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RGB-Gray Linear Interpolation

Reptillian

By Reptillian
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Reptillian Mentor

Reptillian

Posted
Posted (edited)

Inspired by @ReMake, I have decided to take my version which contains more variety. (Two different source codes for this is provided below. C# and G'MIC-QT). All this filter does is to interpolate between rgb and grayscale value.

 

67vCWrZ.png

 

Download - RGB to Linear Interpolation.dll

It's under Effects/Colors

 

------

License - CeCiLLv2.0 - https://cecill.info/licences/Licence_CeCILL_V2-en.html

Source code in C#

 

 

 // Name: RGB-Gray Linear Interpolation
// Submenu: Effects\Colors
// Author: Reptorian
// Title: RGB to Gray Linear Interpolation
// Version: 1.0
// Desc: Interpolate between rgb value and grayscale value
// Keywords: interpolation,adjustment
// URL: forums.getpaint.net
// Help:
#region UICode
ListBoxControl Mode = 1; // GrayMode|Weighted|Luminosity A|Luminosity B|HSL Lightness|Minimum Channel|Maximum Channel|Average
IntSliderControl RedFactor = 255; // [0,360] Red Factor
IntSliderControl GreenFactor = 255; // [0,360] Green Factor
IntSliderControl BlueFactor = 255; // [0,360] Blue Factor
DoubleSliderControl RedWeight = 1; // [0,1] {Mode} Red Weight
DoubleSliderControl GreenWeight = 1; // [0,1] {Mode} Green Weight
DoubleSliderControl BlueWeight = 1; // [0,1] {Mode} Blue Weight
#endregion


private int Weighted(int rval,int gval, int bval, double rw, double gw, double bw)
{
    double rfactor=(double)(rw*rval);
    double gfactor=(double)(gw*gval);
    double bfactor=(double)(bw*bval);
    double endval=rfactor+gfactor+bfactor;
    return (int)(endval);
}


private int Luma_A(int rval,int gval, int bval)
{
    double rfactor=(double)(0.22248840*rval);
    double gfactor=(double)(0.71690369*gval);
    double bfactor=(double)(0.06060791*bval);
    double endval=rfactor+gfactor+bfactor;
    return (int)(endval);
}

private int Luma_B(int rval,int gval, int bval)
{
    double rfactor=(double)(0.2989*rval);
    double gfactor=(double)(0.5870*gval);
    double bfactor=(double)(0.1140*bval);
    double endval=rfactor+gfactor+bfactor;
    return (int)(endval);
}

private int lightness(int rval,int gval, int bval)
{
    int max_factor=Math.Max(Math.Max(rval,gval),Math.Max(gval,bval));
    int min_factor=Math.Min(Math.Min(rval,gval),Math.Min(gval,bval));
    double grayval=(double)((max_factor+min_factor)/2);
    return (int)(grayval);
}

private int max(int rval,int gval, int bval)
{
    return Math.Max(Math.Max(rval,gval),Math.Max(gval,bval));
}

private int min(int rval,int gval, int bval)
{
    return Math.Min(Math.Min(rval,gval),Math.Min(gval,bval));
}

private int average(int rval,int gval, int bval)
{
    double avg = (double)((rval+gval+bval)/3);
    return (int)(avg);
}

private ColorBgra Interpolation(int rval,int gval,int bval,int rlvl,int glvl,int blvl,int gray,int A)
{
    int rr = (rval * rlvl + gray * (255 - rlvl)) / 255;
    int gg = (gval * glvl + gray * (255 - glvl)) / 255;
    int bb = (bval * blvl + gray * (255 - blvl)) / 255;
    return ColorBgra.FromBgraClamped(bb,gg,rr,A);
}

void Render(Surface dst, Surface src, Rectangle rect)
{
    // Delete any of these lines you don't need
    Rectangle selection = EnvironmentParameters.SelectionBounds;
    int Gray=0;
    double totalweight=RedWeight+GreenWeight+BlueWeight;
    double red_weight=RedWeight/totalweight;
    double green_weight=GreenWeight/totalweight;
    double blue_weight=BlueWeight/totalweight;

    ColorBgra CurrentPixel;
    for (int y = rect.Top; y < rect.Bottom; y++)
    {
        if (IsCancelRequested) return;
        for (int x = rect.Left; x < rect.Right; x++)
        {
            CurrentPixel = src[x,y];
            int R=(int)(CurrentPixel.R);
            int G=(int)(CurrentPixel.G);
            int B=(int)(CurrentPixel.B);
            int A=(int)(CurrentPixel.A);

            switch (Mode)
            {
                case 0:
                    Gray = Weighted(R,G,B,red_weight,green_weight,blue_weight);
                    break;
                case 1:
                    Gray = Luma_A(R,G,B);
                    break;
                case 2:
                    Gray = Luma_B(R,G,B);
                    break;
                case 3:
                    Gray = lightness(R,G,B);
                    break;
                case 4:
                    Gray = min(R,G,B);
                    break;
                case 5:
                    Gray = max(R,G,B);
                    break;
                case 6:
                    Gray = average(R,G,B);
                    break;
            }

            ColorBgra Final=Interpolation(R,G,B,RedFactor,GreenFactor,BlueFactor,Gray,A);
            dst[x,y] = Final;
        }
    }
}

Source Code in G'MIC-QT

 

#@cli rep_lerp_rgb_gray: eq. to rep_linear_interpolation_rgb_gray : (+)
rep_lerp_rgb_gray: rep_linear_interpolation_rgb_gray $*
#@cli rep_linear_interpolation_rgb_gray: 0%>=_red_factor(%)<=100%,0%>=_green_factor(%)<=100%,0%>=_blue_factor(%)<=100%,_gray_mode={ 0=luminosity | 1=luminosity_alternative | 2=lightness | 3=minimum_channel | 4=maximum_channel | 5=average } : 0%>=_red_factor(%)<=100%,0%>=_green_factor(%)<=100%,0%>=_blue_factor(%)<=100%,_red_weight,green_weight,blue_weight
rep_linear_interpolation_rgb_gray:
skip ${4=0},${5=},${6=}
total_arg=0
if isnum($1) total_arg+=1 fi
if isnum($2) total_arg+=1 fi
if isnum($3) total_arg+=1 fi
if isnum($4) total_arg+=1 fi
if isnum($5) total_arg+=1 fi
if isnum($6) total_arg+=1 fi
if $total_arg==5 error "narg!=5=F" fi

 

if abs($1)>2 error "|"$"1|<=2=F" fi
if abs($2)>2 error "|"$"2|<=2=F" fi
if abs($3)>2 error "|"$"3|<=2=F" fi

 

f "
begin(
    rlvl=abs($1);
    glvl=abs($2);
    blvl=abs($3);
        
    if(narg($*)>5,
        tw=abs($4)+abs($5)+abs($6);
        c1f=abs($4)/tw;
        c2f=abs($5)/tw;
        c3f=abs($6)/tw;
        graymode(a,b,c)=a*c1f+b*c2f+c*c3f;
    ,        
        if($4==0,graymode(a,b,c)=a*0.22248840+b*0.71690369+c*0.06060791;,
        if($4==1,graymode(a,b,c)=a*0.2989+b*0.5870+c*0.1140;,
        if($4==2,graymode(a,b,c)=(max(a,b,c)+min(a,b,c))/2;,
        if($4==3,graymode(a,b,c)=min(a,b,c);,
        if($4==4,graymode(a,b,c)=max(a,b,c);,
                 graymode(a,b,c)=avg(a,b,c);
        );
        );
        );
        );
        );
    );
);
gl=graymode(i0,i1,i2);
[lerp(gl,i0,rlvl),lerp(gl,i1,glvl),lerp(gl,i2,blvl)]
"

 

#@gui RGB-Gray Linear Interpolation: fx_rep_lerp_rgb_gray,fx_rep_lerp_rgb_gray_preview(0)
#@gui : _=note("<b>Formula</b>")
#@gui : Mode=choice(0,"Luminosity A","Luminosity B","Lightness","Minimum","Maximum","Average",Weighted")
#@gui : Limit Factor to 100%=bool(0)
#@gui : sep=separator(),_=note("<b>Channel Factor</b>")
#@gui : Red Factor (%)=float(100,0,150)
#@gui : Green Factor (%)=float(100,0,150)
#@gui : Blue Factor (%)=float(100,0,150)
#@gui : Red Factor (%)=float(100,0,100)
#@gui : Green Factor (%)=float(100,0,100)
#@gui : Blue Factor (%)=float(100,0,100)
#@gui : Red Weight=float(1,0,1)
#@gui : Green Weight=float(100,0,1)
#@gui : Blue Weight=float(100,0,1)
#@gui : sep=separator(),_=note("<b>Preview</b>"),Preview Type=choice("Full","Forward Horizontal","Forward Vertical","Backward Horizontal","Backward Vertical","Duplicate Top","Duplicate Left","Duplicate Bottom","Duplicate Right","Duplicate Horizontal","Duplicate Vertical","Checkered","Checkered Inverse"), Preview Split=point(50,50,0,0,200,200,200,0,10)_0
#@gui : sep=separator(),note=note("<small>Author: Reptorian. Latest Update: <i>2020/14/3</i>.</small>")
fx_rep_lerp_rgb_gray:
if $1==6
    if $2 rep_lerp_rgb_gray $6%,$7%,$8%,${9-11}
    else  rep_lerp_rgb_gray $3%,$4%,$5%,${9-11}
    fi
else
    if $2 rep_lerp_rgb_gray $6%,$7%,$8%,$1
    else  rep_lerp_rgb_gray $3%,$4%,$5%,$1
    fi
fi
fx_rep_lerp_rgb_gray_preview:
gui_split_preview "fx_rep_lerp_rgb_gray ${1-11}",${-3--1}
u "{$1}"\
"{$2}"\
"{$3}_"{$2?0:2}\
"{$4}_"{$2?0:2}\
"{$5}_"{$2?0:2}\
"{$6}_"{$2?2:0}\
"{$7}_"{$2?2:0}\
"{$8}_"{$2?2:0}\
"{$9}_"{$1==6?2:0}\
"{$10}_"{$1==6?2:0}\
"{$11}_"{$1==6?2:0}\
"{$12}"\
"{$13,14}"

 

Edited by Reptillian
Typos elimination again...
  • Like 2
  • Upvote 1

G'MIC Filter Developer

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ReMake Mentor

ReMake

Posted
Posted

Some comments and suggestions:

Your code does not save transparent areas of the image by replacing them with white.

To fix this, add 

int A = CurrentPixel.A;

under 

int B = CurrentPixel.B;

Add int A after the gray variable in Interpolation() 

private ColorBgra Interpolation(int rval, int gval, int bval, int rlvl, int glvl, int blvl, int gray, int A)

and add A to ColorBgra Final 

ColorBgra Final = Interpolation(R, G, B, RedFactor, GreenFactor, BlueFactor, Gray, A);

The code snippet 

if(rr>255){rr=255;}
    if(rr<0){rr=0;}
    if(gg>255){gg=255;}
    if(gg<0){gg=0;}
    if(bb>255){bb=255;}
    if(bb<0){bb=0;}
    return ColorBgra.FromBgr((byte)(bb),(byte)(gg),(byte)(rr));

can be deleted and replaced with line 

return ColorBgra.FromBgraClamped(bb, gg, rr, A);

In Luma_A () and Luma_B () in the lines 

double bfactor=(double)(0.06060791*gval);

and 

double bfactor=(double) (0.1140*gval);

probably a typo (gval or bval)?

 

Interesting effect in any case.

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