Image background correction for static object imaged using different background

Dear all,

Please I need help on background correction. I imaged a stationary object (person lying on a table) but with three different background scenes. The object position varies on each of the images despite the object was not moved (See image attached). The mean pixel value in the ROI (red rectangle) is 872mm, 843mm and 786mm for image a, b and c respectively.

Please is there any way I can correct the background so that the ROI value on all the images will be appproximately the same?.

Many thanks in anticipation of your help.

[Image Analyst]

Possibly. Upload the original image and original background image, not a screenshot of 3 pseudocolored images.