Find an exe file - magick.exe, then make two copies of it with name "covert.exe" "imgconvert.exe" in the same folder. Then run your command again.
You can find the file in the folder of ImageMagick, which is "C:\Program Files (x86)\ImageMagick-7.0.6-Q16" for me.
You get this error because the new version of ImageMagick changed the name of "covert.exe" to "magick.exe" while the standalone package didn't know that. For the file "imgcovert.exe", it maybe needed for windows user for some standalone text file to avoid another convert.exe in windows.
As is explained in How do I draw shapes inside a tikz node? pics can be used for defining new objects. My main problem using pics is how to place where you want because they aren't nodes and positioning them is not so easy.
Following code shows how to define EDFA block.
EDFA/.pic={
\begin{scope}[scale=.5]
\draw (-1,0) coordinate (in) -- (-1,1) -- (1,0) coordinate (out) -- (-1,-1) -- cycle;
\node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
\end{scope}
In this case, coordinate (-1,0) will act as west anchor and 1,0 as east. Both point will have an special name for further reference. Every pic is placed according its own origin (0,0). You can use Claudio's answer to Anchoring TiKZ pics for better positioning.
As your example was simple, I'd prefer to star with EDFA and place Source and Sink after it.
\documentclass[]{article}
% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning
\begin{document}
\tikzset{%
EDFA/.pic={
\begin{scope}[scale=.5]
\draw (-1,0) coordinate (in) -- (-1,1) -- (1,0) coordinate (out) -- (-1,-1) -- cycle;
\node[anchor=north,inner sep=2pt] at (0,-1) {$1$};
\end{scope}
}
}
\begin{tikzpicture}[
block/.style={draw},
]
\draw pic (edfa) {EDFA};
\node[block, left=of edfain] (source) {Source};
\node[block, right= of edfaout] (sink) {Sink};
\draw[->] (source) -- (edfain);
\draw[->] (edfaout) -- (sink);
\end{tikzpicture}
\end{document}
I understand that your components are more complex than EDFA because for this particular case an isosceles triangle node with a label will do the work and it can be used as a node and not as a pic:
\documentclass[]{article}
% tikz
\usepackage{tikz}
\usetikzlibrary{positioning} %relative positioning
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}[
block/.style={draw},
edfa/.style={isosceles triangle, minimum width=1cm,
draw, anchor=west, isosceles triangle stretches,
minimum height=1cm, label=-80:#1}
]
\node[block] (source) {Source};
\node[edfa=1, right=of source] (edfa) {};
\node[block, right= of edfa] (sink) {Sink};
\draw[->] (source) -- (edfa);
\draw[->] (edfa) -- (sink);
\end{tikzpicture}
\end{document}
Best Answer
PDF's can and will have transparency since PDF 1.4. https://en.wikipedia.org/wiki/PDF#Transparency
Your code generates a PDF with transparent background(Correction: No background). Apparently, your export settings of Adobe Acrobat makes your PNG white.
I compile your code, and use:
to create this PNG:
(Here shown viewed in Mac preview)
convertis from ImageMagick: https://imagemagick.org (free for all platforms)