hello!

can you please help me with fast numpy transform.

i have qimage (argb32) converted to numpy, so it's now an array of shape (128,128,4).

and i want the fastest way to convert it to grayscale -

the formula is (pseudocode):

`lerp(PIX, dot(PIX, (0.299, 0.587, 0.114)), alpha)`

where PIX - is current pixel (image[[i][j][:-1]]) rgb,

alpha is for blending between gray and color.

i am new for numpy, as i see the examples maybe there is a one-stroke-solution for it, very fast..

thank you!