You can store a "thumbnail" version of the whole image (or an ROI) if you do not need the full solution. You can pass the size of the desired ROI (one number will result in a square image).
have_cs140_1 = checkDet(env, 'cs140_1')
if have_cs140_1:
cs140_1 = DetObject('cs140_1' ,env, int(run), name='Rowland')
cs140_1.addROI('ROI',ROIs[1])
shape=200 #shape=[100,200] is also possible
cs140_1.ROI.addRebin(shape)
dets.append(cs140_1)