TR's Coquin Graduated Filter

[TechnoRobbo]

TechnoRobbo's Coquin Graduated Filter

A simulation of the legendary Cokin Graduated Photographic Filter 

 

Back in the 70's a photographer named Jean Coquin invented a new style of filter called Cokin

 

http://en.wikipedia.org/wiki/Cokin

 

 

One of the most used filters in the Cokin is the graduated color filter.

 

http://www.cokin-filters.com/creative-system/

 

This simulation allows you to slide the filter up and down and rotate it just like the real fiter.

It does not add color to the picture it subtracts the complimentary colors simulating what a real photographic filter would do.

 

Menu: Effects -> Color

 

 

No instructions - just play around.

 

 

 

 

 

 

 

 

 

 

The Code

Hidden Content:

// Submenu: Color

// Name: TR's Coquin Filter 

// Title: TR's Coquin Filter - v1.0

// Author: TechnoRobbo

// URL: http://www.technorobbo


#region UICode

double Amount1 = 0; // [-1,1] Offset

ColorBgra Amount2 = ColorBgra.FromBgr(0,0,0); // Tint

double Amount3 = -90; // [-180,180] Rotation

#endregion


void Render(Surface dst, Surface src, Rectangle rect)

{

    // Delete any of these lines you don't need

    Rectangle sel = EnvironmentParameters.GetSelection(src.Bounds).GetBoundsInt();

    int CenterX = ((sel.Right - sel.Left) / 2)+sel.Left;

    int CenterY = ((sel.Bottom - sel.Top) / 2)+sel.Top;

    double rad = Amount3 * Math.PI/180;

    float shortside = (sel.Height > sel.Width) ? sel.Width : sel.Height;

    shortside +=(float)Amount1 * shortside;


    ColorBgra CP;

    for (int y = rect.Top; y < rect.Bottom; y++)

    {

        for (int x = rect.Left; x < rect.Right; x++)

        {

            //========================================

            PointF position = new PointF(x-CenterX,y-CenterY);

            position.X =(float)Math.Cos(rad) * position.X -(float)Math.Sin(rad) * position.Y + CenterX;


            //===========================================================


            float grad = 1-( position.X / shortside);

            grad = Math.Max(grad,0);

            grad = Math.Min(grad,1);


            CP = src[x,y];

            int  R = (int)((Amount2.B + Amount2.G)/2 * grad) ;   

            int  G =(int)((Amount2.B + Amount2.R)/2 * grad) ;

            int  B =(int)((Amount2.R + Amount2.G)/2 * grad) ;

            CP.R = Int32Util.ClampToByte((int)( CP.R - R ));

            CP.G = Int32Util.ClampToByte((int)( CP.G - G ));

            CP.B = Int32Util.ClampToByte((int)( CP.B - B ));

            dst[x,y] = CP;

        }

    }

}

TRsCoquin.zip

Edited December 28, 2015 by TechnoRobbo

[DrewDale]

Another top class plugin, very useful.

[dug]

Excellent, I have a collection of Cokin Filters for my old film camera.Now I can do it digitally.Nice one,cool plug-in.

Thank you for sharing.

[skullbonz]

I like how this plugin works, the rotation adjustment is a cool extra that sets this apart from other similar plugins. I started with a picture of blue sky, white clouds and bright sun, made this with several other plugins and then applied the Coquin Graduated Filter to the layers before merging them together. I love your plugins TR but I can't make pictures fast enough to keep up with you,lol, and I'm loving it.  

 

[TechnoRobbo]

Very nice - It looks real.

 

One interesting factoid. Coquin does not add color to the picture it subtracts the complimentary colors simulating what a real photographic filter would does.

 

(That sounded good. I'll add it to the description in the OP)

Edited August 2, 2013 by TechnoRobbo