05-28-2019, 07:49 AM
Somehow you have different aspect ratios. Remember Gimp uses pixels so:
original image 5944 / 3566 = 1.6668
scaled image 9803 / 5906 = 1.6598
For scaling even using cm as units I advise letting Gimp do the arithmetic. With the width and height linked together
Using Scale Image : Enter 50 in the Height box, Click in the Width box and the size in pixels is determined. 9844 x 5906 pix.
9844 - 9803 = 41 pix difference = 41 / 300 ppi = 0.1366 inch = 3.47 mm
original image 5944 / 3566 = 1.6668
scaled image 9803 / 5906 = 1.6598
For scaling even using cm as units I advise letting Gimp do the arithmetic. With the width and height linked together
Using Scale Image : Enter 50 in the Height box, Click in the Width box and the size in pixels is determined. 9844 x 5906 pix.
9844 - 9803 = 41 pix difference = 41 / 300 ppi = 0.1366 inch = 3.47 mm