A chapter has a full-page image at the end, and its last paragraph overflows two lines to a new page. How to make the last line stays in the bottom of a page so that there's no almost blank page before the image? Shrinking just a page is fine, but I think shrinking the whole chapter will leave no trace.
Let's say the two orphan lines are in page 2, and the image is in page 3, and I want the orphan lines is in page 1, and only the image is in page 2. Putting \pagebreak or \clubpenalty=10000 on the last line doesn't work. There's no paragraph with short last line to use \looseness=-1. Using \enlargethispage{2\baselineskip} the orphan lines and the image are both in page 2. The image then overflows the bottom margin of page 2.

\looseness=-1so it takes one less line? – David Carlisle Dec 13 '17 at 19:04\enlargethispage{2\baselineskip} doesn't really shrink the text, just makes the image not flush to the next page. I'd like to have it on its own page alone.If you use that command on the page before you show, the two lines of text will stay on that page and the image will be on a page on its own, which is what you say you want to happen? – David Carlisle Dec 13 '17 at 19:07\setstretchreducing inter-paragraph spacing? And where would you put the commands you say in the last comment? – Ooker Dec 14 '17 at 01:49\enlargethispageas you have shown no code, but basically your text is two lines two long to fit in the pages so find two facing pages earlier and make them each one line longer with\enlargethispage{\baselineskip}then the final two lines that you show at the top of your image should end on the page earlier, leaving the image on its own. – David Carlisle Dec 14 '17 at 07:40