从float数组在Visual C ++中创建灰度图像

Question

I have an array of grayscale pixel values (floats as a fraction of 1) that I need to display, and then possibly save. The values just came from computations, so I have no libraries currently installed or anything. I've been trying to figure out the CImage libraries, but can't make much sense of what I need to do to visualize this data. Any help would be appreciated!

Thank you.

Answer 1

One possible approach which I've used with some success is to take D3DX's texture functions to create a Direct3D texture and fill it. There is some overhead in starting up D3D, but it provides you with multi-thread-able texture creation and built-in-ish viewing, as well as saving to files without much more fuss.

If you're not interested in using D3D(X), some of the specifics here won't be useful, but the generator should help figure out how to output data for any other library.

For example, assuming an existing D3D9 device pDevice and a noise generator (or other texture data source) pGen :

IDirect3DTexture9 * pTexture = nullptr;
D3DXCreateTexture(pDevice, 255, 255, 0, 0, D3DFMT_R8G8B8, D3DPOOL_DEFAULT, &pTexture);
D3DXFillTexture(pTexture, &texFill, pGen);
D3DXSaveTexture("texture.png", D3DXIFF_PNG, pTexture, NULL);

The generator function:

VOID WINAPI texFill(
    D3DXVECTOR4* pOut, 
    CONST D3DXVECTOR2* pTexCoord, 
    CONST D3DXVECTOR2* pTexelSize, 
    LPVOID pData,  
) {
    // For a prefilled array:
    float * pArray = (float *)pData;
    float initial = pArray[(pTexCoord->y*255)+pTexCoord->x];

    // For a generator object:
    Generator * pGen = (Generator*)pData; // passed in as the third param to fill
    float initial = pGen->GetPixel(pTexCoord->x, pTexCoord->y);

    pOut->x = pOut->y = pOut->z = (initial * 255);
    pOut->w = 255; // set alpha to opaque
}

• D3DXCreateTexture: http://msdn.microsoft.com/en-us/library/windows/desktop/bb172800%28v=vs.85%29.aspx
• D3DXFillTexture: http://msdn.microsoft.com/en-us/library/windows/desktop/bb172833(v=vs.85).aspx
• D3DXSaveTextureToFile: http://msdn.microsoft.com/en-us/library/windows/desktop/bb205433(v=vs.85).aspx

Corresponding functions are available for volume/3D textures. As they are already set up for D3D, you can simply render the texture to a flat quad to view, or use as a source in whatever graphical application you may want.

So long as your generator is thread-safe, you can run the create/fill/save in one thread per texture, and generate multiple slices or frames simultaneously.

Answer 2

I found that the best solution for this problem was to use the SFML library (www.sfml-dev.org). Very simple to use, but must be compiled from source if you want to use it with VS2010.

Answer 3

You can use the PNM image format without any libraries whatsoever. (The format itself is trivial). However it's pretty archaic and you'll have to have an image viewer that supports it. IvanView, for example, supports it on Windows.