# DX11 DXGI_FORMAT_R8_UNORM for luminance gives me only red channel

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Hi...
I am trying to load a texture with the DXGI_FORMAT_R8_UNORM to obtain its luminance version(grayScale), in D3D9 i was used D3DFMT_L8 and the result is okay but in D3D11 i only obtain the red channel, what i am doing wrong?

Rendered Color image:

here is the code:

	D3DX11_IMAGE_INFO* pImgInfo = 0;
HRESULT imghr = D3DX11GetImageInfoFromFile( L"Tiles.png", NULL, pImgInfo, NULL);

m_Texture = m_pRenderer11->LoadTexture( L"Tiles.png", &imgLoadInfo  );

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R8_UNORM means you have a texture with just a red channel. If you load an RGB texture with that format, you will only get the red channel from that texture. If you want a texture containing the luminance of the RGB values, you'll need to do that yourself.

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R8_UNORM means you have a texture with just a red channel. If you load an RGB texture with that format, you will only get the red channel from that texture. If you want a texture containing the luminance of the RGB values, you'll need to do that yourself.

Is there no a way like in D3D9 with the format  D3DFMT_L8? when i used these forma to load a texture it visually return a gray scale version

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Use the R value from your DXGI_FORMAT_R8_UNORM texture for all channels of the returned color except for A, which should be set to 1.0f.

L. Spiro

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Use the R value from your DXGI_FORMAT_R8_UNORM texture for all channels of the returned color except for A, which should be set to 1.0f.

L. Spiro

i'm so sorry L.Spiro, i'm a beginner in d3d11, may you be more specific? When i call LoadTexture how can i set the channels as you said?

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As noted in the documentation, you can replicate the D3D9 behavior by using .r to swizzle the data in the shader.

So something like this:

float4 color = float4(textureColor.rrr, 1.0f);

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Now i have errors with the texture sampler, it is only happening with the R8_unorm format.

Here is the result:

And here is the source image:

// Pixel Shader
float4 main_ps( v2p input ) : SV_TARGET
{
float4 l_color0;
l_color0 = g_frostTexture.Sample(SampleType, input.texCoord);
l_color1 = float4( l_color1.rrr, 1.0f);
returnl_color1;
}

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I don’t use Ogre but the error seems apparent: The image is now 4 times as wide and the RGB channels are all the same (so every 3 pixels are grey) and the A channel is white (so every 4th pixel is white).

In other words, something is expecting 1 result but is being fed 4.  For whatever reason it is actually using all 4 results and treating them as separate results.  Instead of combining the RGBA values into one pixel, it is spreading them out over 4 pixels.

That is basically the problem, but I have never seen this and I am not familiar with Ogre, so I can’t tell you where to look.  The first things I would check would be the texture-creation values and the render-target creation values.

L. Spiro

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