Thanks @Tex2002ans for very detail answer
@Nate the great thanks to you2

I gess it would be best to use some 9.7" tablet (ipad or some android device)
Some of pictures are a4 paper format some are smaller. But the 90% are books dimension 16cm x 24cm.
These are books for the building profession. The professor advised to make maximum use today's technology. Earlier, it was difficult, actually not possible, to pull all the books on the construction site. You always need a little of something to be reminded. So I thought to process books for kindle. Given that this is too complicated, it is better to keep them in pdf format on the tablet. It is better to drag tablet than suitcase with 20 books.
It is to bad that kindle or kobo aren't so powerful. In tablet, pdf, I can't hold word and see what it means (if i do not understand it). That was the second reason for me to place books on my kindle paperwhite..