Show whole of image on screen in any orientation I'm using Firefox version 44.0.2 on the Galaxy Note 4. I cannot zoom out enough to view the whole of images on the screen - so I have to scroll to get a glimpse. 

It seems the image is zoomed to fit the height of the phone in portrait mode and zoomed to the width with the phone in landscape mode. End result is I cannot ever see the whole image at once.

For testing I used this image.

Attempted solutions: 


I have tried to change a few of the zoom-settings such as browser.zoom.full, toolkit.zoomManager.zoomValues, and zoom.minPercent in about:config, to no avail. 
I have also tried disabling all add-ons.
With an image (example) with 16/9 aspect ratio and the add-on "Full screen mobile", I can actually see the whole image.


So how to make it show the whole image on the screen, no matter how you hold the phone?

In general it would be nice to have kind of indefinite zoom in and zoom out on all content on the web - both images and web pages.
Looking to do this?
(Click image to enlarge)

Perhaps this?

Turned out that the config browser.enable_automatic_image_resizing controls the behavior you want to change.

True: When viewing an image not in a web page, the image will be resized to fit in the browser window if it is too large for the browser window.
False (default in Firefox for Android): Images are always shown in their real size.

Toggle that setting to true in config editor.
For users new to the Firefox config entries: type about:config in URL bar, agree for whatever it asks for, type browser.enable_automatic_image_resizing in search field and toggle the entry to true.
There is more here. You can search for the config entry browser.enable_click_image_resizing. Toggle it. Now, the effects are identical to previous config entry except that whenever you would single tap on the image, its original size would load. When you tap on original size, the image will be re-sized to fit the page width. Convenient, I suppose.
One more. The config entry layout.css.devPixelsPerPx can also achieve what the first config entry can, but it requires efforts to pin pinpoint the value specific to your device and it would mess up with view of your pages. Nonetheless, it can do the job.
Note: Tested on Firefox for Android v44.0.2