[SOLVED] Bad text watermarking with IM7

[kwash]

I've being using text watermark with IM for quite some time following the website example and it always worked very well. But recently IM7 changed the text watermarking behavior by creating a bad effect. Now it is producing a non desirable background in the watermark like this:



Commands used:

Code: Select all

magick -size 130x50 xc:grey10 -font Arial -pointsize 25 -gravity center \
          -draw "fill gray50  text 0,0  'watermark'" \
          tmpfile-fgnd.png
          
magick -size 130x50 xc:black -font Arial -pointsize 25 -gravity center \
        -draw "fill white  text  1,1  'watermark'  \
                           text  0,0  'watermark'  \
               fill black  text -1,-1 'watermark'" \
        -alpha Off tmpfile-mask.png
        
magick tmpfile-fgnd.png tmpfile-mask.png -compose copy-opacity -composite watermark.png

magick mogrify -trim +repage watermark.png

magick background.png watermark.png -compose dissolve -define compose:args=85% -gravity center -geometry +0+0 -composite background-watermarked.png

The result is the same when switching to a classic IM6-compatible command style:

Code: Select all

convert -size 130x50 xc:grey10 -font Arial -pointsize 25 -gravity center \
          -draw "fill gray50  text 0,0  'watermark'" \
          tmpfile-fgnd.png
          
convert -size 130x50 xc:black -font Arial -pointsize 25 -gravity center \
        -draw "fill white  text  1,1  'watermark'  \
                           text  0,0  'watermark'  \
               fill black  text -1,-1 'watermark'" \
        +matte tmpfile-mask.png
        
composite -compose CopyOpacity tmpfile-mask.png tmpfile-fgnd.png watermark.png

mogrify -trim +repage watermark.png

composite -dissolve 85% -gravity center -geometry +0+0 watermark.png background.png background-watermarked.png

This undesired result is due to the command:

Code: Select all

magick tmpfile-fgnd.png tmpfile-mask.png -compose copy-opacity -composite watermark.png

(or in classic IM6-compatible command style due to the command:)

Code: Select all

composite -compose CopyOpacity tmpfile-mask.png tmpfile-fgnd.png watermark.png

This is being caused by the following git commit: 6156c31f93eed74b7441d509d97ce257d231c02d.

After reverting this git commit the result comes back to the expected one, which should be:


Using imagemagick git master version in Arch Linux x86_64.
Any help or comments would be appreciated.
Thank you.

[fmw42]

Your commands work fine for me on my Mac OSX snow leopard


Version: ImageMagick 7.0.2-6 Q16 x86_64 2016-08-01 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2016 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC Modules OpenMP
Delegates (built-in): bzlib cairo fftw fontconfig freetype gslib jbig jng jp2 jpeg lcms lqr ltdl lzma openexr png ps rsvg tiff webp x xml zlib


I get the very same result as your last image.

Note that properly, you should add -alpha off before -compose copy_opacity. But it works fine for me even without it.

What is your IM version and platform and version of libpng?

[kwash]

Thank you fmw42 for the reply and support.

Adding '-alpha Off' before '-compose copy-opacity' fixed it.

It was working without it since a very, very long time. As the example in the website doesn't mention it (or the legacy '+matte' as in IM6) and the result suddenly changed after that commit, I thought it could be a bug. The website example uses '+matte' only in the initial 'convert' command. Maybe the example in the website should be updated?

I'm using IM7 Q32 HDRI version git master (currently at 7.0.2.8.r11135.gc1c7fb4) and libpng 1.6.23 in Arch Linux x86_64.

[fmw42]

matte is deprecated in IM 7 in favor of -alpha on/off. See http://imagemagick.org/script/porting.php#cli

see also http://www.imagemagick.org/Usage/compose/#copyopacity

[fmw42]

IM 7 is more strict in syntax than IM 6.

[kwash]

Yes, I know that 'matte' is deprecated. That's why I used '-alpha Off' in 'convert' command in IM7 syntax to replace '+matte'.

The website example is for IM6, so it uses '+matte'. But it doesn't use '+matte' (or '-alpha Off') before '-compose CopyOpacity' as you pointed, so I thought that maybe it should be updated.

Anyway, it's fixed for me. Thank you.

[fmw42]

That web site example has not been upgraded in a long while and is using the outdated composite command rather than the more flexible convert ... -composite.