David Reitter on wrote... | I'm trying to render text in an image that is to be output in an | indexed-color format (GIF, XPM) with a designated transparent color. | | Unfortunately, the text in the resulting image is absolutely | unreadable - it seems as if most of the text is converted to | transparent pixels. It works fine when I output to PNG instead, but I | ultimately need XPM. | | I'm using the following construction to add my text: | | montage -fill black -font "Helvetica" -size 9 -geometry +0+0 -label | "hello" -background transparent trans.gif test.gif | | I'm attaching the input file trans.gif and the result test.gif. The | same problem occurs if I add the text, save as PNG and then convert | it to GIF. I'm using ImageMagick 6.2.7 on OS X. | | I couldn't find anything about this in the doc or via sensible Google | searches... | You image was not attached. but looking at the command, you are using a very thin font "Helvetica" at a small size (12 point).
The "-size 9" setting will not be used. Now at a small size most of the text will be rendered mostly as semi-transparent pixels on a transparent background. The problem is nothing to do with using a indexed image format, but a format that uses a boolean or on/off transparency method. Eg no semi-transparent pixels are posible. As the GIF and XPM formats are of this type, resulting in any pixel which is semi-transparent becomming either opaque or transparent, depending on the version of IM you are using. PNG does not have that limitation, which is why it is a prefered image format for modern applications. Try this... convert test.png test_def.gif convert test.png -channel A -threshold 80% test_70.gif convert test.png -channel A -threshold 30% test_30.gif The first is what you were getting. The second (70% threshold) is makes a lot more of the semi-transparent pixels opaque, making the text readable. The thrid is the oppisite. only pixels which are at least 30% opaque are made opaque. This method will let you control the GIF thresholding level for semi-transparency, which you obviously need. For more info see IM Examples, GIF Boolean Transparency http://www.cit.gu.edu.au/~anthony/graphics/imagick6/formats/#trans What I would like to see is a new setting to control the boolean threshold level for GIF and XPM formats. This method should NOT be linked with -fuzz what has a very different function, though in is some versions of IM linked to this problem. Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]> ----------------------------------------------------------------------------- Glad to be of service! --- A Door - ``Hitchhikers Guide to the Galaxy'' ----------------------------------------------------------------------------- Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/ _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
