I have a strange problem. In some of the PDF readers, the images are not visible. In others, the images are visible but font size of the text below the image for that page becomes really tiny.
Is it a problem with the images?
Interim answer: Maybe.
There are related questions that already have discussions and answers, e.g.
If these do not solve your problem then to help folk answer your question some more pieces of information are needed such as those asked for in comments on your original question plus at least a couple more:
As to the interim answer: you will have seen from the linked questions that an unexpected appearance can be caused by a viewer (but it is not usually wrong in every viewer at even the highest magnification and also wrong when printed) or by software that has created an image or embedded it into a file or post-processed the file so the problem could be with the images, but it could be something else or a combination of factors.