Legacy ImageMagick Discussions Archive

anthony wrote:The is another VP method that means 'surround the image with the background color'.

anthony wrote:I mentioned that as only black, white, gray, and transparent has specific VP methods, if you want another color, say "maroon", then you will need to use the background VP method, OR use transparent and 'flatten' the image onto a background.

anthony wrote: The VP method basically defined what IM thinks is surrounding the image proper. You could for example tell it to just surrend the image with an infinite tile of itself!

anthony wrote: I am not certian why you composited the original image over a transparent one, if only to set a transparent border. It will not be needed with the give VP method.
I suggest you do either one or the other, both is overkill.

anthony wrote: You should be able to just set the VP method an distort the original image directly.

anthony wrote: PS: if you set the 'false' flag to 'true' the returned image will be sized to 'bestfit' the distorted image, with appropriate virtual canvas offsets (if wanted).

I am working to improve the current fuzziness of the distorted image.

f3k wrote:

anthony wrote:The is another VP method that means 'surround the image with the background color'.

another vp method different from setImageVirtualPixelMethod()? any idea which one that could be?

f3k wrote:i'm confused. i DO want to apply transparent, and even if wouldn't, which method should i apply then? and could you explain the "use transparent and flatten" method? use transparent how? flatten how?

supposing that there are two vp methods (the one i am already using, setImageVirtualPixelMethod(), and the "background vp method"), which are you referring to?

f3k wrote:hello folks,

i'm trying to accomplish some perspective distortion, but it doesn't seem to work as i imagine, so i'll post here the example that is supposed to work. it can be reviewed at http://www.imagemagick.org/Usage/distorts/. i'll take the chessboard example. the source image is the following:

the command line transformation:

Code: Select all

  convert checks.png -matte -virtual-pixel transparent \
          -distort Perspective '0,0,0,0  0,90,0,90  90,0,90,25  90,90,90,65' \
          checks_pers.png

and the (theoretical) result:

now, using php and the Imagick extension, i suppose that transforms into the following code:

Code: Select all

<?php
$testImagick = new Imagick("checks.png");
$testImagick->setImageMatteColor(new ImagickPixel("transparent"));
$testImagick->setImageVirtualPixelMethod(Imagick::VIRTUALPIXELMETHOD_TRANSPARENT);
$testImagick->distortImage(Imagick::DISTORTION_PERSPECTIVE, array(0,0,0,0,  0,90,0,90,  90,0,90,25,  90,90,90,65), false);
$testImagick->writeImage("checks_distorted.png");
$testImagick->destroy();
?>

unfortunately, this brings me the following result:

<?php
$im = new Imagick();

$im->newPseudoImage(100, 100, "pattern:checkerboard");
$im->setImageFormat('png');
$im->setImageMatte(true);

echo imagick::VIRTUALPIXELMETHOD_TRANSPARENT;      // outputs 8
echo $im->getImageVirtualPixelMethod();  // sets the VP to what I want (8 in theory)
$im->setImageVirtualPixelMethod(imagick::VIRTUALPIXELMETHOD_TRANSPARENT);  // does not output 8.  instead, it outputs 0, or imagick::VIRTUALPIXELMETHOD_UNDEFINED, which I assume points to the default imagick::VIRTUALPIXELMETHOD_EDGE
?>