I want to load a 24 bit bitmap, search for specific colors and change them to other colors. GetPixel and SetPixel is extremely slow but I came up with something else that seems to work, here:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
GetObject(hBmp, sizeof(BITMAP), &bitmap);
DWORD bmpLen = bitmap.bmWidthBytes * bitmap.bmHeight;
BYTE* bmp = new BYTE[bmpLen];
COLORREF cr = 0;
GetBitmapBits(hBmp, bmpLen, bmp);
for (DWORD i = 0; i < bmpLen; i += (bitmap.bmBitsPixel / 8))
CopyMemory(&cr, &bmp[i], sizeof(COLORREF));
// ----> CHANGE COLOR
CopyMemory(&bmp[i], &cr, sizeof(COLORREF));
It seems to work but when I save the bmp array to a binary file the file becomes larger than the original bitmap by about 200 kb which must mean somehow I didn't calculate the bitmap size correctly. What am I doing wrong?
Unsure where the problem is. I mean, there's a potential for corruption with your code on less-than-sizeof(COLORREF) bytes per pixel, but corruption shouldn't increase size unless Windows recalculates a bitmap based on the new bits.
So show your full conversion code, including how you set the bits after color modification.