Scaling Image Quality

[zeuspaul]

If I scale an image I know I will lose some quality.  Assume I scale an image to 3x.  I find that I over scaled it and then rescale to 2x the original size.  What does Gimp use for the basis of the intermediate scale?  Is it scaling down from the lossy 3x image?  Or does it have the original image in memory and thus scaling 2x from the original image resulting in a better quality scaled image?

[rich2005]

Logic says not the same. Gimp works with the result of the last transform, although you might not perceive any difference.

A small 400x400 pix test (A) I make and scale x2 (800 x 800) compared with (A) x3 then back down to 800 x 800 I can see no difference.

Not the same with larger scales and odd sizes. The (A) x 500% (2000 x 2000) then back to say 755 x 755 pix is not the same as (A) 200 x 200 -> 755 x 755

If you use the Unified Transform Tool, then the various transforms available scale / rotate / move ... are in memory until you commit the overall transform, then it is back to normal.