8.2.7. Controling 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.

8.2.7.1. Retrieve the data: the localizer dataset with contrast maps

from nilearn import datasets

localizer_dataset = datasets.fetch_localizer_button_task(get_anats=True)
localizer_anat_filename = localizer_dataset.anats[0]
localizer_tmap_filename = localizer_dataset.tmaps[0]

8.2.7.2. Plotting with enhancement of background image with dim=-.5

from nilearn import plotting
plotting.plot_stat_map(localizer_tmap_filename,
                       bg_img=localizer_anat_filename,
                       cut_coords=(36, -27, 66),
                       threshold=3, title="dim=-.5",
                       dim=-.5)
../../_images/sphx_glr_plot_dim_plotting_001.png

8.2.7.3. Plotting with no change of contrast in background image with dim=0

plotting.plot_stat_map(localizer_tmap_filename,
                       bg_img=localizer_anat_filename,
                       cut_coords=(36, -27, 66),
                       threshold=3, title="dim=0",
                       dim=0)
../../_images/sphx_glr_plot_dim_plotting_002.png

8.2.7.4. Plotting with decrease of constrast in background image with dim=.5

plotting.plot_stat_map(localizer_tmap_filename,
                       bg_img=localizer_anat_filename,
                       cut_coords=(36, -27, 66),
                       threshold=3, title="dim=.5",
                       dim=.5)
../../_images/sphx_glr_plot_dim_plotting_003.png

8.2.7.5. Plotting with more decrease in constrast with dim=1

plotting.plot_stat_map(localizer_tmap_filename,
                       bg_img=localizer_anat_filename,
                       cut_coords=(36, -27, 66),
                       threshold=3, title="dim=1",
                       dim=1)

plotting.show()
../../_images/sphx_glr_plot_dim_plotting_004.png

Total running time of the script: ( 0 minutes 3.534 seconds)

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