Quote:
	
	
		
			
				
					Originally Posted by  mldma
					 
				 
				Sorry,my poor english let you misunderstand the question: 
I want to change a scanned color Pdf to black and white Pdf (color fading into black and wihte)without change  the original margin,text size . can k2pdfopt do it? 
 thank you 
			
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 Try this:
k2pdfopt -mode copy -c- file.pdf
If you want the margins trimmed, add 
-t to the options.  The
 -c- turns off color output (makes it black and white).  You can adjust the grayscale some with the -g option, like Jens pointed out, and also with the contrast:  
-cmax option.