Optimising CImage Rotation

I'm attempting to optimise some CImage manipulations by using GetBits() rather than the time consuming GetPixel() SetPixel() method.

These variables are defined (with CImage *i as a parameter);

int height = i->GetWidth(); //width and height swapped for 90 degree rotation

    int width = i->GetHeight();
    int bpp = i->GetBPP();
    int pitch1 = i->GetPitch();

    int hwidth = width / 2;
    int hheight = height / 2;

    double sinma = sin(1.57079633f); //90 degree rotation
    double cosma = cos(1.57079633f);

    CImage *dest = new CImage();
    dest->Create(width, height, bpp);
int pitch2 = dest->GetPitch();

The non-optimised code works fine:

for (int x = 0; x < width; x++) 
    {
        for (int y = 0; y < height; y++) 
        {
            int yt = x - hwidth;
            int xt = y - hheight;

            int ys = (int)round((cosma * xt - sinma * yt) + hwidth); //get rotated pixel
            int xs = (int)round((sinma * xt + cosma * yt) + hheight);

            if (xs >= 0 && xs < height && ys >= 0 && ys < width) {
                // set target pixel (x,y) to color at (xs,ys) 
                dest->SetPixel(x, y, i->GetPixel(xs, ys));
            }
            else {
                // set target pixel (x,y) to some default background
                COLORREF pixel = RGB(0, 0, 0);
                dest->SetPixel(x, y, pixel);
            }
        }
    }

This produces a perfect result

but a weird result occurs when optimising:

for (int x = 0; x < width; x++) 
{
    for (int y = 0; y < height; y++) 
    {

        int yt = x - hwidth;
        int xt = y - hheight;

        int ys = (int)round((cosma * xt - sinma * yt) + hwidth);
        int xs = (int)round((sinma * xt + cosma * yt) + hheight);

        if (xs >= 0 && xs < height && ys >= 0 && ys < width) {
            // set target pixel (x,y) to color at (xs,ys) 
            //dest->SetPixel(x, y, i->GetPixel(xs, ys));

            lAdrs2 = x * pitch2 + y * 3; // set target pixel (x,y)
            lAdrs1 = ys * pitch1 + xs * 3; // to color at (xs,ys) 

            bRed = *(pInImage + lAdrs1);
            bGreen = *(pInImage + lAdrs1 + 1);
            bBlue = *(pInImage + lAdrs1 + 2);

            *(pOutImage + lAdrs2) = static_cast<BYTE>(bRed);
            *(pOutImage + lAdrs2 + 1) = static_cast<BYTE>(bGreen);
            *(pOutImage + lAdrs2 + 2) = static_cast<BYTE>(bBlue);
        }

    }
}

When the angle is set to 0, this happens

Any reason that this occurs when accessing the bits manually?