how can I adapt the distance on images with different size?

if we have an image with size (860x440) the distance measure is 47mm. What is the same distance if the size of image is changed to (140x110).

Answer 1

[Image Analyst]

Depends if the image was resized to have the same scene, or if you cropped out a portion of it.

If you cropped, the mm per pixel will be the same.

If you resized the whole image so that the scene is the same scene just in fewer pixels, then the mm per pixel will increase.

[Ahmed Zaafouri]

Thkx a lot, the image will be resized and not cropped

[Image Analyst]

If the "distance measure" is the horizontal distance across the whole image and it's 47 mm then your original calibration is

originalMmPerPixel = 47 / 440

once you resize it so that it's only 110 pixels across (instead of 440 across) then the new calibration will be

newMmPerPixel = 47 / 110