pixel perfect squares

[Ofnuts]

(03-04-2024, 11:18 PM)gimpygirl Wrote: What does interpolation mean: what does it do?

It tells how scaled  pixels are computed. For instance, in your case, the pixel at (0,3) (ie, 4th pixel down from the top left corner) in the 133x133 result corresponds to the three pixels between (0,9) and (0,11) in the 133x399 image.

• With Interpolation: None it is the copy of the "nearest neighbor", which is the pixel the closest to the corresponding source (here,  (0,9), but if you were using a non-integer scale factor, this could fall "between" two pixels). 
  
• With Interpolation: Linear it would use a weighed average (a good deal of the closest pixel, and a bit of the 3 other surrounding pixels). 
  
• The other algorithms are refinements that reduce blur. Cubic used to be popular because it wasn't too CPU intensive, but modern algorithms  (LoHalo and NoHalo) are well within the reach of any semi-recent computer (<20 years old).
  

Here since you are doing something close to pixels art, None is the best method because all other methods will introduce new colors.