Images with no color channel!

[bhashemian]

Describe the bug
When using cuCIM to load TIFF files that does not have color channel (a grayscale 2D image), no error is thrown and instead the values will be repeated to create an RGBA image, representing the grayscale image. This may cause confusion, like here: Project-MONAI/MONAI#3858

Steps/Code to reproduce bug

import numpy as np                                                                                                                                                                                                                           
from skimage import io    
from cucim import CuImage

image_path = "test.tif"
x = np.random.randint(low=0, high=256, size=(128,128), dtype=np.uint8)
io.imsave(image_path, x) 

img = np.array(CuImage(image_path).read_region())
print(f"{img.shape = }")
print(f"{img[0, 0, :] = }")

img.shape = (128, 128, 4)
img[0, 0, :] = array([121, 121, 121, 255], dtype=uint8)

[bhashemian]

@gigony is there any update on this? thanks

[gigony]

@drbeh we would eventually need to support multi-band and other data types

• [FEA] Supporting multi bands (multi-channel) images for geospatial (remote sensing) and microscopy #33

Currently, if the image is not RAW/LZW/JPEG/JPEG2000-compressed tiled/multi-resolution RGB images, it delegates its processing to libtiff's TIFFRGBAImageGet() method that creates a 4-channel RGBA array.

What would you suggest until we support single-channel image data? Maybe raising a warning message would be one we can do?

[bhashemian]

Thank you, @gigony! Raising an error would satisfy the purpose of this open issue. Currently, we don't have any need for single-channel images in digital pathology but it might be a good feature to have.