I would like to save plots as .png files at a certain dpi resolution, import into MS Word, then set the width of the image to the correct length according to the dpi setting. However, changing the dpi with Plots.jl in 3 tested backends also changes the font size (and other attributes).
If font sizes are in units of points, and a point is 0.3528 mm, then shouldn’t font size be constant regardless of dpi settings?
For example I have a function that takes the number of columns I want a figure to occupy and a fraction of the max size allowed in each dimension. It prints out dimensional info as a convenience:
using Plots
pyplot()
backend = "pyplot"
function fig_size_px(;n_columns=n_columns::Int, dpi::Int=300, w_frac::Float64=1.0, h_frac::Float64=1.0)
MM_PER_IN = 25.4
w_mm_max = 90 * n_columns
w_mm = w_mm_max * w_frac
w_in = w_mm/MM_PER_IN
w_px::Int = round(Int32,w_in * dpi)
h_mm_max = 170
h_mm = h_mm_max * h_frac
h_in = h_mm/MM_PER_IN
h_px::Int = round(Int32,h_in * dpi)
println("DPI set to $(dpi).\n
$(n_columns) column wide\n
Figure width: $(w_px) pixels ($(round(Int32,w_mm_max/MM_PER_IN * dpi)) max), $(w_mm) mm ($(w_mm_max) max), $(round(w_in,digits=3)) in. ($(round(w_mm_max/MM_PER_IN,digits=3)) max)\n
Figure height: $(h_px) pixels ($(round(h_mm_max/MM_PER_IN * dpi)) max), $(h_mm) mm ($(h_mm_max) max), $(round(h_in,digits=3)) in. ($(round(h_mm_max/MM_PER_IN,digits=3)) max)")
return w_px, h_px
end
x = (0.0:0.01:2π)
y = sin.(x)
default_font_size = 12
title_font_size = 16
font_family = "Helvetica"
n_cols = 1
dpi_setting = 300
w_px, h_px = fig_size_px(n_columns=n_cols, dpi=dpi_setting, w_frac=0.5, h_frac=0.25)
f1 = plot(size=(w_px, h_px),
xtickfont = font(default_font_size, font_family),
ytickfont = font(default_font_size, font_family),
xlabelfont = font(default_font_size, font_family),
ylabelfont = font(default_font_size, font_family),
titlefont = font(default_font_size, font_family),
legendfont = font(default_font_size, font_family),
xguidfontsize = default_font_size,
yguidefontsize = default_font_size,
margin=5mm,
dpi=dpi_setting)
plot!(f1[1], x, y,
xlabel="x",
ylabel="sin(x)",
title="y = sin(x)",
label="y = sin(x)")
savefig("test_$(dpi_setting)-dpi_$(backend).png")
dpi_setting = 600
w_px, h_px = fig_size_px(n_columns=n_cols, dpi=dpi_setting, w_frac=0.5, h_frac=0.25)
f2 = plot(size=(w_px, h_px),
xtickfont = font(default_font_size, font_family),
ytickfont = font(default_font_size, font_family),
xlabelfont = font(default_font_size, font_family),
ylabelfont = font(default_font_size, font_family),
titlefont = font(default_font_size, font_family),
legendfont = font(default_font_size, font_family),
xguidfontsize = default_font_size,
yguidefontsize = default_font_size,
margin=5mm,
dpi=dpi_setting)
plot!(f2[1], x, y,
xlabel="x",
ylabel="sin(x)",
title="y = sin(x)",
label="y = sin(x)")
savefig("test_$(dpi_setting)-dpi_$(backend).png")
Testing with pyplot(), gr(), and plotly() (html → png) gives this when importing into Word and scalling the width to 45 mm where the backend labels are typed in Word with the font and font size specified.
