I run the code

pixels _ newImage form bits.
oldBits _ oldForm bits.
largeness _ oldBits size.
d _ oldForm depth.
1 to: largeness do:[:c| i _ oldBits at: c.
     oldpixel _ Color colorFromPixelValue: i depth: d.
     pixels at: c put: (oldpixel pixelValueForDepth: d)]

It works as expected in 32 bits depth but in 16 or 8
bits I get vertical stripes of transparency...

Anybody know why ?

Karl