Is there a better trick than Irfanview to get Google Books chapters saved?

If a fat reference book is out of print, and you want just one chapter,
with diagrams (not just the text), how can we improve upon this
semi-automated process given Irfanview on a Windows computer?

1. Search terms get you a books.google.com URL to the desired book.
2. You set up the book view to scroll page by page in full pages.
3. Bring up Irfanview: Options Capture/Screenshot
4. Irfanview: Capture area 5) Custom rectangle/region capture
5. Click the top left & note the numbers in Irfanview (e.g., 640x228).
6. Click the bottom right & note the numbers in Irfanview (e.g., 575x853).
7. Go back to Irfanview: Options Capture/Screenshot
8. Irfanview: Capture area 7) Fixed screen rectangle
X-pos: 640 Y-pos: 228 Width: 575 Height: 853
9. Scroll to the desired chapter page & press F11 (to capture the area).
10. Press the next-page button & press F11 (repeat as needed).
11. If needed, save as PDF from Irfanview (using Thumbnail Batch Dialog).
12. If needed, OCR the PDF to text (using software unknown to me).

This procedure works so I just want to ask technical improvement questions.

a. Is there a better method to capture the area of the screen?
b. Is there a way to get *more* of the Google Book that the first time?

Is there a better Windows trick to get Google Books chapters saved?