feature request for image show

[YongcaiHuang]

What is your suggestion?

feature goal

to request the image show function, like matplotlib.pyplot.imshow

motivating

interaction is the advantages of altair. in image processing and even deep learning image cases, exploration of image is necessary. on the other hands, matplotlib requires more code and final effect is not that good.

expected behavior

below is the example

1. show the image pixel position and value
2. interaction with widget, like slider

import matplotlib.pyplot as plt
from matplotlib import widgets
from skimage import data, color

ast_rgb = data.astronaut()
ast_hsv = color.rgb2hsv(ast_rgb)
ast_hsv = (ast_hsv * 255).astype('uint8')

fig = plt.figure()
axs = fig.subplots(4, 1, gridspec_kw={'height_ratios': [5, 5, 1, 1]})
img_origin_ax: plt.Axes = axs[0]
img_one_channel_ax: plt.Axes = axs[1]
threshold_slider_ax: plt.Axes = axs[2]
channel_slider_ax: plt.Axes = axs[3]

ori_img = img_origin_ax.imshow(ast_rgb)
img = img_one_channel_ax.imshow(ast_hsv[..., 0], cmap='gray')
img_origin_ax.axis('off')
img_one_channel_ax.axis('off')
threshold_slider = widgets.Slider(threshold_slider_ax, 'Threshold', 0, 255, valinit=128, valstep=1)
channel_slider = widgets.Slider(channel_slider_ax, 'Channel', 0, 2, valinit=0, valstep=1)

def update(val):
    threshold = threshold_slider.val
    channel = int(channel_slider.val)
    img_one_channel_ax.imshow(ast_hsv[..., channel] > threshold, cmap='gray')
    fig.canvas.draw_idle()

threshold_slider.on_changed(update)
channel_slider.on_changed(update)

plt.show()

https://github.com/user-attachments/assets/8a6fd90b-b283-4674-b486-7a7ded8defc7

Have you considered any alternative solutions?

No response

[joelostblom]

Thank you for the feature suggestion. I agree that supporting images would be an important improvement, and it is something that needs to be added in VegaLite before it can be added in Altair. I will close this as a duplicate and refer to the following issue to join the discussion of the implementation of image support in Vega-Lite https://github.com/vega/vega-lite/issues/9389

You might also find the discussions in these issues interesting:

• https://github.com/vega/altair/issues/891
• https://github.com/vega/altair/issues/3077
• https://github.com/vega/vega/issues/1015