Note
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Controlling the contrast of the background when plotting¶
The dim argument controls the contrast of the background.
dim modifies the contrast of this image: dim=0 leaves the image unchanged, negative values of dim enhance it, and positive values decrease it (dim the background).
This dim argument may also be useful for the plot_roi function used to display ROIs on top of a background image.
Retrieve the data: the localizer dataset with contrast maps¶
from nilearn import datasets
localizer_dataset = datasets.fetch_localizer_button_task()
# Contrast map of motor task
localizer_tmap_filename = localizer_dataset.tmap
# Subject specific anatomical image
localizer_anat_filename = localizer_dataset.anat
[get_dataset_dir] Dataset created in
/home/runner/nilearn_data/brainomics_localizer
[fetch_single_file] Downloading data from https://osf.io/hwbm2/download ...
[fetch_single_file] ...done. (2 seconds, 0 min)
[fetch_single_file] Downloading data from
https://osf.io/download/5d27ddc91c5b4a001b9ef9d0/ ...
[fetch_single_file] ...done. (2 seconds, 0 min)
[fetch_single_file] Downloading data from
https://osf.io/download/5d27d29145253a001c3e284f/ ...
[fetch_single_file] ...done. (2 seconds, 0 min)
[fetch_single_file] Downloading data from
https://osf.io/download/5d275ede1c5b4a001aa00c26/ ...
[_chunk_report_] Downloaded 5660672 of 13951266 bytes (40.6%%, 1.5s
remaining)
[fetch_single_file] ...done. (3 seconds, 0 min)
[fetch_single_file] Downloading data from
https://osf.io/download/5d27037f45253a001c3d4563/ ...
[fetch_single_file] ...done. (1 seconds, 0 min)
[fetch_single_file] Downloading data from
https://osf.io/download/5d7b8948fcbf44001c44e695/ ...
[fetch_single_file] ...done. (1 seconds, 0 min)
Plotting with enhancement of background image with dim=-.5¶
from nilearn.plotting import plot_stat_map, show
cut_coords = (36, -27, 66)
plot_stat_map(
localizer_tmap_filename,
bg_img=localizer_anat_filename,
cut_coords=cut_coords,
threshold=3,
title="dim=-.5",
dim=-0.5,
)

<nilearn.plotting.displays._slicers.OrthoSlicer object at 0x7f7c38052e20>
Plotting with no change of contrast in background image with dim=0¶
plot_stat_map(
localizer_tmap_filename,
bg_img=localizer_anat_filename,
cut_coords=cut_coords,
threshold=3,
title="dim=0",
dim=0,
)

<nilearn.plotting.displays._slicers.OrthoSlicer object at 0x7f7c10ff42e0>
Plotting with decrease of contrast in background image with dim=.5¶
plot_stat_map(
localizer_tmap_filename,
bg_img=localizer_anat_filename,
cut_coords=cut_coords,
threshold=3,
title="dim=.5",
dim=0.5,
)

<nilearn.plotting.displays._slicers.OrthoSlicer object at 0x7f7c38f8a0a0>
Plotting with more decrease in contrast with dim=1¶
plot_stat_map(
localizer_tmap_filename,
bg_img=localizer_anat_filename,
cut_coords=cut_coords,
threshold=3,
title="dim=1",
dim=1,
)
show()

Total running time of the script: (0 minutes 18.978 seconds)
Estimated memory usage: 108 MB