Images disappearing when compiling with tex4ebook

Question

I am trying to convert an existing book from plain PDF output to ebook format for online publishing (and doing some reformatting in the process, but that's another question).

I have images in the \part page (thanks to @PeterWilson for that). Problem is those images do not appear in tex4ebook output, without any error/warning.

Full (current) header of my book follows:

\documentclass[10pt,ebook,italian,onecolumn,oneside,titlepage,extrafontsizes]{memoir}
\usepackage[italian]{babel}
\usepackage{graphicx}
\usepackage[utf8x]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{ucs}
\usepackage{makeidx}
\usepackage{quotmark}
\newcommand{\gqt}[1]{\tqt{\scshape #1}}
\newcommand{\stars}{\begin{center} * * *\\ \end{center}}
%
\makeatletter
\def\@partimage{}
\newcommand{\partimage}[2][]{\gdef\@partimage{\includegraphics[#1]{#2}}}
\renewcommand{\printparttitle}[1]{\parttitlefont #1\vfil\@partimage\vfil\gdef\@partimage{}}
\makeatother
%
\setlength\cftpartnumwidth{2em}
%
\author{Mauro Condarelli}
\title{Cronache della Nuova Terra}
\begin{document}
%
\frontmatter
\maketitle
%
\mainmatter
\chapterstyle{companion}
%\book{Cronache della Nuova Terra}
\tableofcontents
%
\partimage[width=210pt]{old_mage.jpg}
\part{In cerca di un Mondo Nuovo}
%
%
\chapter{La Missione}
%
%scene: 'Prologo I'

La Pianta non era certo imponente, somigliava a una verza troppo cresciuta, alta quasi un metro e mezzo e larga altrettanto, grandi foglie verde pallido sormontavano un tronco corto e tozzo dal quale partiva un robusto peduncolo che portava a una grossa zucca adagiata sulla sabbia pulita.\par
...
%end scene
%
%end chapter
%

\backmatter
\appendix
%
%
\end{document}

Problem, as said, is image (old-mage.jpg, in this case) simply vanishes leaving no visible trace.

I'm using a plain: tex4ebook -c tex4book.cfg Cronache_della_Nuova_Terra.tex to compile; contents of tex4book.cfg follows:

\Preamble{xhtml}   
\CoverMetadata{thano.jpg}
\Configure{AddCss}{blitz-lite.css}
\DeclareGraphicsExtensions{.svg,.png,.jpg,.pdf}
\begin{document}
\EndPreamble

Any hint welcome

Answer 1

tex4ht redefines all sectioning commands, in order to provide a uniform configurable interface for all LaTeX classes. So the \printparttitle command is not used in tex4ht. Instead, the image can be printed in configuration for \part. Try the following configuration file:

\Preamble{xhtml}
\CoverMetadata{thano.jpg}
\Configure{AddCss}{blitz-lite.css}
\makeatletter
\Configure{part}
{}{}
{\ifvmode\IgnorePar\fi\EndP\HCode{<h1 class="partHead"><span class="titlemark">}\partname \ \thepart \HCode{</span>}}
{\HCode{</h1>\Hnewline<aside class="partimage">}\@partimage\HCode{</aside>}\IgnoreIndent\par\OpfRegisterFile}
\makeatother
\Css{.partimage{margin:0 auto;text-align:center;}}
\Css{.partimage img{max-width:100\%;}}
\Css{.partHead .titlemark{display:block;}}
\DeclareGraphicsExtensions{.svg,.png,.jpg,.pdf}
\begin{document}
\EndPreamble

The most important part is in \Configure{part} from the manual:

\Configure{unit} {top} {bottom} {before-title} {after-title}

This command determines the content to be inserted at the mentioned locations of the specified units.

\Configure{chapter}
{\HCode{<div class="chapter">}}  {\HCode{</div>}}
{\HCode{<h2 class="chapterHead">}\chaptername
    ~\thechapter\HCode{<br />}}
{\HCode{</h2>}}

So we insert the image in the top insertion:

 \ifvmode\IgnorePar\fi\EndP\HCode{<aside class="partimage">}\@partimage\HCode{</aside>}

The \ifvmode\IgnorePar\fi\EndP is necessary to get the paragraphs right, \HCode{<aside class="partimage">}\@partimage\HCode{</aside>} then prints the image inside <aside class="partimage"> element. This enables us to style it using CSS styles, as can be seen in the \Css commands.

The \OpfRegisterFile command is necessary for a correct page sequence. This command is provided by tex4ebook and registers current HTML file to a page sequence. The page with part title would be displayed at the end of file otherwise.

This is the result: