It should be enough if ImageMagick are in DLL search path(s): http://msdn.microsoft.com/en-us/library/7d83bc18.aspx

I had Windows 7 x64 PATH setup as C:\ImageMagick\VisualMagick\bin, however php_imagick.dll would not be loaded at all. Finally, only after relocating all appropriate libraries and modules into PHP root directory, I got php_imagick.dll loaded and working fine with PHP. It sounds as if Windows 7 x64 or PHP are not able to resolve the PATH. Please see previous "bug" report here: https://bugs.php.net/bug.php?id=66347

Clarification: While using Command Line, Windows are able to find exe files in C:\ImageMagick\VisualMagick\bin. That excludes the possibility that Windows are not able to resolve PATH.

Were the exe files statically linked? Does the "bin" directory contain all libraries?

I do not think the exe were linked statically; I have used “Dynamic Multi-threaded DLL runtimes” option for build. All exe and library files are in the same “bin” directory.

Are you running your tests via Apache or IIS? Does the same problem happen with command-line PHP?

I just tested this locally by adding path to ImageMagick DLLs to PATH, rebooting, running command line PHP with the script provided in the earlier bug. Seems to work as expected.

Environment (1):
Apache/2.4.4 (Win64) mod_fcgid/2.3.7;
All libraries and modules in PHP root folder;
Test file (testIM.php) in htdocs folder;

testIM.php
<?php 
$im = new imagick( 'rose.jpg' ); 
$im->thumbnailImage( 200, 0); 
$im->writeImage( 'rose.gif' ); 
?>

Running testIM.php from web browser – NO ERRORS.
Command line: C:\Users\user>php E:\host\phpTest\phpinfo.php – NO ERRORS.
Command line: C:\Users\user>php E:\host\phpTest\testIM.php – ERRORs as follows:

C:\Users\aras>php E:\wwhost\phpTest\testIM.php
PHP Fatal error:  Uncaught exception 'ImagickException' with message 'unable to
open image `rose.jpg': No such file or directory @ error/blob.c/OpenBlob/2643' in E:\wwhost\phpTest\testIM.php:2
Stack trace:
#0 E:\wwhost\phpTest\testIM.php(2): Imagick->__construct('rose.jpg')
#1 {main}
  thrown in E:\wwhost\phpTest\testIM.php on line 2

Fatal error: Uncaught exception 'ImagickException' with message 'unable to open
image `rose.jpg': No such file or directory @ error/blob.c/OpenBlob/2643' in E:\wwhost\phpTest\testIM.php:2
Stack trace:
#0 E:\wwhost\phpTest\testIM.php(2): Imagick->__construct('rose.jpg')
#1 {main}
  thrown in E:\wwhost\phpTest\testIM.php on line 2

Environment (2):
Libraries and modules absent in PHP root folder.

Test from browser ERROR:
Fatal error: Class 'imagick' not found in E:\wwhost\phpTest\testIM.php on line 2

phpinfo() - no imagick is loaded.

Please note that under Apache CWD will be the server root, even for PHP. To solve it, you have to ensure all the required DLLs are on the path. As such, this is a pure configuration issue.