Available in pre-release 3.7
You can use SumatraPDF from command-line to extract images embedded in a PDF file.
To extract all images: SumatraPDF extract input.pdf
It’ll save each image in a file with name image-<object-number>.png.
Image extension depends on the type of the file i.e. jpeg images will be saved as .jpg file.

To extract specific images #

You can extract only specific images. In a PDF file each image has an object number.
First, you need to find out object numbers of embedded images: SumatraPDF info -I input.pdf
The output looks like:
Images (9):
        1       (1189 0 R):     [ Flate ] 400x300 8bpc DevRGB (3 0 R)
        1       (1189 0 R):     [ Flate ] 400x300 8bpc DevRGB (6 0 R)
        1       (1189 0 R):     [ Flate ] 602x250 8bpc DevRGB (10 0 R)
        1       (1189 0 R):     [ Flate ] 278x288 8bpc DevRGB (15 0 R)
3, 6, 10 and 15 are object numbers.
To extract image 3 and 15: SumatraPDF extract input.pdf 3 15
Reference: