;
+ union
+ {
+  double r;
+  struct
+  {
+   bool sign;
+   uint16_t d;
+   uint8_t m;
+   double s;
+  };
+ };
+
+ std::string Value() const
+ {
+  if(!isdeg) return std::to_string(r);
+  else return (sign?"":"-")+std::to_string(d)+":"+std::to_string(m)+(s==0?"":":"+std::to_string(s));
+ }
+ operator double() const
+ {
+  if(isdeg) return (d+(m+s/60.0)/60.0)*(sign?1:-1);
+  else return r;
+ }
+ bool Convert(const std::string& str)
+ {
+  size_t bpos=0,pos=str.find(':');
+  if(std::string::npos==pos)
+  {
+   isdeg=false;
+   return str2double(str,&r);
+  }
+
+  isdeg=true;
+  int64_t res;
+
+  // degrees
+  if(! str2int(std::string(str.c_str(),str.c_str()+pos),&res) ) return false;
+  if(res>360 || res<-360) res%=360;
+  sign=(std::string::npos==str.find('-'));
+  d=static_cast<uint16_t>(sign?res:-res);
+  // minutes
+  bpos=pos+1;
+  pos=str.find(':',bpos);
+  if(std::string::npos==pos)
+  {
+   if(!str2int(str.substr(bpos),&res)) return false;
+   if(res<0 || res>=60) return false;
+   m=static_cast<uint8_t>(res);
+   s=0;
+   return true;
+  }
+  if(! str2int(std::string(str.c_str()+bpos,str.c_str()+pos),&res) ) return false;
+  if(res<0 || res>=60) return false;
+  m=static_cast<uint8_t>(res);
+  // seconds
+  if(! str2double(str.substr(pos+1),&s) ) return false;
+  if(s<0.0 || s>=60.0) return false;
+  return true;
+ }
+ bool Convert(double num)
+ {
+  isdeg=false;
+  r=num;
+  return true;
+ }
+};
+
+
+// Region
+struct gmt_region
+{
+ enum Type {NORMAL,BBOX,GLOBAL360,GLOBAL180};
+ Type type;
+ struct gmt_coord xb,xe,yb,ye;
+
+ std::string Value() const
+ {
+  switch(type)
+  {
+   case(NORMAL): return std::string("-R")+xb.Value()+"/"+xe.Value()+"/"+yb.Value()+"/"+ye.Value();
+   case(BBOX): return std::string("-R")+xb.Value()+"/"+yb.Value()+"/"+xe.Value()+"/"+ye.Value()+"r";
+   case(GLOBAL360): return "-Rg";
+   case(GLOBAL180): return "-Rd";
+  }
+  return "";
+ }
+
+ // Only "global", "global180" and "global360"
+ // TODO: add parsing of "-R" strings
+ bool Convert(const std::string& istr)
+ {
+  std::string str=istr;
+  tolower(str);
+  if("global180"==str)
+  {
+   type=GLOBAL180;
+   xb.Convert(-180.0); xe.Convert(180.0);
+   yb.Convert(-90.0); ye.Convert(90.0);
+   return true;
+  }
+  if("global360"==str || "global"==str)
+  {
+   type=GLOBAL360;
+   xb.Convert(0.0); xe.Convert(360.0);
+   yb.Convert(-90.0); ye.Convert(90.0);
+   return true;
+  }
+  return false;
+ }
+
+ // Make by coordinates
+ bool Convert(struct gmt_coord ixb, struct gmt_coord ixe, struct gmt_coord iyb, struct gmt_coord iye, bool isbbox=false)
+ {
+  type=isbbox?BBOX:NORMAL;
+  xb=ixb; yb=iyb; xe=ixe; ye=iye;
+  return true;
+ }
+};
+
+
+// Projection
+struct gmt_projection
+{
+ // OBLIQMERCATOR types
+ enum class OType {A,B,C};
+ // No UTM (-Ju)
+ enum projection {XY,CYL_EQU,MERCATOR,TRANSMERCATOR,OBLIQMERCATOR,CASSINI,CYL_EQA,MILLER,CYL_STERE};
+ // Real size in cm of drawing area
+ double rwidth,rheight;
+
+ struct gmt_region region;
+ projection proj;
+ double width; // parameter of projection
+
+ union // other projection parameters
+ {
+  // XY
+  struct {double height;} x;
+  // Cylindrical projections
+  // CYL_EQU (Cylindrical Equidistant -Jq)
+  struct {double stpar,cmer;} q;
+  // MERCATOR (-Jm)
+  struct {double stpar,cmer;} m;
+  // TRANSMERCATOR (-Jt)
+  struct {double cmer,orlat,scale;} t;
+  // OBLIQMERCATOR (-Jo)
+  struct
+  {
+   OType type;
+   double clon,clat;
+   union
+   {
+    double azimuth; // A
+    struct {double eqlon,eqlat;}; // B
+    struct {double polelon,polelat;}; // C
+   };
+  } o;
+  // CASSINI (-Jc)
+  struct {double clon,clat;} c;
+  // CYL_EQA (Cylindrical equal-area -Jy)
+  struct {double stpar,cmer;} y;
+  // MILLER (-Jj)
+  struct {double cmer;} j;
+  // CYL_STERE (Cylindrical stereographic -Jcyl_stere)
+  struct {double stpar,cmer;} cyl_stere;
+ };
+ std::string Value() const
+ {
+  switch(proj)
+  {
+   case(XY): return "-JX"+std::to_string(width)+"c/"+std::to_string(x.height)+"c";
+   case(CYL_EQU): return "-JQ"+std::to_string(q.cmer)+"/"+std::to_string(q.stpar)+"/"+std::to_string(width)+"c";
+   case(MERCATOR): return "-JM"+std::to_string(m.cmer)+"/"+std::to_string(m.stpar)+"/"+std::to_string(width)+"c";
+   case(TRANSMERCATOR): return "-JT"+std::to_string(t.cmer)+"/"+std::to_string(t.orlat)+"/"+std::to_string(width)+"c --PROJ_SCALE_FACTOR="+std::to_string(t.scale);
+   case(OBLIQMERCATOR):
+   {
+    switch(o.type)
+    {
+     case(OType::A): return "-JOa"+std::to_string(o.clon)+"/"+std::to_string(o.clat)+"/"+std::to_string(o.azimuth)+"/"+std::to_string(width)+"c";
+     case(OType::B): return "-JOb"+std::to_string(o.clon)+"/"+std::to_string(o.clat)+"/"+std::to_string(o.eqlon)+"/"+std::to_string(o.eqlat)+"/"+std::to_string(width)+"c";
+     case(OType::C): return "-JOb"+std::to_string(o.clon)+"/"+std::to_string(o.clat)+"/"+std::to_string(o.polelon)+"/"+std::to_string(o.polelat)+"/"+std::to_string(width)+"c";
+    }
+   }
+   case(CASSINI): return "-JC"+std::to_string(c.clon)+"/"+std::to_string(c.clat)+"/"+std::to_string(width)+"c";
+   case(CYL_EQA): return "-JY"+std::to_string(y.stpar)+"/"+std::to_string(y.cmer)+"/"+std::to_string(width)+"c";
+   case(MILLER): return "-JJ"+std::to_string(j.cmer)+"/"+std::to_string(width)+"c";
+   case(CYL_STERE): return "-JCyl_stere"+std::to_string(cyl_stere.stpar)+"/"+std::to_string(cyl_stere.cmer)+"/"+std::to_string(width)+"c";
+  }
+  return "";
+ }
+};
+
+
+// Color
+struct gmt_color
+{
+ enum ColorModel {RGB,GRAY,HSV,CMYK};
+ ColorModel model;
+ union
+ {
+  double gray; // 0-255
+  struct {double r,g,b;}; // 0-255
+  struct {double hue,saturation,value;}; // 0-360, 0-1, 0-1
+  struct {double cyan,magenta,yellow,black;}; // 0-100
+ };
+ double transparency;
+ std::string Value() const
+ {
+  std::string trans=(transparency!=0)?("@"+std::to_string(transparency)):"";
+  switch(model)
+  {
+   case(RGB): return std::to_string(r)+"/"+std::to_string(g)+"/"+std::to_string(b)+trans;
+   case(GRAY): return std::to_string(gray)+trans;
+   case(HSV): return std::to_string(hue)+"-"+std::to_string(saturation)+"-"+std::to_string(value)+trans;
+   case(CMYK): return std::to_string(cyan)+"/"+std::to_string(magenta)+"/"+std::to_string(yellow)+"/"+std::to_string(black)+trans;
+  }
+  return "";
+ }
+ double Gray() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2Gray().gray;
+   case(GRAY): return gray;
+   case(HSV):  return HSV2Gray().gray;
+   case(CMYK): return CMYK2Gray().gray;
+  }
+  return 0;
+ }
+
+ double R() const
+ {
+  switch(model)
+  {
+   case(RGB):  return r;
+   case(GRAY): return Gray2RGB().r;
+   case(HSV):  return HSV2RGB().r;
+   case(CMYK): return CMYK2RGB().r;
+  }
+  return 0;
+ }
+ double G() const
+ {
+  switch(model)
+  {
+   case(RGB):  return g;
+   case(GRAY): return Gray2RGB().g;
+   case(HSV):  return HSV2RGB().g;
+   case(CMYK): return CMYK2RGB().g;
+  }
+  return 0;
+ }
+ double B() const
+ {
+  switch(model)
+  {
+   case(RGB):  return b;
+   case(GRAY): return Gray2RGB().b;
+   case(HSV):  return HSV2RGB().b;
+   case(CMYK): return CMYK2RGB().b;
+  }
+  return 0;
+ }
+
+ double H() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2HSV().hue;
+   case(GRAY): return Gray2HSV().hue;
+   case(HSV):  return hue;
+   case(CMYK): return CMYK2HSV().hue;
+  }
+  return 0;// Own functions
+ }
+ double S() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2HSV().saturation;
+   case(GRAY): return Gray2HSV().saturation;
+   case(HSV):  return saturation;
+   case(CMYK): return CMYK2HSV().saturation;
+  }
+  return 0;
+ }
+ double V() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2HSV().value;
+   case(GRAY): return Gray2HSV().value;
+   case(HSV):  return value;
+   case(CMYK): return CMYK2HSV().value;
+  }
+  return 0;
+ }
+
+ double C() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2CMYK().cyan;
+   case(GRAY): return Gray2CMYK().cyan;
+   case(HSV):  return HSV2CMYK().cyan;
+   case(CMYK): return cyan;
+  }
+  return 0;
+ }
+ double M() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2CMYK().magenta;
+   case(GRAY): return Gray2CMYK().magenta;
+   case(HSV):  return HSV2CMYK().magenta;
+   case(CMYK): return magenta;
+  }
+  return 0;
+ }
+ double Y() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2CMYK().yellow;
+   case(GRAY): return Gray2CMYK().yellow;
+   case(HSV):  return HSV2CMYK().yellow;
+   case(CMYK): return yellow;
+  }
+  return 0;
+ }
+ double K() const
+ {
+  switch(model)
+  {
+   case(RGB):  return RGB2CMYK().black;
+   case(GRAY): return Gray2CMYK().black;
+   case(HSV):  return HSV2CMYK().black;
+   case(CMYK): return black;
+  }
+  return 0;
+ }
+ // Transformation functions
+ private:
+#include "colortransform.h"
+};
+
+
+// Dash
+struct gmt_dash
+{
+ std::vector<double> dash;
+ double shift;
+ std::string Value() const
+ {
+  std::string ret;
+  if(dash.empty()) return ret;
+  for(auto i:dash) ret+=std::to_string(i)+"_";
+  ret.back()=':';
+  ret+=std::to_string(shift)+"c";
+  return ret;
+ }
+ operator bool() const {return !dash.empty();}
+};
+
+
+// Pen
+struct gmt_pen
+{
+ double width;
+ struct gmt_color color;
+ struct gmt_dash dash;
+ std::string Value() const {return std::to_string(width)+","+color.Value()+(dash?(","+dash.Value()):"");}
+};
+#endif