latex, replace `'pixelsize' by more precise 'pxunit'` name

doc/config.rst

@@ -1601,12 +1601,13 @@ These options influence LaTeX output. See further :doc:`latex`.
      ``'pointsize'``
         Point size option of the document class (``'10pt'``, ``'11pt'`` or
         ``'12pt'``), default ``'10pt'``.
-     ``'pixelsize'``
-        px unit size, default ``'49336sp'`` which achieves ``96px=1in`` (as
-        ``1in = 72.27*65536 = 4736286.72sp``, and all dimensions in TeX are
-        internally integer multiples of ``sp``). To obtain for example
-        ``100px=1in``, one can use ``'0.01in'`` but it is more precise to issue
-        ``'pixelsize':'47363sp',``.
+     ``'pxunit'``
+        the value of the ``px`` when used in image attributes ``width`` and
+        ``height``. The default value is ``'49336sp'`` which achieves
+        ``96px=1in`` (``1in = 72.27*65536 = 4736286.72sp``, and all dimensions
+        in TeX are internally integer multiples of ``sp``). To obtain for
+        example ``100px=1in``, one can use ``'0.01in'`` but it is more precise
+        to use ``'47363sp'``.
 
         .. versionadded:: 1.5
      ``'babel'``

sphinx/writers/latex.py

@@ -37,7 +37,7 @@ HEADER = r'''%% Generated by Sphinx.
 \documentclass[%(papersize)s,%(pointsize)s%(classoptions)s]{%(wrapperclass)s}
 \ifdefined\pdfpxdimen
    \let\sphinxpxdimen\pdfpxdimen\else\newdimen\sphinxpxdimen
-\fi \sphinxpxdimen=%(pixelsize)s\relax
+\fi \sphinxpxdimen=%(pxunit)s\relax
 \usepackage{iftex}
 %(passoptionstopackages)s
 %(inputenc)s
@@ -302,7 +302,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
     default_elements = {
         'papersize':       'letterpaper',
         'pointsize':       '10pt',
-        'pixelsize':       '49336sp',
+        'pxunit':          '49336sp',
         'classoptions':    '',
         'extraclassoptions': '',
         'passoptionstopackages': '',