def test_output(image, jpeg_quality=50, rounding_approximation=None):
jpg = DJPG(rounding_approximation=rounding_approximation, rounding_approximation_steps=5)
print(jpg)
batch_x = np.expand_dims(image, 0)
batch_y = jpg.process(batch_x / 255, jpeg_quality)
n_images = batch_x.shape[0]
batch_j = np.zeros_like(batch_x)
for n in range(n_images):
io.imwrite('/tmp/patch_{}.jpg'.format(n), (batch_x[n].squeeze()).astype(np.uint8), quality=jpeg_quality)
batch_j[n] = io.imread('/tmp/patch_{}.jpg'.format(n))
for n in range(n_images):
plt.subplot(n_images, 3, 1 + n*3)
plotting.quickshow(batch_x[n].squeeze() / np.max(np.abs(batch_x)), 'Input')
plt.subplot(n_images, 3, 2 + n*3)
plotting.quickshow(batch_y[n].squeeze() / np.max(np.abs(batch_y)), 'dJPEG Model')
plt.subplot(n_images, 3, 3 + n*3)
plotting.quickshow(batch_j[n].squeeze() / np.max(np.abs(batch_j)), 'libJPG Codec')
plt.show()
def test_quality(image, rounding_approximation=None, n_quality_levels=91):
jpg = DJPG(rounding_approximation=rounding_approximation,
rounding_approximation_steps=5)
print(jpg)
batch_x = np.expand_dims(image[0:1024, 0:1024, :], 0)
psnrs_y, psnrs_j = [], []
quality_levels = np.unique(
np.round(np.linspace(10, 100,
n_quality_levels)).astype(np.int32)).tolist()
print('Using quality levels: {}'.format(quality_levels))
for jpeg_quality in quality_levels:
batch_y = jpg.process(batch_x / 255, jpeg_quality)
batch_y = np.round(255 * batch_y) / 255
io.imwrite('/tmp/patch.jpg', (batch_x.squeeze()).astype(np.uint8),
quality=jpeg_quality,
subsampling='4:4:4')
batch_j = io.imread('/tmp/patch.jpg')
psnrs_y.append(
compare_psnr(batch_x.squeeze(), 255 * batch_y.squeeze(), 255))
psnrs_j.append(compare_psnr(batch_x.squeeze(), batch_j.squeeze(), 255))
# Plot
plt.figure(figsize=(6, 6))
plt.plot(psnrs_y, psnrs_j, 'bo', alpha=0.25)
plt.plot([30, 50], [30, 50], 'k:')
plt.xlabel('PSNR for dJPEG')
plt.ylabel('PSNR for libJPEG')
plt.xlim([30, 60])
plt.ylim([30, 50])
if rounding_approximation is None:
plt.title('dJPEG vs libJPEG quality (with standard rounding)'.format(
rounding_approximation))
else:
plt.title('dJPEG vs libJPEG quality (with {} rounding approx.)'.format(
rounding_approximation))
for i, q in enumerate(quality_levels):
if q % 10 == 0:
plt.plot(psnrs_y[i], psnrs_j[i], 'ko')
plt.text(psnrs_y[i] + 1, psnrs_j[i] - 0.25, 'Q{:02d}'.format(q))
plt.show()