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

On Tue, 4 Jul 2023, Susmita/Rajib wrote:
>
> Thank you very much indeed.
>
> I am sorry. Perhaps knoppix only has imagemagick installed, not
> graphicsmagick. So I had to remove the string "gm" from your given
> command line.

:-(

Most distributions also offer GraphicsMagick (see 
https://repology.org/project/graphicsmagick/versions), but Knoppix is 
a is a bootable Live system on CD, DVD or USB flash drive (is not a 
"distribution"), so it seems unable to provide any package options.

From http://ftp.uni-kl.de/pub/linux/knoppix-dvd/dpkg-l-dvd-861.txt, I 
see that knoppix does have GraphicsMagick in it but it seems they 
somehow forgot to include the tiny 'gm' utility.

> Like you used the keyword blue, how could the colour, Dark Blue,
> identified by the following value, as mentioned earlier too:
> The identifier for Dark Blue:
> PMS: 3591 C
> Hex Color: #06038D;
> RGB: (3,37,126)
> CMYK: (100,87,0,25)
> be used instead?

You could use

   -fill '#06038D'

instead of

   -fill blue

The RGB syntax indicated by Cristy should work with GraphicsMagick as 
well.

GraphicsMagick has a standard definition for 'DarkBlue' but it seems 
slightly different than your definition.

> In the coming days, I would be able to learn about the options. What I
> wouldn't learn is why you used the code-line the way you did.

It is due to learning how things work.  There are often multiple ways 
to solve the same problem.  There are definitely multiple ways to 
accomplish this particular task.

Looking at the utility 'help' output and reading the documentation is 
a good start.

It does not look like Cristy's solution would produce the same result.

> Did you acquire this specialised knowhow learnt by experience? Or was
> it because of your position of privilege as a specialised programmer?

It is partially due to 30 years of experience with ImageMagick + 
GraphicsMagick (since 1992).  Not because of any privilege since the 
information has always been available to all.

> So could you please share the insights and the reasons for your
> writing the code-line the way you did please? Did you write this code
> consciously, or did the code just came to you?

It is based on imagining an order of operations (left to right) which 
would achieve your desired result.

>
> Particularly, you have used two -colorspace options. then colorize and
> adjoin. Why? The reason behind your using such options?

The '-colorspace gray' assures that the image is in grayscale.  Then 
the '-colorspace rgb' implies that the image will be treated as if it 
has red, green, and blue channels.

The GIF format supports multiple frames in one file.  The 'adjoin' 
option controls if multiple frames should be output to one file, or to 
multiple files.  The +adjoin option disables appending the output to 
one file and assures that the output is put into multiple files as you 
said you wanted.  The use of '+' is extremely old syntax that 
ImageMagick borrowed from even older software.  For example, in the 
Unix Bourne shell, '-' turns an option on, and '+' turns an option 
off.  It sounds strange but it is what a programmer (Stephen Bourne) 
decided to use sometime between 1976 and 1979.  And then some popular 
software called X11 decided to use it  as well.

There is a long history which inspired/directed the development of 
ImageMagick, but GraphicsMagick split from ImageMagick some 20 years 
ago already!

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