Be aware that when converting grey level to alpha, black = clear and white =
opaque, which is the opposite of what I thought it would have been.
On Mon, May 5, 2008 at 11:21 PM, Anthony Thyssen <[EMAIL PROTECTED]>
wrote:
> | >Hello,
> | >
> | >I have gray images and I want to transform intervals
> | >of gray values to transparent with PerlMagick, lets say
> | >[rgb: 0 0 0 0 ... rgb: 45 45 45 0]. I have tried it with
> | >
> | >for ($j = 0; $j <= 45; $j++) {
> | > $rgb_gray = 'rgb:' . ' ' . $j . ' ' . $j . ' ' . $j . ' ' . '0';
> | > $image->Transparent(colors=>"$rgb_gray");
> | >};
> | >
> | >but it seems that only 0 0 0 0 will be transformed to
> | >transparent (even if I choose an interval where
> | >black is not included). How can this task be done?
> | >Thank you!
> |
> Fred Weinhaus on wrote...
> | I am not sure I understand what you are trying to do. But process
> | your grayscale image without transparency to the form you want, then
> | add that processed image to your original as the alpha channel.
> |
> | See copyopacity
> |
> | http://www.imagemagick.org/Usage/compose/#copyopacity
> |
>
> It may also be that you need to use rgba: rather than rgb:
>
> Sorry for the delay, I have been on vacation in china for 5 weeks.
>
> However if the image is already a greyscale image (not just data)
> then it is probably faster to do it within IM as Fred described.
>
> If you just have a pure text data file, then there are methods to
> convert it to a greyscale image using say a PbmPlus type of image file
> format. That format has a minimal text header followed by either binary
> or text numbers. The image can be bitmap, greyscale or RGB, though not
> RGBA. You say its grey scle, so a PGM image format may be best, then
> you can use Im to convert that into transparency masks.
>
>
> Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
>
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