Meaning of 'dating the images' and 'over time'

[floratang]

VOA report
…………
Professional examinations are also important. See a doctor if a mole bleeds or itches or is bigger than six millimeters.

Knowing what your skin looks like will help you recognize any changes in the size, shape or color of growths. The Cleveland Clinic suggests taking pictures of moles and dating the images to compare over time. …………

Please tell me the meaning of "dating the images" and "over time". thanks!
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[all potted out]

To date the images means to record / mark the images with a date. For example, the image looks big on Monday and small on Tuesday...
Over time means for a period of time.
So you record the images for a period of time to see how they change during this time period.

[Pamela]

Hi floratang
As all potted out indicated dating the images means to put a date on the pictures of moles in order to compare them (with other moles, possibly) after an uncertain period of time. Possibly it's done to see the eventual changes or mutation of the moles over time.