Imageio flips black and white

Question

I have a binary black and white image as a .tif file. I do this

image = imageio.imread(path)
print ' Min and max ', image.min(), image.max(), image.shape, type(image[0,0])
imageio.imsave(path, image)

Which prints

Min and max  0 255 (1024, 1024) <type 'numpy.uint8'>

However, after I run that, black and white colors have reversed. What is going on?

When I try this command

identify -verbose 6hr-001-DIC.tif

on the pre-processed image, I see

tiff:photometric: min-is-white

But after I run the python code, it shows tiff:photometric: min-is-black

So how can I address this, i.e. make sure it's not getting changed?

TIF supports *"min is black"* or *"min is white"* in its *Photometric Interpretation* tag. It may be that Python `imageio` does not respect that. Try using `tiffump` on your input and output files, or **ImageMagick** `identify -verbose image.tif` to check. — Mark Setchell, Aug 20 '18 at 22:10
You can also set the tag yourself with `tiffset -s 262 0|1 image.tif` — Mark Setchell, Aug 20 '18 at 22:15
In my longer comment above, read *"respect"* as *"respect or preserve"*. — Mark Setchell, Aug 20 '18 at 22:16
Thanks, that was a good catch. I updated my original question. How can I make sure imageio respects this? — Baron Yugovich, Aug 20 '18 at 22:17
Not sure. At least we know the problem. It seems you can set it on writing (see `photometric` here https://imageio.readthedocs.io/en/stable/format_tiff.html#tiff I am not sure how you get the current setting on read though in order to preserve it. — Mark Setchell, Aug 20 '18 at 22:25

score 3 · Accepted Answer · answered Aug 21 '18 at 01:07

As @Mark Stechell pointed you need to use the photometric metadata field. First make sure you have installed tifffile. For the sake of demonstration I am using the marbles image in grayscale. Now the code:

import imageio

image = imageio.imread('gmarbles.tif')
print(' Min and max ', image.min(), image.max(), image.shape, type(image[0, 0]))

image.meta['photometric'] = 'miniswhite'
imageio.imsave('white.tif', image)

or alternative set to 'minisblack':

Imageio flips black and white

1 Answers1