How to achieve consistency for product photos?

[denzjos]

A way to match photos is to choose a reference photo and change other photos using the black, grey and white color pickers from the 'Colour / Levels'. First pick a dark area with the black picker, the white with te white picker and then go around on the photo with the grey picker until you find a place to click where you are satisfied with the result. Example and information (gimp item)
https://photo.stackexchange.com/question...3185#13185