For IM v7, I suggest you use "magick", not "convert" or "magick convert".
no encode delegate for this image format
This means IM couldn't find a delegate to encode (ie write) the format you want, in this case PNG or JPEG.
So I suspect you didn't build IM with those delegates, eg libpng.
What does "magick version" say? It should be something like:
Code: Select all
Version: ImageMagick 7.0.7-28 Q16 x64 2018-03-25 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC
Visual C++: 180040629
Features: Cipher DPC HDRI Modules OpenMP
Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr openexr pangocairo png ps raw rsvg tiff webp xml zlib
If "Delegates (built-in)" doesn't include png and jpeg, then that's the problem. The solution is to build those libraries first, then rebuild IM.