在运行时调整图像大小时的质量问题

I have a image file on the disk and I am resizing the file and saving it back to disk as a new image file. For the sake of this question, I am not bringing them into memory in order to display them on the screen, only to resize them and resave them. This all works just fine. However, the scaled images have artifacts on them like shown here: I have a image file on the disk and I am resizi