Re: How to have monocrome "Dark Blue" rather than "Black" for the following operation?

On Mon, 3 Jul 2023, Susmita/Rajib wrote:

> [   ...   ]
> Your first challenge would be that the JPEG format does not support
> transparency.  GIF and PNG formats do.

Perhaps something like this will work well for you:

   gm convert -density 100 name.pdf -colorspace Gray -colorspace rgb  \
     -fill blue -colorize 0/0/100 -transparent white +adjoin name-%03d.gif

or perhaps:

   gm convert -density 100 name.pdf -colorspace Gray -colorspace rgb  \
     -fill blue -colorize 0/0/100 -fuzz 1% -transparent white +adjoin \
     name-%03d.gif

If you are looking for arithmetic perfection, then it could be useful 
to know that relative intensities of the red, green, and blue, which 
make up grey (luma) are not uniformly proportional at all.  This is 
the equation for Rec.709 RGB

   Luma = 0.2126*red + 0.7152*green + 0.0722*blue

This suggests that perhaps the optimum colorize proportion for blue is 
something other than 100% if you are intending that the relative 
intensity of the result in blue is the same as the original gray 
image.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt