how to use Spacing correctly?

[lg2578]

I'm dealing with some png images, some with spacing=1.63 and others have a spacing=1.5.I want to unify spacing to 1.5.
my code :

load_png= T.LoadImage() 
img=load_png(path)  
spacing_png= T.Spacing(pixdim=[1.5,1.5])
img=spacing_png(img[0]) #nothing happend
img[0].shape
the image's shape is still 266,266 as inputed
if it's a nii.gz file ，the above code works,but can't change the first dim
load_png= T.LoadImage()

img=load_png(path2) 
spacing_png= T.Spacing(pixdim=(2,2,2,2,1,1,1,1))
img=spacing_png(img[0]) #nothing happend
img[0].shape
input shape is 360,310,144
output:(360, 156, 72),the first dim didn't change, the other dims are changed to 1/2,

[lg2578]

I've got it.

load_png=T.Compose([
    T.LoadImage(image_only=True),
    T.AddChannel()
]) 

img=load_png(path2) 

# img={'img':img,''}
spacing_png= T.Spacing(pixdim=(1.5,1.5,3))
affine=np.array([
    [1.63,0,0,0],
    [0,1.63,0,0],
    [0,0,3,0],
    [0,0,0,1]
])
img=spacing_png(data_array=img,affine=affine) #nothing happend
# img[0].shape
# img[2]

# resize=T.Resize(sp)
# resize()
img[0].shape