dwt.cpp

void DWT::transform1d(float *src, int length, int step)
{
	float *tmp = new float[length];
	float W = 1/sqrt(2.0f);
	for (int len = length/2; len >= PREVIEW; len /= 2) {
		for (int i = 0; i < len; i++) {
			float c = src[i*2*step];
			float w = src[(i*2+1)*step];
			tmp[i] = (c+w)*W;
			tmp[i+len] = (c-w)*W;
		}
		for (int i = 0; i < len*2; i++)
			src[i*step] = tmp[i];
	}
	delete[] tmp;
}

void DWT::untransform1d(float *src, int length, int step)
{
	float *tmp = new float[length];
	float W = 1/sqrt(2.0f);
	for (int len = PREVIEW; len < length; len *= 2) {
		for (int i = 0; i < len; i++) {
			float c = src[i*step];
			float w = src[(i+len)*step];
			tmp[i*2] = (c+w)*W;
			tmp[i*2+1] = (c-w)*W;
		}
		for (int i = 0; i < len*2; i++)
			src[i*step] = tmp[i];
	}
	delete[] tmp;
}

void DWT::transform()
{
	for (int i = 0; i < height; i++)
		transform1d(coeff + i * width, width, 1);

	for (int i = 0; i < width; i++)
		transform1d(coeff + i, height, width);
}

void DWT::untrasform()
{
	for (int i = 0; i < height; i++)
		untransform1d(coeff + i * width, width, 1);

	for (int i = 0; i < width; i++)
		untransform1d(coeff + i, height, width);
}