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    Dither H

    Uploaded by

    Mohamed Ouattara
    This shader performs dithering to increase the apparent bit depth of colors beyond 8 bits per channel. It implements either random dithering using pseudo-random noise or ordered dithering based on texture coordinates. Dithering works by applying a small color shift based on the dither pattern to blend between color levels. The amount of shift scales with the number of bits per channel being simulated.

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    © All Rights Reserved
    Download as TXT, PDF, TXT or read online from Scribd

    Dither H

    Uploaded by

    Mohamed Ouattara
    10 views2 pages
    This shader performs dithering to increase the apparent bit depth of colors beyond 8 bits per channel. It implements either random dithering using pseudo-random noise or ordered dithering based on texture coordinates. Dithering works by applying a small color shift based on the dither pattern to blend between color levels. The amount of shift scales with the number of bits per channel being simulated.

    Original Description:

    Original Title

    Dither.h

    Copyright

    © © All Rights Reserved

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    This shader performs dithering to increase the apparent bit depth of colors beyond 8 bits per channel. It implements either random dithering using pseudo-random noise or ordered dithering based on texture coordinates. Dithering works by applying a small color shift based on the dither pattern to blend between color levels. The amount of shift scales with the number of bits per channel being simulated.

    Copyright:

    © All Rights Reserved
    Download as TXT, PDF, TXT or read online from Scribd
    Download as txt, pdf, or txt
    10 views2 pages

    Dither H

    Uploaded by

    Mohamed Ouattara
    This shader performs dithering to increase the apparent bit depth of colors beyond 8 bits per channel. It implements either random dithering using pseudo-random noise or ordered dithering based on texture coordinates. Dithering works by applying a small color shift based on the dither pattern to blend between color levels. The amount of shift scales with the number of bits per channel being simulated.

    Copyright:

    © All Rights Reserved
    Download as TXT, PDF, TXT or read online from Scribd
    Download as txt, pdf, or txt
    of 2

    /*-----------------------------------------------------------.

    / Dither /
    '-----------------------------------------------------------*/
    /*
    Dither version 1.2.0
    by Christian Cann Schuldt Jensen ~ CeeJay.dk

    Does dithering of the greather than 8-bit per channel precision used in shaders.
    Even halfs offer 10(+1)bit per channel
    */

    float4 DitherPass( float4 colorInput, float2 tex )


    {
    float3 color = colorInput.rgb;

    //color = (tex.x / 2.0); //draw a gradient for testing.

    float dither_size = 2.0; //Size of the dithering grid - I'm using a 2x2 grid
    here.
    float dither_bit = 8.0; //Number of bits per channel. Should be 8 for most
    monitors.

    #if dither_method == 2 //random dithering

    //make some noise


    float noise = frac(sin(dot(float4(tex,-tex.yx),
    float4(float2(12.9898,78.233),float2(12.9898,78.233)* acos(-1)))) *
    43758.5453); //pseudo random number generator
    noise -= 0.5;

    /*
    //Calculate grid position
    float grid_position = frac(dot(tex,(screen_size / dither_size)) + (0.5 /
    dither_size)); //returns 0.25 and 0.75

    //modify noise for extra dithering


    noise = lerp(2.0 * noise, -2.0 * noise, grid_position); //do i really need to
    use the gridposition with noise? - signs point to no.
    */

    //Calculate how big the shift should be


    float dither_shift = (noise) * (1.0 / (pow(2,dither_bit) - 1.0)); // using
    noise to determine shift. The noise ahould vary between +- 0.5.

    //Shift the individual colors differently, thus making it even harder to see
    the dithering pattern
    float3 dither_shift_RGB = float3(-dither_shift, dither_shift, -
    dither_shift); //subpixel dithering

    //shift the color by dither_shift


    //dither_shift_RGB = lerp(2.0 * dither_shift_RGB, -2.0 * dither_shift_RGB,
    grid_position); //do i really need to use the gridposition with noise?
    color.rgb += dither_shift_RGB;

    #else //dither_method == 1 , Ordered dithering


    //Calculate grid position
    float grid_position = frac(dot(tex,(screen_size / dither_size)) + (0.5 /
    dither_size)); //returns 0.25 and 0.75
    //Calculate how big the shift should be
    float dither_shift = (0.25) * (1.0 / (pow(2,dither_bit) - 1.0)); // 0.25 seems
    good both when using math and when eyeballing it. So does 0.75 btw.

    //Shift the individual colors differently, thus making it even harder to see
    the dithering pattern
    float3 dither_shift_RGB = float3(dither_shift, -dither_shift,
    dither_shift); //subpixel dithering

    //modify shift acording to grid position.


    dither_shift_RGB = lerp(2.0 * dither_shift_RGB, -2.0 * dither_shift_RGB,
    grid_position); //shift acording to grid position.

    //shift the color by dither_shift


    //color.rgb += lerp(2.0 * dither_shift_RGB, -2.0 * dither_shift_RGB,
    grid_position); //shift acording to grid position.
    color.rgb += dither_shift_RGB;
    #endif

    //colorInput.rgb = (dither_shift_RGB * 2.0 * (pow(2,dither_bit) - 1.0) ) +


    0.5; //visualize the shift
    //colorInput.rgb = grid_position; //visualize the grid
    //colorInput.rgb = noise; //visualize the noise

    colorInput.rgb = color.rgb;

    return colorInput;
    }

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