How can we pass gpuArray in Cdata of imshow?

finalImage = imshow(gpuArray(imread(imName)));  % this is OK
BUT

set(finalImage,'CData',gpuArray(imread(imName))) ; % Is showing error

Error using matlab.graphics.primitive.Image/set

Error setting property 'CData' of class 'Image':
Value must be either:

Truecolor - a 4xN array of type numeric or logical type

Colormapped - an MxN vector of numeric or logical type

I am using this set CData in a while loop to save time.

Answer 1

[Rik]

Because image is not holding your hand (and imshow is), you need to do the work yourself. In this case that means you need to get the data from the gpuArray back out to a normal array with the gather function. I'm not sure if this will get you any speed increase compared to skipping the call to gpuArray in the first place.

[Tomycj]

So while creating and image object, the input array is automatically gathered, but not when you want to manually change its value? Is that what is happening here below?

M1 = gpuArray([1 2 3])
im=image('CData', M1,'CDataMapping','direct');  % This works
im.CData = M1                                   % This doesn't
im.Cdata = gather(M1)                           % This works, but is VERY slow