The .NET standard GDI+ library is the core of RadImageEditor and the and image scaling algorithm, which is used during the resizing is called Bicubic Interpolation. Unfortunately there is no known way to resize an image without distorting its quality at all, but currently the Bicubic Interpolation is preserving the image's information in the best possible way. This is why the image could be with different size after the interpolation, depending on its quality before the resizing.
Additionally, if you want to use another image scaling algorithm, you could implement a CustomGraphicsCore which inherits IGraphicsCore and to apply the desired interpolation in it.
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