This jpg file (from photo dated 25 October 2022) posted to the Wikipedia page
on the Dendera Zodiac represents a significant improvement to previous images
available on-line, much sharper, though dimly lit, 72 dpi 60224 unique colors
(cf. dend-zod-1.png, 3.27 MB, 1179 x 1182 pixels, 96 dpi 286533 unique colors):

Wikimedia Commons - Dendera Zodiac, 3,009 x 2,896 pixels, 4.78 MB:
https://upload.wikimedia.org/wikipedia/commons/5/59/Zodiaque_de_Dend%C3%A9ra_-_Mus%C3%A9e_du_Louvre_Antiquit%C3%A9s_Egyptiennes_D_38_%3B_E_13482.jpg

Using freeware RawTherapee(http://rawtherapee.com) to align photo perspective,
first click the "Rotate right" button (turn entire image 90 degrees clockwise)
in the top panel; then click the "Transform" button in right panel, set "Lens/
Geometry" Method: Logarithmic, uncheck/disable "Auto-fill", set "Rotate" left
+0.20 (counterclockwise), set "Perspective" Method: Simple, Horizontal 0, and
Vertical -2.3; then click the "Save current image" icon or type [Ctrl+S]. The
saved png file (45.15 MB, 2896 x 3009 pixels) is nearly geometrically uniform;

Using freeware Gimp(https://www.gimp.org) for simple color correction, shadows
and highlights, and crop photo edges, could be done using RawTherapee, but the
Gimp program is easier to use and includes many unique image editing features.
With the file from RawTherapee opened in Gimp, in Colors "Shadows-Highlights",
try setting Shadows to a high number (+80) and Highlights to low number (-90);
click the "Crop Tool" icon [Shift+C] to clean up outside edges and remove the
excess triangular "wavy" portion cut-out from the ceiling; next, click "File",
"Export As..." png [Shift+Ctrl+E], set compression level 0 and click "Export";
this cropped file should be about 45.82 MB, 2859 x 2795 pixels, 236479 unique
colors. As is, this file is ideal for saving, sharing, viewing, printing, etc.

Using freeware Inkscape(https://inkscape.org) for adding layers of square and
radial grid lines, circles, ellipses, and color fills, open this file into the
first layer, click "Edit", "Resize page to selection"[Shift+Ctrl+R], lock this
layer, zoom to page [5], and save this file [Ctrl+S]; next, add a second layer,
click "Create rectangles and squares" [R], draw a small square anywhere on the
page while holding down the Control [Ctrl] key to maintain its 1:1 proportion;
in Path click "Path Effects", click "+" icon to "Add path effect", which opens
"Live Path Effects Selector"; click "Construct grid", set "Size X" 56 and "Size
Y" 56; zoom to selection [3] and resize this large square grid to approximately
the same size as the page; next, in Object click "Align and Distribute" [Shift+
Ctrl+A] and click the icons to center on both vertical axis and horizontal axis
"Relative to Page", zoom page [5], save [Ctrl+S]; in View click "Hide Dialogs"
[F12] and "Full Screen" [F11] to maximize work space, then zoom page width [6];
with grid selected, use "Up" arrow to incrementally move the grid up until its
horizontal centerline intersects the opposing knees of "Horus"-like figures at
the left and right side of the image; move grid's vertical centerline to bisect
opposing knees at the top, and the pointed "plumb bob" shape (as if to describe
the plumb-line), but opposing knees at the base are offset slightly to the left;
adjust grid size proportionally (holding down [Ctrl] key) until the seventeenth
(17th) line from the grid center is approximately tangent to the circle on all
four sides; for reference, the twenty-seventh (27th) line to the right of grid
center intersects the twenty-fifth (25th) line below grid center at the top of
the little black dot just above the far bottom-right corner of the image; also,
the fourteenth (14th) line to the right of grid center is tangent to the base
of the "decapitated" orb-shaped head which is separated from the body reposing
in the chair by the long black "crack" which runs the full length of the image;
in Object click "Fill and Stroke", set Stroke style "Width" 0.01 mm; zoom page
and save file; in Edit click "Duplicate", in Path click "Object to Path", then
in Object click "Objects to guide" (in View toggle "Guides" off/on [Shift+\]);

add another layer[Shift+Ctrl+N]; in View > "Show/Hide" > check/enable the "Tool
Controls Bar" and "Snap Controls Bar"; click the Arrow next to "Toggle snapping
on/off"[Shift+%] to open "popover" menu in "Advanced mode", check/enable "Guide
lines"; click "Create circles, ellipses and arcs"[E]; while holding down [Ctrl]
key, draw a circle starting at the "Handle to guide intersection" at the center
of the grid until the "Handle to Path" or "Handle to guide" 'x' appears at the
intersection of the nineteenth (19th, both vertical and horizontal) lines from
the grid center, maintaining thin (0.01 mm) stroke width; zoom to selection [3],
deselect [Esc], then draw a another circle starting at the center until the 'x'
appears at the first (1st) grid lines from grid center; select all [Ctrl+A], in
Path click "Object to Path" [Shift+Ctrl+C], in Extensions > Generate from path,
"Interpolate" Exponent 1.0, Interpolation steps 17, "Live preview" and in a few
moments, nineteen (19) concentric circles appear grouped together, click Apply,
close "Interpolate" window, in Edit click "Delete"[Delete] to remove the first
two (extra) inner and outer circles; lock layer, save, and close file [Ctrl+W]
to clear "undo history"; reopen this file, zoom to page and add a fourth layer;

click "Draw Bezier curves and straight lines" [B] icon on the toolbox and draw
a horizontal line from the center of grid to the outer edge on the right side,
in Edit click "Duplicate"[Ctrl+D], select all [Ctrl+A], in Object click "Align
and Distribute" [Shift+Ctrl+A], and Relative to "First selected", click "Align
right edges of objects to left edge of the anchor" to move copied line segment
to left side of grid center, in Object "Group" [Ctrl+G]; holding control[Ctrl]
key, select left line segment, in Object "Transform" [Shift+Ctrl+M], in "Move"
set Horizontal -1.000 mm, click Apply, select all, click "Align and Distribute"
[Shift+Ctrl+A], unlock grid layer, hold [Shift+Ctrl] and select grid, Relative
to "Last selected", click "Center on vertical axis", deselect all; select line
segment(group of 2), "Duplicate"[Ctrl+D], in Object "Rotate 90* CW", select all
[Ctrl+A], Group [Ctrl+G], Duplicate [Ctrl+D], Transform [Shift+Ctrl+M], Rotate
Angle +10.000*; again select all, group, duplicate, transform, rotate +20.000*;
select all, group, duplicate, transform, rotate +40.000*; finally, select all,
group, rotate +10.000*(note gaps for horizontal and vertical grid centerlines);
holding [Shift+Ctrl] to preserve aspect ratio, expand this radial grid so that
all lines extend just outside corners of image, set stroke width 0.01 mm; lock
all layers, save, close, backup; reopen file, zoom to page, add a fifth layer;

hide layers 1 , 2, and 4; unlock layer 3 (circles), select all, copy, deselect,
lock layer 3; in layer 5 click "Paste in Place"[Ctrl+Alt+V], ungroup, deselect,
and with guides enabled, select the smallest circle at center, hold the [Shift]
key and stretch the horizontal centerline selection handles one(1) guide square
outward, tangent to the next larger circle as indicated by the snap-enabled 'x'
and "cusp node to guide", resulting in a 2:1 integer-ratio ellipse; repeat this
step for each larger circle, 3:2, 4:3, 5:4, 6:5, 7:6, ... and so on until 19:18;
select all, set stroke width 0.01 mm; the largest circle (19) already exists in
layer 3, so delete it from layer 5; select all, copy, then add a sublayer under
current ellipse layer, paste in place, rotate 90* CW; lock and hide all layers;
save, close, reopen, zoom to page; show layers 1 (image) and 3 (circles); add a
sixth layer; starting at center draw a circle just large enough to circumscribe
entire image; set color fill to blue (hexadecimal RGBA #0000ffff), stroke width
zero(0), zoom to selection; in circle/arc toolbar set "Start" 355.000 and "End"
5.000, for a 10 degree circle sector centered on 0 polar degrees; in Path click
"Path Effects" [Ctrl+&], click "+" icon to "Add path effect", which opens "Live
Path Effects Selector"; click "Rotate copies", Number of copies 36, check Split
elements; press [Tab] key once to select next 10 degree sector counterclockwise
and set fill color to magenta (#ff00ffff); press tab, set fill to orange-yellow
(#ffbe00ff); tab, set fill to blue-violet (#4000ffff); tab, set red (#ff0000ff);
tab, yellow (#ffff00ff); tab, violet (#8000ffff); repeat tab or click to select
each next sector CCW, red-orange (#ff4001ff), green (#00ff00ff), violet-magenta
(#bf00feff), orange (#ff8000ff), cyan (#00ffffff), magenta (#ff00ffff), orange-
yellow, blue, red, yellow, blue-violet, red-orange, green, violet, orange, cyan,
violet-magenta, orange-yellow, blue, magenta, yellow, blue-violet, red, green,
violet, red-orange, cyan, violet-magenta, and finally, orange; save file, close,
backup, reopen, zoom to drawing, select first "Rotate copies" 10 degree segment
and change Starting angle from 0.00 to 5.00, rotating the entire group of solid
color segments five (5) degrees counterclockwise; select all, set fill "Opacity"
to (about) 7%, deselect, lock and show all layers, uncheck/disable guides, hide
dialogs, full screen, zoom page width; hold Shift and right mouse button to pan,
click + to zoom in, - to zoom out; save file, show dialogs, add a seventh layer;