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Figure.image: Add the parameter 'invert' for option -I #4089

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Figure.image: Add the parameter 'invert' for option -I #4089

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Figure.image: Add the alias 'invert' for option -I
seisman Sep 15, 2025
d10b5bd
Merge branch 'main' into image/invert
seisman Dec 12, 2025
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12 changes: 11 additions & 1 deletion pygmt/src/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,13 +14,14 @@

@fmt_docstring
@use_alias(D="position", G="bitcolor")
def image(
def image( # noqa: PLR0913
self,
imagefile: PathLike,
projection: str | None = None,
region: Sequence[float | str] | str | None = None,
box: Box | bool = False,
monochrome: bool = False,
invert: bool = False,
verbose: Literal["quiet", "error", "warning", "timing", "info", "compat", "debug"]
| bool = False,
panel: int | Sequence[int] | bool = False,
Expand Down Expand Up @@ -48,6 +49,7 @@ def image(

$aliases
- F = box
- I = invert
- J = projection
- M = monochrome
- R = region
Expand Down Expand Up @@ -85,6 +87,13 @@ def image(
monochrome
Convert color image to monochrome grayshades using the (television)
YIQ-transformation.
invert
Invert 1-bit image before plotting, i.e., black pixels (on) becomes white (off)
and vice versa. Ignored if used with color images.
Comment on lines +90 to +92
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@yvonnefroehlich yvonnefroehlich Sep 15, 2025 •
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Hm, just trying this and maybe I am missing something here. I thought the remote raster image "vader1.png" is such a 1-bit image (see the last example at https://docs.generic-mapping-tools.org/dev/image.html#examples), but using I=True does not flip the black and white pixels as expected:

import pygmt

fig = pygmt.Figure()
fig.basemap(region=[-5, 5] * 2, projection="X3c/1c", frame=0)

fig.image(imagefile="@vader1.png", position="jLM")
fig.image(imagefile="@vader1.png", position="jMC", bitcolor=["gray+f", "blue+b"])
fig.image(imagefile="@vader1.png", position="jRM", I=True)  # Does not do something
# fig.image(imagefile="@vader1.png", position="jRM", bitcolor=["black+f", "white+b"])

fig.show()
image_invert

Same for

gmt image @vader1.png -I -png image_I_gmt
image_I_gmt

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@seisman seisman Sep 15, 2025

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Hmm, it looks like an upstream bug.

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@yvonnefroehlich yvonnefroehlich Sep 15, 2025

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I tested it with the gmt dev version, and still no inverted colors. Thus, I wrote an issue report at GenericMappingTools/gmt#8795.

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@seisman seisman Dec 10, 2025 •
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The upstream bug has been fixed.

I've added a note in the docstrings.


**Note**: There was an upstream GMT bug, so this feature may not work correctly
for some 1-bit images for GMT<=6.6.0.
See `PR #8837 <https://github.com/GenericMappingTools/gmt/pull/8837>`__.
$verbose
$panel
$perspective
Expand All @@ -95,6 +104,7 @@ def image(
aliasdict = AliasSystem(
F=Alias(box, name="box"),
M=Alias(monochrome, name="monochrome"),
I=Alias(invert, name="invert"),
).add_common(
J=projection,
R=region,
Expand Down