Imwrite outputs white image

Hi,

I am trying to save a slice from an image stack using imwrite but it writes blank (white) images. I suspect it is an issue with imwrite assuming a dynamic range of [0 1] while I would like to use []. Is there a way to get around this?

Example code:

 for a=1:10

   imshow(Ibf(:,:,a),[0 1]) %Image displays blank (completely white)
   imshow(Ibf(:,:,a),[])    %Image displays correctly

   imwrite(Ibf(:,:,a),'filename.jpg')); %Output is white images

 end

Note: Ibf is an image stack in grayscale

[DGM]

The problem is an issue of the expected scale. Regardless of class, if the image is properly scaled for its class, then it will both display and write as expected. If you have a floating point image that's improperly-scaled (i.e. not unit-scale), then it won't be written or displayed correctly.

This is almost certainly a consequence of casting an integer-class image as 'double' without scaling it accordingly. Either rescale the floating-point image to unit-scale, or cast it to the class that corresponds to its current scale. If you're going to work with intermediate images in an improperly-scaled state, that's fine, but you'll have to account for it.

https://www.mathworks.com/help/images/convert-image-data-between-classes.html?s_tid=answers_rc2-3_p6_Topic

Answer 1

[Image Analyst]

If Ibf is a normal uint8 RGB image in the range 0-255 then of course saying it should display [0,1] as 0-255 will send 0 to 0 and 1 and anything more than that to 255. What is the class of Ibf? Is it double or uint8? If it's uint8, the imwrite should write out correctly as you have it.