def old_idct(x):
'''dct type 3 in 2D; transform -> image'''
out = np.empty((32, 32, 3), dtype='float32')
for ch in range(3):
out[:, :, ch] = scidct(scidct(x[:, :, ch], type=3,
norm='ortho', axis=0),
type=3, norm='ortho', axis=1)
return np.clip(out, 0, 255).astype('uint8')
def old_dct(x):
'''dct type 2 in 2D; image -> transform'''
out = np.empty((32, 32, 3), dtype='float32')
for ch in range(3):
out[:, :, ch] = scidct(scidct(x[:, :, ch], type=2,
norm='ortho', axis=0),
type=2, norm='ortho', axis=1)
return out
def expand(im, scale_x=2):
'''expand takes a 32x32x3 ndarray image and expands it by DCT/iDCT
scale contrast to full range
does not change colorspace'''
newsize = scale_x * 32
tr = dct(im)
tr_pad = np.zeros((newsize, newsize, 3), dtype='float32')
tr_pad[:32, :32, :] = np.multiply(tr, scale_x)
lo = np.amin(tr[:, :, 0])
# print(lo)
hi = np.amax(tr[:, :, 0])
# print(hi)
tr[:, :, 0] = np.multiply(np.subtract(tr[:, :, 0], lo), 255/(hi - lo))
out = np.empty((newsize, newsize, 3), 'float32')
for ch in range(3):
out[:, :, ch] = scidct(scidct(tr_pad[:, :, ch], type=3, norm='ortho',
axis=0),
type=3, norm='ortho', axis=1)
return np.clip(out, 0, 255).astype('uint8')
def idct(x):
return np.clip(scidct(scidct(x, type=3, norm='ortho', axis=0),
type=3, norm='ortho', axis=1),
0, 255).astype('uint8')
def dct(x):
return scidct(scidct(x, type=2, norm='ortho', axis=1),
type=2, norm='ortho', axis=0)