My rendered image and render to texture loses exactly one pixel in both width and height

Question

I have converted an UYVY image to RGB in pixel shader and the rendered target to texture of RGB bitmap loses exactly one pixel both in width and height.

I have tried if it's an issue of viewport or not. Before rendering the viewport first four floats (TopLeftX, TopLeftY, Width, Height) are (0.0f, 0.0f, 768.0f, 576.0f). I have checked the conversion algorithm from UYVY to RGB in shader. If something wrong with shader algorithm the image will show wrong pixel pixel data which is not. But I am worried about the sampler description I have used. My Sampler Description is following:

const D3D11_SAMPLER_DESC samplerDesc = {
            D3D11_FILTER_MIN_MAG_POINT_MIP_LINEAR,
            D3D11_TEXTURE_ADDRESS_WRAP, 
            D3D11_TEXTURE_ADDRESS_WRAP, 
            D3D11_TEXTURE_ADDRESS_WRAP,
            0, 1, D3D11_COMPARISON_NEVER,
            {0.0f, 0.0f, 0.0f, 0.0f}, 0, FLT_MAX };

I am losing exactly one pixel width and one pixel height. My converted image target 768 x 576. But the image is showing 767 x 575. The one pixel of black border is showing to the right and bottom in render to image and also in rendering. The one pixel border has black color because I have cleared target view initially in black color.

If anyone can pin point where should I look at to fix this issue it will helpful for me.

Update:

Input layout:

const std::array<D3D11_INPUT_ELEMENT_DESC, 2> PosTexMixVideoLayout =
{
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
        { "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0 },
    }
};

Input structure:

struct VSPosTextOverlay
{
    float4 position : POSITION0;
    float2 texOverlay : TEXCOORD0;
    float2 texImage : TEXCOORD1;
};

struct VSPosVideoTexture
{
    float4 position : POSITION0;
    float2 texOverlay : TEXCOORD0;
    float2 texImage : TEXCOORD1;
};

UYVY to RGB conversion in pixel shader:

/// <summary>Function to convert Uyvy to Rgb.</summary>
/// <param name="texImage">The tex image.</param>
/// <returns>A float4 value of RGB.</returns>
/// <remarks>
/// This function converts the Uyvy data contained in the input X8R8G8B8 texture
/// to Rgb. For even pixels the luminance value .g ist used, for odd pixels .a.
///
///      Formula for color values in the range 0-255:
///      R = 1.164(Y-16) + 1.596(Cr-128)
///      G = 1.164(Y-16) - 0.813(Cr-128) - 0.391(Cb-128)
///      B = 1.164(Y-16) + 2.018(Cb-128)
///      Note that the color values returned from the texture sampler are
///      in the range 0-1.
/// </remarks>
static inline float4 Uyvy2Rgb(in float2 texImage)
{
    // check whether we render an odd or even pixel
    // odd == 0.0 for even and odd == 1.0 for odd pixels
    float odd = step(frac(texImage.x * halfWidth), 0.5f);

    float4 uyvyColor = float4(uyvyImageTexture.Sample(uyvyImageSampler, texImage));

    float y = lerp(uyvyColor.a, uyvyColor.g, odd);

    y = 1.164f * (y - 0.0625f);
    uyvyColor.r -= 0.5f;
    uyvyColor.b -= 0.5f;
    uyvyColor.r *= saturation;
    uyvyColor.b *= saturation;

    float4 rgbColor;
    rgbColor.a = 1.0f;
    rgbColor.r = y + 1.596f * uyvyColor.r;
    rgbColor.g = y - 0.813f * uyvyColor.r - 0.391f * uyvyColor.b;
    rgbColor.b = y + 2.018f * uyvyColor.b;
    return rgbColor;
}

...is the bitmap format essentially array of cstring? or constructed with memcpy? — l.k
@Liton I have cleared target in black color before rendering. That's why it's black. — Tajuddin Khandaker
@l.k the bitmap data is array of BYTE and pixel bit format 32 BPP — Tajuddin Khandaker

Tajuddin Khandaker Tajuddin Khandaker · Accepted Answer · 2019-06-26T09:06:54

Due to half pixel issue DirectX 9 needed an offset to adjust drawings inside viewport. That offset is the reason to looks like loosing 1 pixel to the right and left scaled from viewport in DirectX 11 implementation as it's solved in DirectX later versions. Thus it looks like a 1 pixel border in background color. If we remove applying the offsets - the border will no longer exist.

My rendered image and render to texture loses exactly one pixel in both width and height

1 Answers