Convert an image format from 32FC1 to 16UC1

Question

I need to encode an image in 16UC1 format, but I receive the error: cv_bridge.core.CvBridgeError:encoding specified as 16UC1, but image has incompatible type 32FC1

I tried to use skimage function img_as_uint but since my image values are not between -1 and 1 it doesn't work. i also tried to "normalize" my values by dividing all of them by the value obtained from np.amax, but using the skimage function only returns a blank image.

Is there a way of achieving this conversion?

This is the original 32FC1 image

Please provide some code so we can diagnose your problem :) – nathancy Dec 13 '19 at 01:42 — nathancy, Dec 13 '19 at 01:42

shortcipher3 · Accepted Answer · 2019-12-18T16:32:39.230

1

With numpy you should be able to:

import numpy as np
img = np.random.normal(0, 1, (300, 300, 3)).astype(np.float32) # simulated image
uimg = img.astype(np.uint16)

You probably will first want to do some kind of normalization if it isn't already in an unsigned range. Probably something like:

img_normalized = (img-img.min())/(img.max()-img.min())*256**2

But your normalization strategy will depend on what you want to accomplish.

Thanks for sharing an image. I can visualize as follows:

import numpy as np
import matplotlib.pyplot as plt

arr = np.load('32FC1_image.npz')
img = arr['arr_0']
img = np.squeeze(img) # this gets rid of the extra dimensions that are causing matplotlib to not recognize it as an image, the extra dimensions also may be causing your problems
img_normalized = (img-img.min())/(img.max()-img.min())*256**2
img_normalized = img_normalized.astype(np.uint16)
plt.imshow(img_normalized)

Try using the normalized 16 bit image.

edited Dec 18 '19 at 16:32

answered Dec 13 '19 at 04:26

shortcipher3

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Doing this returns a black image when using `cv_bridge ` – Sebastián Mayorga Dec 13 '19 at 22:59
This is not surprising, it probably has to do with the normalization, probably means that there is a large value throwing for the colormap being applied. Can you provide an example image? You can save the original `32FC1` with `np.savez('myfile.npz', myimg)` then upload. – shortcipher3 Dec 14 '19 at 02:53
I have the .npz file but I dont know how to upload it – Sebastián Mayorga Dec 15 '19 at 19:42
You could try this service and share the link: https://www.filedropper.com/ – shortcipher3 Dec 16 '19 at 03:41
I added the link – Sebastián Mayorga Dec 17 '19 at 02:07
I can't open with `np.load('myfile.npz')`, are you able to load? – shortcipher3 Dec 17 '19 at 13:29
It is working know, just had to add `plt.show()` at the end – Sebastián Mayorga Dec 21 '19 at 16:15

Convert an image format from 32FC1 to 16UC1

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