Bug summary

Hi,
Whereasalpha = constant works with RGB image, this is not the case when working with anarray-type for alpha.
(In my real case, I can only pass standard imshow parameters likealphato the function of the library I use, and not a RGBA array).
Patrick

Code for reproduction

importnumpyasnpimportmatplotlib.pyplotaspltfromskimage.colorimportgray2rgbarr=np.random.random((10,10))arr_rgb=gray2rgb(arr)alpha=np.ones_like(arr)alpha[:5]=0.2plt.figure()plt.tight_layout()plt.subplot(121)plt.title("Expected outcome")plt.imshow(arr,alpha=alpha,cmap='gray')plt.subplot(122)plt.title("Actual outcome")plt.imshow(arr_rgb,alpha=alpha)plt.show()

Actual outcome

Expected outcome

Additional information

No response

Operating system

Windows

Matplotlib Version

3.7.1

Matplotlib Backend

TkAgg

Python version

Python 3.10.11

Jupyter version

No response

Installation

pip