Page background with transparency colours

Question

Take a look at this page layout

I would like to achieve a result like the above in the booklet I am writing. Here is what I have so far

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage[lmargin=0.7cm, rmargin=1cm, vmargin=1.5cm]{geometry}
\renewcommand{\qedsymbol}{$\blacklozenge$}
\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{eulervm}
\usepackage{esint}

\usepackage{fontawesome}
\renewcommand{\thefootnote}{\faDatabase}

\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\lhead{Mathematical Analysis ... }
\chead{... \textit{A collection of problems}} 
\rhead{Version 6}
\cfoot{Page \@ \thepage \@ of 24}
\lfoot{Typesetting \LaTeX }
\rfoot{\textbf{Editor:} Tolaso J. Kos}
\renewcommand{\headrulewidth}{2pt}
\renewcommand{\footrulewidth}{0.5pt}

\usepackage{tcolorbox}


\usepackage{tikz} 
\usetikzlibrary{intersections,backgrounds}
\usepackage{pgfplots}
\usepgfplotslibrary{colormaps}

\usepackage[shortlabels]{enumitem}
\usepackage{bigints}
\usepackage{cancel}
\usepackage{multicol}
\setlength{\parskip}{\baselineskip}%
\setlength{\parindent}{0.5pt}%
\usepackage{xcolor}

%definition of dark red
\definecolor{DarkBlue}{RGB}{102, 153, 255}
\definecolor{LightBlue}{RGB}{51, 102, 255}
\usepackage{afterpage}

\makeatletter
% Macro \changepagecolor has the same syntax as \pagecolor or \color
% with an optional argument and a mandatory argument.
\newcommand*{\changepagecolor}{%
  \@ifnextchar[\@changepagecolor@i\@changepagecolor@ii
}
% Case: \changepagecolor[...]{...}
\def\@changepagecolor@i[#1]#2{%
  \@changepagecolor@do{[{#1}]{#2}}%
}
% Case: \changepagecolor{...}
\newcommand*{\@changepagecolor@ii}[1]{%
  \@changepagecolor@do{{#1}}%
}
\newcommand*{\@changepagecolor@do}[1]{%
  % Fill the remaining space with a colored rule
  \begingroup
    \offinterlineskip
    \hbox to 0pt{%
      \kern-\paperwidth
      \vtop to 0pt{%
        \color#1%
        \hrule width 5\paperwidth height \paperheight
        \vss
      }%
      \hss
    }%
  \endgroup
}
\makeatother

\usepackage{pagecolor}
\usepackage{atbegshi} % for '\AtBeginShipout' macro
% Make page color "light red" *after* page 2
\AtBeginShipout{\ifnum\value{page}=1\pagecolor{white}\fi}

%the title of this project

\newcommand{\mytitle}{\textbf{Mathematical Analysis}}
\newcommand{\mydescription}{\textbf{A collection of problems}}
\newcommand{\mytiny}{\textbf{Real \& Complex Analysis - General Topology - Multivariable Calculus  - Integrals and Series}}

%font for name

\usepackage{pbsi}


\begin{document}
\begin{flushleft}

\thispagestyle{empty}

\pagecolor{DarkBlue}

\begin{center}
{\Huge \mytitle} 

{\Large \mydescription}

{\tiny \mytiny}
\end{center}

\topskip0pt
\vspace*{\fill}

\changepagecolor{LightBlue}

\begin{multicols}{2}
    \begin{tikzpicture}
    \begin{axis}[
    view={120}{40},
    grid=major,
    xmin=-4,xmax=4,
    ymin=-4,ymax=4,
    zmin=-1,zmax=10,
    enlargelimits=upper,
    colormap/bone,
    trig format plots=rad,
    ]
    \addplot3 [ surf, domain=-4:4, domain y=-4:4,
    samples=20, samples y=20,
    variable=\u, variable y=\v,
    point meta=u*v ]
    ( {u}, {v}, {cos(u) + cos(v)} );
    \end{axis}
    \end{tikzpicture}

    \begin{tikzpicture}
    %axis 
    \draw (-.5,0) -- (6.5,0);  

    %curve  
    \draw[yshift=1cm,name path=curve] (-.5,0) %vertically shiftable
    to[out=70,in=180] (.7,1.5)
    to[out=0,in=180] (2,.5)
    to[out=0,in=180] (4.5,2.5)
    to[out=0,in=160] (6.5,1);

    %rectangles
    \begin{scope}[on background layer]
    \foreach \x in {0,1,2,3, 4,5}{
        \path[name path=line \x] (\x,0) -- (\x,4);
        \path[name intersections={of=curve and line \x, by={isect \x}}];    
        \draw[fill=gray!50] (isect \x) rectangle (\x+1,0);
        \draw[fill] (isect \x) circle [radius=2pt];
    }
    \end{scope}    
    \end{tikzpicture}
\end{multicols}
\vspace*{\fill}


\begin{center}

    {\Huge {\color{white}{Version 6 }}}
\end{center}

\vfill


\begin{center}
    {\Huge \textbf{\textbsi{Tolaso J. Kos}}}
\end{center}

\end{flushleft}
\end{document}

and produces

which is not that bad . But I would like to have a result like the above. I have read some topics here in TeX SE but I find it quite complicated. I would really appreciate your help.

Answer 1

Just a starting point, from Titlepage with tikz:

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{calc,positioning, shadings}% [0]

\begin{document}
\begin{titlepage}
\begin{tikzpicture}[overlay,remember picture]
    % set a new origin [1]
    \coordinate (O) at (current page.south west);
    % bg
    \fill [left color=orange!60!yellow, right color=red!50!black] 
        (current page.south west) rectangle (current page.north east) ;
    % inset; position coordinates
    \coordinate (A) at ($(O)+(0.2\paperwidth,0.7\paperheight)$);
    \coordinate (B) at ($(O)+(0.2\paperwidth,0.3\paperheight)$);
    % maybe you need to do tricks if you want best color merging
    % note that I store the position of the rigth-lower point of the inset
    \fill [red!60!black, ] 
        (A) rectangle ($(B)+(0.6\paperwidth,0)$) coordinate(C);
    % the last coordinate is the point reached horizontally from A and 
    % vertically from C 
    \draw[white] (C) -- (B) -- (A) -- (A -| C);
    % next node will be midway between A and C, anchored at the center
    \node at ($(A)!0.5!(C)$) [%
        anchor = center,
        ] {\includegraphics[width=5cm]{example-image}};
    % white framed box
    \node at (current page.south) [%
        draw=red,
        inner sep=15pt,
        fill=white,
        above=5cm,
        font=\sffamily\bfseries\Huge
    ] {The book title};
\end{tikzpicture}
\end{titlepage}
\end{document}

...which you can change to adapt to your style, I think, quite easily.