put attached file into ~/picture.png
start emacs -Q
evaluate
(insert-image (create-image "~/picture.png"))
The image is scrambled.  With imagemagick the image displays correctly
(insert-image (create-image "~/picture.png" 'imagemagick))
Of course, not all png images are scrambled.  So it seems to be a bug
that is triggered only by certain png images.


In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.18.9)
 of 2018-05-29 built on regnitz
Windowing system distributor 'The X.Org Foundation', version 11.0.11804000
System Description:	Ubuntu 16.04.6 LTS

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LCMS2

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.utf8
  value of $XMODIFIERS: 
  locale-coding-system: utf-8-unix

Major mode: Fundamental