Embedding text in images

[lukaszmail]

Does anyone know of a way to programatically embed text in an image
like jpeg? Perhaps some template with text placeholders that could be
updated at runtime and re-saved as jpeg? The idea is to create coupon
graphic that can be printed as jpeg, but it must be updated with
proper amount at runtime.

Thanks

Lukasz

[Daniel Pitts]

I would suggest two things:

1. Keep the original template as a lossless file (PNG, with the right
settings is nice for this)

2. Keep the "templated" text out of the graphics file altogether, and
have a process that will take the input image, and text specifications,
and create an output image (jpg is fine for this, but PNG will usually
have higher quality)

[Beej Jorgensen]

Seconded, what Daniel said about keeping the text information separate
from the original image and keeping the original as a PNG.

The Cairo lib (there are many, but it's one that I know of) has support
for reading and writing PNG files and for drawing text on surfaces:

http://www.cairographics.org/

If you need JPEG output, the classic libjpeg is pretty straightforward.

-Beej

[Daniel Pitts]

ImageMagic is also a good command-line based tool which I believe can
read/write PNGs and JPGs, and compose images with other images and text.

I haven't used it for that purpose specifically, but I seem to recall
its support being good enough for the purpose the OP described.

[Gene]

On Nov 9, 6:37 pm, Daniel Pitts
<newsgroup.spamfil...@virtualinfinity.net> wrote:
> Beej Jorgensen wrote:

> its support being good enough for the purpose the OP described.- Hide quoted text -

Right. I had a need to attach a caption as graphic characters on some
standard-sized (410x307) JPEGs. Here's a Windows command script that
does a reasonable job:

@echo off
rem
rem Add a caption to a slideshow image of standard size.
rem

echo -------------------------------------------------------------
echo You need to install ImageMagik before this script will work.
echo A Windows Setup version is available at www.imagemagick.org .
echo Press Ctrl-C to quit if you need to install first. Otherwise,
echo -------------------------------------------------------------
pause

set savedpath=%path%
path c:\ImageMagick-6.3.7\bin;%path%

rem Deal with bad args.
if a%2==a goto usage
if not exist %1 goto usage

rem parse image width into %%w and height into %%x
for /f "tokens=3" %%a in ('identify %1') do (
for /f "tokens=1,2 delims=x" %%w in ("%%a") do (
if not %%w==410 (
echo
-------------------------------------------------------------
echo Image file %1 is %%w pixels wide and needs to be 410.
goto usage
)
if %%x lss 307 (
echo
-------------------------------------------------------------
echo Image file %1 is %%x pixels high and needs to be at least
307.
goto usage
)
)
)
convert -background white -fill black -font Arial-Bold-Italic -
pointsize 14 -size 410x -gravity center caption:%2 caption.gif
if errorlevel 1 goto convert_error
convert %1 -crop 410x307-0-0 cropped.jpg
if errorlevel 1 goto crop_error
montage -tile 1x2 -geometry +0+0 cropped.jpg caption.gif complete.jpg
if errorlevel 1 goto montage_error
copy complete.jpg %1
if errorlevel 1 goto copy_error
del caption.gif
del cropped.jpg
del complete.jpg
start %1
goto done

:usage
echo -------------------------------------------------------------
echo usage:
echo caption GraphicFileName "Caption text."
echo note:
echo Graphic must be 410 pixels wide and at least 307 high.
echo -------------------------------------------------------------
)
goto done

:convert_error
echo -------------------------------------------------------------
echo text conversion error
echo -------------------------------------------------------------
goto done

:crop_error
echo -------------------------------------------------------------
echo error cropping image
echo -------------------------------------------------------------
goto done

:montage_error
echo -------------------------------------------------------------
echo error joining caption to image
echo -------------------------------------------------------------
goto done

:copy_error
echo -------------------------------------------------------------
echo can't write final image %1 (see complete.jpg for result)
echo -------------------------------------------------------------
goto done

:done
path %savedpath%
set savedpath=

[georges]

On Windows, simply use Win32 api (6 lines of code) do draw text over Jpeg