Comments (3)
Hi @renerichter ! Great to see the interest!
Unfortunately I still haven't implemented automatic calculation of window sizes and overlap to get constant 1.0 "weight" in Merger. It is in the roadmap and I have to admit it has been there for too long! For now, you have to calculate "correct" sizes yourself and/or apply padding like in the examples/2d_overlap_tile.py
.
You could divide the merged data by the number of times each element has been seen in tiles. This would work properly only for boxcar (constant) window: imf = merger.merge(unpad=True, argmax=False) / merger.data_visits[:imsize, :imsize]
I think I will add such normalization as another flag for Merger.merge()
next time I work on the project.
Hope that helps!
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I added #7 and would like to discuss the merging strategy.
Building onto my pull-request the following test-code is applied
Test Code
import numpy as np
from tiler import Tiler,Merger
import matplotlib.pyplot as plt
# %% Test example for online
# parameter
data_shape = [1,256,256]
tile_shape = np.array([1,64,64])
overlap=np.array([0,7,20])
tiler_mode = 'wrap'
windows_supported = ['boxcar', 'triang', 'blackman', 'hamming', 'hann', 'bartlett', 'flattop', 'parzen', 'bohman', 'blackmanharris', 'nuttall', 'barthann', 'overlap-tile']
# image
xy = np.ogrid[0:data_shape[-2],0:data_shape[-1]]
xy = np.sqrt(xy[0]*np.transpose(xy[0])+xy[1]*np.transpose(xy[1]))
im = np.cos(4*xy*np.pi/np.max(xy))[np.newaxis]
merged_images = [im,]
# tile me
tiler = Tiler(data_shape=data_shape, tile_shape=tile_shape,overlap=tuple(overlap),get_padding=True)
im_padded = tiler.pad_outer(im,tiler.pads)
weights_sums = [np.ones(im_padded.shape),]
for mwin in windows_supported:
merger = Merger(tiler,window=mwin)
#Merger.SUPPORTED_WINDOWS == ['boxcar', 'triang', 'blackman', 'hamming', 'hann', 'bartlett', 'flattop', 'parzen', 'bohman', 'blackmanharris', 'nuttall', 'barthann', 'overlap-tile']
for tile_id, tile in tiler(im_padded):
processed_tile = tile # lambda x: x
merger.add(tile_id, processed_tile)
imf = merger.merge(data_orig_shape=data_shape)
merged_images.append(imf)
weights_sums.append(merger.weights_sum)
# plot images
merged_images = np.array(merged_images)[:,0]
fig,ax = plt.subplots(nrows=4,ncols=4,figsize=[14,14])
plt_titles = ['reference',]+windows_supported
axm = ax.flatten()
for m,mim in enumerate(merged_images):
ima = axm[m].imshow(mim,interpolation='None')
axm[m].set_title(plt_titles[m])
plt.suptitle('Resulting Images')
plt.tight_layout()
plt.show()
# plot images
weights_sums = np.array(weights_sums)[:,0]
fig2,ax2 = plt.subplots(nrows=4,ncols=4,figsize=[14,14])
plt_titles = ['reference',]+windows_supported
axm = ax2.flatten()
inv_weights = merger.norm_by_weights((weights_sums[0])[np.newaxis], weights=weights_sums)
inv_weights/= np.max(inv_weights,axis=(-2,-1),keepdims=True)
for m,invm in enumerate(inv_weights):
ima = axm[m].imshow(invm**0.002,interpolation='None')
axm[m].set_title(plt_titles[m])
plt.suptitle('Inverse Weights-maps **0.002 (for display)')
plt.tight_layout()
plt.show()
# differences
for m,mim in enumerate(merged_images):
print(f"All close for window_func={plt_titles[m]}?\t {np.allclose(mim,im[0])}")
The results are:
Resulting Images:
Weights used for reweighting:
Comparison between Reference and re-merged images
All close for window_func=reference? True
All close for window_func=boxcar? True
All close for window_func=triang? TrueM
All close for window_func=blackman? True
All close for window_func=hamming? True
All close for window_func=hann? True
All close for window_func=bartlett? True
All close for window_func=flattop? False
All close for window_func=parzen? True
All close for window_func=bohman? True
All close for window_func=blackmanharris? True
All close for window_func=nuttall? True
All close for window_func=barthann? True
All close for window_func=overlap-tile? False
For the reweighting I interpreted the calculation steps to be like if one would calculate a center-of-mass kind of thing. Hence,
- multiplying each tile with the window
- summing the tiles into the final image
- dividing by the summed weights window-function
could reproduce the wanted normalization of the output. On the other hand, if the window-functions are normed and symmetric than the final division by the weights would just undo the prior weighting of the tiles. Hence I believe I have a thinking error somehow here. What do you think?
PS: Flat-top normalization needs to be fixed...
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Merged #7.
I will close this issue, but please feel free to open new issues/discussions!
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