Yet simple tool to paste images into markdown files
You are editing a markdown file and have an image on the clipboard and want to paste it into the document as the text . Instead of first copying it to that directory, you want to do it with a single <leader>p key press in Vim. So it hooks <leader>p, checks if you are editing a Markdown file, saves the image from the clipboard to the location img/image1.png, and inserts  into the file.
By default, the location of the saved file (img/image1.png) and the in-text reference ( are identical. You can change this behavior by specyfing an absolute path to save the file (let g:mdip_imgdir_absolute = /absolute/path/to/imgdir on linux) and a different path for in-text references (let g:mdip_imdir_intext = /relative/path/to/imgdir on linux).
Using Vundle
Plugin 'ferrine/md-img-paste.vim'
Add to .vimrc
autocmd FileType markdown nmap <buffer><silent> <leader>p :call mdip#MarkdownClipboardImage()<CR>
" there are some defaults for image directory and image name, you can change them
" let g:mdip_imgdir = 'img'
" let g:mdip_imgname = 'image'
This plugin gets clipboard content by running the xclip command.
install xclip first.
I'm not yet perfect at writing vim plugins but I managed to do it. Thanks to Karl Yngve Lervåg and Rich for help on vi.stackexchange.com where they proposed a solution for my use case.