C: adding text to images

[Chris F.A. Johnson]

On Wed, 22 Dec 2010, Giles Orr wrote:

> A friend of mine recently sent me the following question.  I hadn't
> any idea, and got his approval to post here.  Can anyone assist?
>
> Question:
>
> Background: I'm looking at satellite data. I wrote a program in C that
> does the following: Slurp up raster data in HDF format, feed the data
> to a program that runs something called iterated conditional modes,
> then writes out the raster data in TIFF.
>
> Problem: How do I make a caption with a legend and some text in it?
> I really don't want to do this pixel-by-pixel in the raster data. I was
> hoping for an easy C function like:
>
> add_text (x_loc, y_loc, size, text_string);
>
> ....that would then make the caption in the TIFF.
>
> I have looked around, and will continue to do so, but haven't found
> anything I like yet. I know Gimp can do this, but I don't want to use
> the GUI: I'd like to use this in my C program.
>
> Any suggestions?

   Use ImageMagick. For example, this puts a white circle with a number
   in it:

  convert  -fill white -stroke black -draw "circle  30,30  17,17" \
          -font Helvetica-Bold -pointsize 18 -fill black \
          -draw 'text 20,37 "12"'  in.jpg out.jpg

-- 
    Chris F.A. Johnson, <http://cfajohnson.com>
    Author:
    Pro Bash Programming: Scripting the GNU/Linux Shell (2009, Apress)
    Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
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