To check whether the PDF is colored or BW, you can use Ghostscript (free, open-source, cross-platform):
Example commandline:
gs -o - -sDEVICE=inkcov /path/to/your.pdf
Example output:
Page 1
0.00000 0.00000 0.00000 0.02230 CMYK OK
Page 2
0.02360 0.02360 0.02360 0.02360 CMYK OK
Page 3
0.02525 0.02525 0.02525 0.00000 CMYK OK
Page 4
0.00000 0.00000 0.00000 0.01982 CMYK OK
You can see here that the page 4 is using no color, while pages 1+2+3
do. This case is particularly 'nasty' for people who want to save on
color ink: because all the C, M, Y (and K) values are exactly the same
for each of the pages 1-3, they possibly could appear to the human eye
not as color pages, but as ("rich") grayscale anyway (if each single
pixel is mixed with these color values).
Other ideas: How do I know if PDF pages are color or black-and-white?
To convert a PDF to TIFF, you can use GhostScript (free, open-source, cross-platform):
on Windows:
gswin32c -dNOPAUSE -q -g300x300 -sDEVICE=tiffg4 -dBATCH
-sOutputFile=output_file_name.tif input_file_name.pdf
on *nix:
gs -dNOPAUSE -q -g300x300 -sDEVICE=tiffg4 -dBATCH
-sOutputFile=output_file_name.tif input_file_name.pdf
Other ideas: Best way to convert pdf files to tiff files
To convert a PDF to PNG, you can use ImageMagick (free, open-source, cross-platform):
convert foo.pdf pages-%03d.png