Convert JPG images to Group4 Tiff Images (Preferably with ImageMagick)

I have a few thousand JPG images which are photographs of old documents in courthouse books (JPG was not my choice). I need to convert the images to black and white Group4 tif images. The images were not shot well. The pages have curves in them. Although the images look great as JPG, converting to Tiff Group4 is a challenge. Portions of the image are too light, while others are too dark. I can increase or decrease the brightness of an image but it affects the entire document making the light areas too light or the dark areas too dark. I'm hoping there is some sort of intelligent option that can convert these images. If Group 4 turns out to be impossible we may be able to accept LZW images if their size is under 2mb. I can't get the LZW size under 5mb to even test. I would prefer a solution using the Windows command line version of ImageMagick. It seems to be the most powerful image converter, but I do not understand all of the options. If you have an alternative magical solution I would love to hear about it. I would like to have a solution to convert the images myself rather than ship them off. I have attached a few JPG images along with my best efforts at a tiff conversion.