private void loadSizes() {
        int mipWidth = width;
        int mipHeight = height;

        sizes = new int[mipMapCount];
        int outBpp = pixelFormat.getBitsPerPixel();
        for (int i = 0; i < mipMapCount; i++) {
            int size;
            if (compressed) {
                size = ((mipWidth + 3) / 4) * ((mipHeight + 3) / 4) * outBpp * 2;
            } else {
                size = mipWidth * mipHeight * outBpp / 8;
            }

            sizes[i] = ((size + 3) / 4) * 4;

            mipWidth = Math.max(mipWidth / 2, 1);
            mipHeight = Math.max(mipHeight / 2, 1);
        }
    }
Computes the sizes of each mipmap level in bytes, and stores it in sizes_[].
jme3-core/src/plugins/java/com/jme3/texture/plugins/DDSLoader.java